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A mobile phone, or cell phone,^[a] is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones (landline phones). This radio frequency link connects to the switching systems of a mobile phone operator, providing access to the public switched telephone network (PSTN). Modern mobile telephony relies on a cellular network architecture, which is why mobile phones are often referred to as ‘cell phones’ in North America.

Beyond traditional voice communication, digital mobile phones have evolved to support a wide range of additional services. These include text messaging, multimedia messaging, email, and internet access (via LTE, 5G NR or Wi-Fi), as well as short-range wireless technologies like Bluetooth, infrared, and ultra-wideband (UWB).

Mobile phones also support a variety of multimedia capabilities, such as digital photography, video recording, and gaming. In addition, they enable multimedia playback and streaming, including video content, as well as radio and television streaming. Furthermore, mobile phones offer satellite-based services, such as navigation and messaging, as well as business applications and payment solutions (via near-field communication (NFC)).

Mobile phones offering only basic features are often referred to as feature phones (slang: “dumbphones”), while those with advanced computing power are known as smartphones.^[1]

The first handheld mobile phone was demonstrated by Martin Cooper of Motorola in New York City on 3 April 1973, using a handset weighing c. 2 kilograms (4.4 lbs).^[2] In 1979, Nippon Telegraph and Telephone (NTT) launched the world’s first cellular network in Japan.^[3] In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1993 to 2024, worldwide mobile phone subscriptions grew to over 9.1 billion; enough to provide one for every person on Earth.^[4][5] In the first quarter of 2016, the top smartphone developers worldwide were Samsung, Apple and Huawei; smartphone sales represented 78 percent of total mobile phone sales.^[6] For feature phones as of 2016, the top-selling brands were Samsung, Nokia and Alcatel.^[7]

Mobile phones are considered an important human invention as they have been one of the most widely used and sold pieces of consumer technology.^[8] The growth in popularity has been rapid in some places, for example, in the UK, the total number of mobile phones overtook the number of houses in 1999.^[9] Today, mobile phones are globally ubiquitous,^[10] and in almost half the world’s countries, over 90% of the population owns at least one.^[11]

History

Main article: History of mobile phones

A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a “pocket-size folding telephone with a very thin carbon microphone”. Early predecessors of cellular phones included analog radio communications from ships and trains. The race to create truly portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced in successive “generations”, starting with the early zeroth-generation (0G) services, such as Bell System‘s Mobile Telephone Service and its successor, the Improved Mobile Telephone Service. These 0G systems were not cellular, supported a few simultaneous calls, and were very expensive.

The first handheld cellular mobile phone was demonstrated by John F. Mitchell^[12][13] and Martin Cooper of Motorola in 1973, using a handset weighing 2 kilograms (4.4 lb).^[2] The first commercial automated cellular network (1G) analog was launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway, and Sweden.^[14] Several other countries then followed in the early to mid-1980s. These first-generation (1G) systems could support far more simultaneous calls but still used analog cellular technology. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone.

In 1991, the second-generation (2G) digital cellular technology was launched in Finland by Radiolinja on the GSM standard. This sparked competition in the sector as the new operators challenged the incumbent 1G network operators. The GSM standard is a European initiative expressed at the CEPT (“Conférence Européenne des Postes et Telecommunications”, European Postal and Telecommunications conference). The Franco-German R&D cooperation demonstrated the technical feasibility, and in 1987, a Memorandum of Understanding was signed between 13 European countries that agreed to launch a commercial service by 1991. The first version of the GSM standard had 6,000 pages. The IEEE and RSE awarded Thomas Haug and Philippe Dupuis the 2018 James Clerk Maxwell medal for their contributions to the first digital mobile telephone standard.^[15] In 2018, the GSM was used by over 5 billion people in over 220 countries. The GSM (2G) has evolved into 3G, 4G and 5G. The standardization body for GSM started at the CEPT Working Group GSM (Group Special Mobile) in 1982 under the umbrella of CEPT. In 1988, ETSI was established, and all CEPT standardization activities were transferred to ETSI. Working Group GSM became Technical Committee GSM. In 1991, it became Technical Committee SMG (Special Mobile Group) when ETSI tasked the committee with UMTS (3G). In addition to transmitting voice over digital signals, the 2G network introduced data services for mobile, starting with SMS text messages, then expanding to Multimedia Messaging Service (MMS), and mobile internet with a theoretical maximum transfer speed of 384 kbit/s (48 kB/s).

In 2001, the third-generation (3G) was launched in Japan by NTT DoCoMo on the WCDMA standard.^[16] This was followed by 3.5G or 3G+ enhancements based on the high-speed packet access (HSPA) family, allowing UMTS networks to have higher data transfer speeds and capacity. 3G is able to provide mobile broadband access of several Mbit/s to smartphones and mobile modems in laptop computers. This ensures it can be applied to mobile Internet access, VoIP, video calls, and sending large e-mail messages, as well as watching videos, typically in standard-definition quality.

By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications, such as streaming media.^[17] Consequently, the industry began looking to data-optimized fourth-generation (4G) technologies, with the promise of speed improvements up to tenfold over existing 3G technologies. The first publicly available LTE service was launched in Scandinavia by TeliaSonera in 2009. In the 2010s, 4G technology has found diverse applications across various sectors, showcasing its versatility in delivering high-speed wireless communication, such as mobile broadband, the internet of things (IoT), fixed wireless access, and multimedia streaming (including music, video, radio, and television).

Deployment of fifth-generation (5G) cellular networks commenced worldwide in 2019. The term “5G” was originally used in research papers and projects to denote the next major phase in mobile telecommunication standards beyond the 4G/IMT-Advanced standards. The 3GPP defines 5G as any system that adheres to the 5G NR (5G New Radio) standard. 5G can be implemented in low-band, mid-band or high-band millimeter-wave, with download speeds that can achieve gigabit-per-second (Gbit/s) range, aiming for a network latency of 1 ms. This near-real-time responsiveness and improved overall data performance are crucial for applications like online gaming, augmented and virtual reality, autonomous vehicles, IoT, and critical communication services.

Types

Smartphone

Main article: Smartphone

Smartphones are defined by their advanced computing capabilities, which include internet connectivity and access to a wide range of applications. The International Telecommunication Union measures those with Internet connection, which it calls Active Mobile-Broadband subscriptions (which includes tablets, etc.). In developed countries, smartphones have largely replaced earlier mobile technologies, while in developing regions, they account for around 50% of all mobile phone usage.

Feature phone

Main article: Feature phone

Feature phone is a term typically used as a retronym to describe mobile phones which are limited in capabilities in contrast to a modern smartphone. Feature phones typically provide voice calling and text messaging functionality, in addition to basic multimedia and Internet capabilities, and other services offered by the user’s wireless service provider. A feature phone has additional functions over and above a basic mobile phone, which is only capable of voice calling and text messaging.^[19][20] Feature phones and basic mobile phones tend to use a proprietary, custom-designed software and user interface. By contrast, smartphones generally use a mobile operating system that often shares common traits across devices.

Infrastructure

Main articles: Cellular network and Wi-Fi

The critical advantage that modern cellular networks have over predecessor systems is the concept of frequency reuse allowing many simultaneous telephone conversations in a given service area. This allows efficient use of the limited radio spectrum allocated to mobile services, and lets thousands of subscribers converse at the same time within a given geographic area.

Former systems would cover a service area with one or two powerful base stations with a range of up to tens of kilometers’ (miles), using only a few sets of radio channels (frequencies). Once these few channels were in use by customers, no further customers could be served until another user vacated a channel. It would be impractical to give every customer a unique channel since there would not be enough bandwidth allocated to the mobile service. As well, technical limitations such as antenna efficiency and receiver design limit the range of frequencies a customer unit could use.

A cellular network mobile phone system gets its name from dividing the service area into many small cells, each with a base station with (for example) a useful range on the order of a kilometer (mile). These systems have dozens or hundreds of possible channels allocated to them. When a subscriber is using a given channel for a telephone connection, that frequency is unavailable for other customers in the local cell and in the adjacent cells. However, cells further away can re-use that channel without interference as the subscriber’s handset is too far away to be detected. The transmitter power of each base station is coordinated to efficiently service its own cell, but not to interfere with the cells further away.

Automation embedded in the customer’s handset and in the base stations control all phases of the call, from detecting the presence of a handset in a service area, temporary assignment of a channel to a handset making a call, interface with the land-line side of the network to connect to other subscribers, and collection of billing information for the service. The automation systems can control the “hand off” of a customer handset moving between one cell and another so that a call in progress continues without interruption, changing channels if required. In the earliest mobile phone systems by contrast, all control was done manually; the customer would search for an unoccupied channel and speak to a mobile operator to request connection of a call to a landline number or another mobile. At the termination of the call the mobile operator would manually record the billing information.

Mobile phones communicate with cell towers that are placed to give coverage across a telephone service area, which is divided up into ‘cells’. Each cell uses a different set of frequencies from neighboring cells, and will typically be covered by three towers placed at different locations. The cell towers are usually interconnected to each other and the phone network and the internet by wired connections. Due to bandwidth limitations each cell will have a maximum number of cell phones it can handle at once. The cells are therefore sized depending on the expected usage density, and may be much smaller in cities. In that case much lower transmitter powers are used to avoid broadcasting beyond the cell.

In order to handle the high traffic, multiple towers can be set up in the same area (using different frequencies). This can be done permanently or temporarily such as at special events or in disasters. Cell phone companies will bring a truck with equipment to host the abnormally high traffic.

Capacity was further increased when phone companies implemented digital networks. With digital, one frequency can host multiple simultaneous calls.

Additionally, short-range Wi-Fi infrastructure is often used by smartphones as much as possible as it offloads traffic from cell networks on to local area networks.

Hardware

Main article: Mobile phone features

The common components found on all mobile phones are:

• A central processing unit (CPU), the processor of phones. The CPU is a microprocessor fabricated on a metal–oxide–semiconductor (MOS) integrated circuit (IC) chip.
• A battery, providing the power source for the phone functions. A modern handset typically uses a lithium-ion battery (LIB), whereas older handsets used nickel–metal hydride (Ni–MH) batteries.
• An input mechanism to allow the user to interact with the phone. These are a keypad for feature phones, and touch screens for most smartphones (typically with capacitive sensing).
• A display which echoes the user’s typing, and displays text messages, contacts, and more. The display is typically either a liquid-crystal display (LCD) or organic light-emitting diode (OLED) display.
• Speakers for sound.
• Subscriber identity module (SIM) cards and removable user identity module (R-UIM) cards.
• A hardware notification LED on some phones

Low-end mobile phones are often referred to as feature phones and offer basic telephony. Handsets with more advanced computing ability through the use of native software applications are known as smartphones. The first GSM phones and many feature phones had NOR flash memory, from which processor instructions could be executed directly in an execute in place architecture and allowed for short boot times. With smartphones, NAND flash memory was adopted as it has larger storage capacities and lower costs, but causes longer boot times because instructions cannot be executed from it directly, and must be copied to RAM memory first before execution.^[21]

Central processing unit

Mobile phones have central processing units (CPUs), similar to those in computers, but optimised to operate in low power environments.

Mobile CPU performance depends not only on the clock rate (generally given in multiples of hertz)^[22] but also the memory hierarchy also greatly affects overall performance. Because of these problems, the performance of mobile phone CPUs is often more appropriately given by scores derived from various standardized tests to measure the real effective performance in commonly used applications.

Display

Main article: Display device

One of the main characteristics of phones is the screen. Depending on the device’s type and design, the screen fills most or nearly all of the space on a device’s front surface. Many smartphone displays have an aspect ratio of 16:9, but taller aspect ratios became more common in 2017.

Screen sizes are often measured in diagonal inches or millimeters; feature phones generally have screen sizes below 90 millimetres (3.5 in). Phones with screens larger than 130 millimetres (5.2 in) are often called “phablets.” Smartphones with screens over 115 millimetres (4.5 in) in size are commonly difficult to use with only a single hand, since most thumbs cannot reach the entire screen surface; they may need to be shifted around in the hand, held in one hand and manipulated by the other, or used in place with both hands. Due to design advances, some modern smartphones with large screen sizes and “edge-to-edge” designs have compact builds that improve their ergonomics, while the shift to taller aspect ratios have resulted in phones that have larger screen sizes whilst maintaining the ergonomics associated with smaller 16:9 displays.^[23][24][25]

Liquid-crystal displays are the most common; others are IPS, LED, OLED, and AMOLED displays. Some displays are integrated with pressure-sensitive digitizers, such as those developed by Wacom and Samsung,^[26] and Apple’s “3D Touch” system.

Sound

In sound, smartphones and feature phones vary little. Some audio-quality enhancing features, such as Voice over LTE and HD Voice, have appeared and are often available on newer smartphones. Sound quality can remain a problem due to the design of the phone, the quality of the cellular network and compression algorithms used in long-distance calls.^[27][28] Audio quality can be improved using a VoIP application over WiFi.^[29] Cellphones have small speakers so that the user can use a speakerphone feature and talk to a person on the phone without holding it to their ear. The small speakers can also be used to listen to digital audio files of music or speech or watch videos with an audio component, without holding the phone close to the ear.

Battery

The typical lifespan of a mobile phone battery is approximately two to three years, although this varies based on usage patterns, environmental conditions, and overall care. Most modern mobile phones use lithium-ion (Li-ion) batteries, which are designed to endure between 500 and 2,500 charge cycles. The exact number of cycles depends on factors such as charging habits, operating temperature, and battery management systems.^[30]

Li-ion batteries gradually degrade over time due to chemical aging, leading to reduced capacity and performance, often noticeable after one or two years of regular use. Unlike older battery types, such as nickel-metal hydride (Ni-MH), Li-ion batteries do not need to be fully discharged to maintain their longevity. In fact, they perform best when kept between 30% and 80% of their full charge.^[31] While practices such as avoiding excessive heat and minimizing overcharging can help preserve battery health, many modern devices include built-in safeguards.^[32] These safeguards, typically managed by the phone’s internal battery management system (BMS), prevent overcharging by cutting off power once the battery reaches full capacity. Additionally, most contemporary chargers and devices are designed to regulate charging to minimize stress on the battery. Therefore, while good charging habits can positively impact battery longevity, most users benefit from these integrated protections, making battery maintenance less of a concern in day-to-day use.^[33][34]

Future mobile phone batteries are expected to utilize advanced technologies such as silicon-carbon (Si/C) batteries and solid-state batteries, which promise to offer higher energy densities, longer lifespans, and improved safety compared to current lithium-ion batteries.^[35][36][37]

SIM card

Main articles: SIM card and Removable User Identity Module

Mobile phones require a small microchip called a Subscriber Identity Module or SIM card, in order to function. The SIM card is approximately the size of a small postage stamp and is usually placed underneath the battery in the rear of the unit. The SIM securely stores the service-subscriber key (IMSI) and the K_i used to identify and authenticate the user of the mobile phone. The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device, provided that this is not prevented by a SIM lock. The first SIM card was made in 1991 by Munich smart card maker Giesecke & Devrient for the Finnish wireless network operator Radiolinja.^{[citation needed]}

A hybrid mobile phone can hold up to four SIM cards, with a phone having a different device identifier for each SIM Card. SIM and R-UIM cards may be mixed together to allow both GSM and CDMA networks to be accessed. From 2010 onwards, such phones became popular in emerging markets,^[38] and this was attributed to the desire to obtain the lowest calling costs.

When the removal of a SIM card is detected by the operating system, it may deny further operation until a reboot.^[39]

Software

Software platforms

Main article: Mobile operating system

This section needs expansion. You can help by making an edit request. (October 2018)

Feature phones have basic software platforms. Smartphones have advanced software platforms. Android OS has been the best-selling OS worldwide on smartphones since 2011.

Mobile app

Main article: Mobile app

A mobile app is a computer program designed to run on a mobile device, such as a smartphone. The term “app” is a shortening of the term “software application”.Messaging

See also: SMS and MMS

A common data application on mobile phones is Short Message Service (SMS) text messaging. The first SMS message was sent from a computer to a mobile phone in 1992 in the UK while the first person-to-person SMS from phone to phone was sent in Finland in 1993. The first mobile news service, delivered via SMS, was launched in Finland in 2000,^[40] and subsequently many organizations provided “on-demand” and “instant” news services by SMS. Multimedia Messaging Service (MMS) was introduced in March 2002.^[41]

Application stores

Main article: List of mobile app distribution platforms

The introduction of Apple’s App Store for the iPhone and iPod Touch in July 2008 popularized manufacturer-hosted online distribution for third-party applications (software and computer programs) focused on a single platform. There are a huge variety of apps, including video games, music products and business tools. Up until that point, smartphone application distribution depended on third-party sources providing applications for multiple platforms, such as GetJar, Handango, Handmark, and PocketGear. Following the success of the App Store, other smartphone manufacturers launched application stores, such as Google’s Android Market (later renamed to the Google Play Store), RIM’s BlackBerry App World, or Android-related app stores like Aptoide, Cafe Bazaar, F-Droid, GetJar, and Opera Mobile Store. In February 2014, 93% of mobile developers were targeting smartphones first for mobile app development.^[42]

Sales

By manufacturer

See also: List of best-selling mobile phones and List of mobile phone brands by country

Rank	Manufacturer	Strategy Analytics report[43]
1	Samsung	21%
2	Apple	16%
3	Xiaomi	13%
4	Oppo	10%
5	Vivo	9%
	Others	31%
Note: Vendor shipments are branded shipments and exclude OEM sales for all vendors.

As of 2022, the top five manufacturers worldwide were Samsung (21%), Apple (16%), Xiaomi (13%), Oppo (10%), and Vivo (9%).^[43]History

From 1983 to 1998, Motorola was market leader in mobile phones. Nokia was the market leader in mobile phones from 1998 to 2012.^[44] In Q1 2012, Samsung surpassed Nokia, selling 93.5 million units as against Nokia’s 82.7 million units. Samsung has retained its top position since then.

Aside from Motorola, European brands such as Nokia, Siemens and Ericsson once held large sway over the global mobile phone market, and many new technologies were pioneered in Europe. By 2010, the influence of European companies had significantly decreased due to fierce competition from American and Asian companies, to where most technical innovation had shifted.^[45][46] Apple and Google, both of the United States, also came to dominate mobile phone software.^[45]

By mobile phone operator

Main article: Mobile phone operator

The world’s largest individual mobile operator by number of subscribers is China Mobile, which has over 902 million mobile phone subscribers as of June 2018.^[47] Over 50 mobile operators have over ten million subscribers each, and over 150 mobile operators had at least one million subscribers by the end of 2009.^[48] In 2014, there were more than seven billion mobile phone subscribers worldwide, a number that is expected to keep growing.

Use

See also: Smartphone § Use

Mobile phones are used for a variety of purposes, such as keeping in touch with family members, for conducting business, and in order to have access to a telephone in the event of an emergency. Some people carry more than one mobile phone for different purposes, such as for business and personal use. Multiple SIM cards may be used to take advantage of the benefits of different calling plans. For example, a particular plan might provide for cheaper local calls, long-distance calls, international calls, or roaming.

The mobile phone has been used in a variety of diverse contexts in society. For example:

• A study by Motorola found that one in ten mobile phone subscribers have a second phone that is often kept secret from other family members. These phones may be used to engage in such activities as extramarital affairs or clandestine business dealings.^[49]
• Some organizations assist victims of domestic violence by providing mobile phones for use in emergencies. These are often refurbished phones.^[50]
• The advent of widespread text-messaging has resulted in the cell phone novel, the first literary genre to emerge from the cellular age, via text messaging to a website that collects the novels as a whole.^[51]
• Mobile telephony also facilitates activism and citizen journalism.
• The United Nations reported that mobile phones have spread faster than any other form of technology and can improve the livelihood of the poorest people in developing countries, by providing access to information in places where landlines or the Internet are not available, especially in the least developed countries. Use of mobile phones also spawns a wealth of micro-enterprises, by providing such work as selling airtime on the streets and repairing or refurbishing handsets.^[52]
• In Mali and other African countries, people used to travel from village to village to let friends and relatives know about weddings, births, and other events. This can now be avoided in areas with mobile phone coverage, which are usually more extensive than areas with just land-line penetration.
• The TV industry has recently started using mobile phones to drive live TV viewing through mobile apps, advertising, social TV, and mobile TV.^[53] It is estimated that 86% of Americans use their mobile phone while watching TV.
• In some parts of the world, mobile phone sharing is common. Cell phone sharing is prevalent in urban India, as families and groups of friends often share one or more mobile phones among their members. There are obvious economic benefits, but often familial customs and traditional gender roles play a part.^[54] It is common for a village to have access to only one mobile phone, perhaps owned by a teacher or missionary, which is available to all members of the village for necessary calls.^[55]
• Smartphones also have the use for individuals who suffer from diabetes. There are apps for patients with diabetes to self monitor their blood sugar, and can sync with flash monitors. The apps have a feature to send automated feedback or possible warnings to other family members or healthcare providers in the case of an emergency.

Content distribution

In 1998, one of the first examples of distributing and selling media content through the mobile phone was the sale of ringtones by Radiolinja in Finland. Soon afterwards, other media content appeared, such as news, video games, jokes, horoscopes, TV content and advertising. Most early content for mobile phones tended to be copies of legacy media, such as banner advertisements or TV news highlight video clips. Recently, unique content for mobile phones has been emerging, from ringtones and ringback tones to mobisodes, video content that has been produced exclusively for mobile phones.^{[citation needed]}

Mobile banking and payment

Main articles: Mobile banking and Mobile payment

See also: Branchless banking and Contactless payment

In many countries, mobile phones are used to provide mobile banking services, which may include the ability to transfer cash payments by secure SMS text message. Kenya’s M-PESA mobile banking service, for example, allows customers of the mobile phone operator Safaricom to hold cash balances which are recorded on their SIM cards. Cash can be deposited or withdrawn from M-PESA accounts at Safaricom retail outlets located throughout the country and can be transferred electronically from person to person and used to pay bills to companies.

Branchless banking has also been successful in South Africa and the Philippines. A pilot project in Bali was launched in 2011 by the International Finance Corporation and an Indonesian bank, Bank Mandiri.^[56]

Mobile payments were first trialled in Finland in 1998 when two Coca-Cola vending machines in Espoo were enabled to work with SMS payments. Eventually, the idea spread and in 1999, the Philippines launched the country’s first commercial mobile payments systems with mobile operators Globe and Smart.^{[citation needed]}

Some mobile phones can make mobile payments via direct mobile billing schemes, or through contactless payments if the phone and the point of sale support near field communication (NFC).^[57] Enabling contactless payments through NFC-equipped mobile phones requires the co-operation of manufacturers, network operators, and retail merchants.^[58][59]

Mobile tracking

See also: Cellphone surveillance and Mobile phone tracking

Mobile phones are commonly used to collect location data. While the phone is turned on, the geographical location of a mobile phone can be determined easily (whether it is being used or not) using a technique known as multilateration to calculate the differences in time for a signal to travel from the mobile phone to each of several cell towers near the owner of the phone.^[60][61]

The movements of a mobile phone user can be tracked by their service provider and, if desired, by law enforcement agencies and their governments. Both the SIM card and the handset can be tracked.^[60]

China has proposed using this technology to track the commuting patterns of Beijing city residents.^[62] In the UK and US, law enforcement and intelligence services use mobile phones to perform surveillance operations.^[63]

Hackers have been able to track a phone’s location, read messages, and record calls, through obtaining a subscribers phone number.^[64]

Electronic waste regulation

See also: Mobile phone recycling

Studies have shown that around 40–50% of the environmental impact of mobile phones occurs during the manufacture of their printed wiring boards and integrated circuits.^[65]

The average user replaces their mobile phone every 11 to 18 months,^[66] and the discarded phones then contribute to electronic waste. Mobile phone manufacturers within Europe are subject to the WEEE directive, and Australia has introduced a mobile phone recycling scheme.^[67]

Apple Inc. had an advanced robotic disassembler and sorter called Liam specifically for recycling outdated or broken iPhones.^[68]

Theft

According to the Federal Communications Commission, one out of three robberies involve the theft of a cellular phone.^{[citation needed]} Police data in San Francisco show that half of all robberies in 2012 were thefts of cellular phones.^{[citation needed]} An online petition on Change.org, called Secure our Smartphones, urged smartphone manufacturers to install kill switches in their devices to make them unusable if stolen. The petition is part of a joint effort by New York Attorney General Eric Schneiderman and San Francisco District Attorney George Gascón and was directed to the CEOs of the major smartphone manufacturers and telecommunication carriers.^[69] On 10 June 2013, Apple announced that it would install a “kill switch” on its next iPhone operating system, due to debut in October 2013.^[70]

All mobile phones have a unique identifier called IMEI. Anyone can report their phone as lost or stolen with their Telecom Carrier, and the IMEI would be blacklisted with a central registry.^[71] Telecom carriers, depending upon local regulation can or must implement blocking of blacklisted phones in their network. There are, however, a number of ways to circumvent a blacklist. One method is to send the phone to a country where the telecom carriers are not required to implement the blacklisting and sell it there,^[72] another involves altering the phone’s IMEI number.^[73] Even so, mobile phones typically have less value on the second-hand market if the phones original IMEI is blacklisted.

Conflict minerals

Main article: Conflict minerals

Demand for metals used in mobile phones and other electronics fuelled the Second Congo War, which claimed almost 5.5 million lives.^[74] In a 2012 news story, The Guardian reported: “In unsafe mines deep underground in eastern Congo, children are working to extract minerals essential for the electronics industry. The profits from the minerals finance the bloodiest conflict since the second world war; the war has lasted nearly 20 years and has recently flared up again. For the last 15 years, the Democratic Republic of the Congo has been a major source of natural resources for the mobile phone industry.”^[75] The company Fairphone has worked to develop a mobile phone that does not contain conflict minerals.^{[citation needed]}

Kosher phones

Due to concerns by the Orthodox Jewish rabbinate in Britain that texting by youths could waste time and lead to “immodest” communication, the rabbinate recommended that phones with text-messaging capability not be used by children; to address this, they gave their official approval to a brand of “Kosher” phones with no texting capabilities. Although these phones are intended to prevent immodesty, some vendors report good sales to adults who prefer the simplicity of the devices; other Orthodox Jews question the need for them.^[76]

In Israel, similar phones to kosher phones with restricted features exist to observe the sabbath; under Orthodox Judaism, the use of any electrical device is generally prohibited during this time, other than to save lives, or reduce the risk of death or similar needs. Such phones are approved for use by essential workers, such as health, security, and public service workers.^[77]

Restrictions

Restrictions on the use of mobile phones are applied in a number of different contexts, often with the goal of health, safety, security or proper functioning of an establishment, or as a matter of etiquette. Such contexts include:

While driving

Main articles: Mobile phones and driving safety and Texting while driving

Mobile phone use while driving, including talking on the phone, texting, or operating other phone features, is common but controversial. It is widely considered dangerous due to distracted driving. Being distracted while operating a motor vehicle has been shown to increase the risk of accidents. In September 2010, the US National Highway Traffic Safety Administration (NHTSA) reported that 995 people were killed by drivers distracted by cell phones. In March 2011, a US insurance company, State Farm Insurance, announced the results of a study which showed 19% of drivers surveyed accessed the Internet on a smartphone while driving.^[78] Many jurisdictions prohibit the use of mobile phones while driving. In Egypt, Israel, Japan, Portugal, and Singapore, both handheld and hands-free use of a mobile phone (which uses a speakerphone) is banned. In other countries, including the UK and France and in many US states, only handheld phone use is banned while hands-free use is permitted.

A 2011 study reported that over 90% of college students surveyed text (initiate, reply or read) while driving.^[79] The scientific literature on the dangers of driving while sending a text message from a mobile phone, or texting while driving, is limited. A simulation study at the University of Utah found a sixfold increase in distraction-related accidents when texting.^[80]

Due to the increasing complexity of mobile phones, they are often more like mobile computers in their available uses. This has introduced additional difficulties for law enforcement officials when attempting to distinguish one usage from another in drivers using their devices. This is more apparent in countries which ban both handheld and hands-free usage, rather than those which ban handheld use only, as officials cannot easily tell which function of the mobile phone is being used simply by looking at the driver. This can lead to drivers being stopped for using their device illegally for a phone call when, in fact, they were using the device legally, for example, when using the phone’s incorporated controls for car stereo, GPS or satnav.

A 2010 study reviewed the incidence of mobile phone use while cycling and its effects on behaviour and safety.^[81] In 2013, a national survey in the US reported the number of drivers who reported using their cellphones to access the Internet while driving had risen to nearly one of four.^[82] A study conducted by the University of Vienna examined approaches for reducing inappropriate and problematic use of mobile phones, such as using mobile phones while driving.^[83]

Accidents involving a driver being distracted by talking on a mobile phone have begun to be prosecuted as negligence similar to speeding. In the United Kingdom, from 27 February 2007, motorists who are caught using a hand-held mobile phone while driving will have three penalty points added to their license in addition to the fine of £60.^[84] This increase was introduced to try to stem the increase in drivers ignoring the law.^[85] Japan prohibits all mobile phone use while driving, including use of hands-free devices. New Zealand has banned hand-held cell phone use since 1 November 2009. Many states in the United States have banned texting on cell phones while driving. Illinois became the 17th American state to enforce this law.^[86] As of July 2010, 30 states had banned texting while driving, with Kentucky becoming the most recent addition on 15 July.^[87]

Public Health Law Research maintains a list of distracted driving laws in the United States. This database of laws provides a comprehensive view of the provisions of laws that restrict the use of mobile communication devices while driving for all 50 states and the District of Columbia between 1992 when first law was passed, through 1 December 2010. The dataset contains information on 22 dichotomous, continuous or categorical variables including, for example, activities regulated (e.g., texting versus talking, hands-free versus handheld), targeted populations, and exemptions.^[88]

On aircraft

This section is an excerpt from Mobile phones on aircraft.[edit]

In the U.S., Federal Communications Commission (FCC) regulations prohibit the use of mobile phones aboard aircraft in flight.^[89] Contrary to popular misconception, the Federal Aviation Administration (FAA) does not actually prohibit the use of personal electronic devices (including cell phones) on aircraft. Paragraph (b)(5) of 14 CFR 91.21 permits airlines to determine if devices can be used in flight, allowing use of “any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.”^[90]

In Europe, regulations and technology have allowed the limited introduction of the use of passenger mobile phones on some commercial flights, and elsewhere in the world many airlines are moving towards allowing mobile phone use in flight.^[91] Many airlines still do not allow the use of mobile phones on aircraft.^[92] Those that do often ban the use of mobile phones during take-off and landing.Many passengers are pressing airlines and their governments to allow and deregulate mobile phone use, while some airlines, under the pressure of competition, are also pushing for deregulation or seeking new technology which could solve the present problems.^[93] Official aviation agencies and safety boards are resisting any relaxation of the present safety rules unless and until it can be conclusively shown that it would be safe to do so. There are both technical and social factors which make the issues more complex than a simple discussion of safety versus hazard.^[94]

See also: Airplane mode

While walking

Main article: Smartphones and pedestrian safety

In 2010, an estimated 1500 pedestrians were injured in the US while using a cellphone and some jurisdictions have attempted to ban pedestrians from using their cellphones.^[95][96] Other countries, such as China and the Netherlands, have introduced special lanes for smartphone users to help direct and manage them.^[97][98]

In prisons

This section is an excerpt from Mobile phones in prison.[edit]

In most jurisdictions, prison inmates are forbidden from possessing mobile phones due to their ability to communicate with the outside world and other security issues. Mobile phones are one of the most smuggled items into prisons. They provide inmates the ability to make and receive unauthorized phone calls, send email and text messages, use social media, and follow news pertaining to their case, among other forbidden uses.^[99][100]

In hospitals

As of 2007, some hospitals had banned mobile devices due to a common misconception that their use would create significant electromagnetic interference.^[101][102]

Health effects

Main article: Mobile phone radiation and health

See also: Nomophobia and Mobile phone overuse

Screen time, the amount of time using a device with a screen, has become an issue for mobile phones since the adaptation of smartphones.^[103] Research is being conducted to show the correlation between screen time and the mental and physical harm in child development.^[104] To prevent harm, some parents and even governments have placed restrictions on its usage.^[105][106]

There have been rumors that mobile phone use can cause cancer, but this is a myth.^[107][108]

While there are rumors of mobile phones causing cancer, there was a study conducted by International Agency for Research on Cancer (IARC) that stated the there could be an increase risk of brain tumors with the use of smartphones, this is not confirmed. They also stated that with the lack of data for the research and the usage periods of 15 years will warrant further research for smartphones and the cause of brain tumors.^[109]

Educational impact

See also: Mobile phone use in schools

A study by the London School of Economics found that banning mobile phones in schools could increase pupils’ academic performance, providing benefits equal to one extra week of schooling per year.^[110]

Culture and popularity

See also: SMS language and Xelibri

Mobile phones are considered an important human invention as it has been one of the most widely used and sold pieces of consumer technology.^[8][10] They have also become culturally symbolic. In Japanese mobile phone culture for example, mobile phones are often decorated with charms. They have also become fashion symbols at times.^[111] The Motorola Razr V3 and LG Chocolate are two examples of devices that were popular for being fashionable while not necessarily focusing on the original purpose of mobile phones, i.e. a device to provide mobile telephony.^[112]

Some have also suggested that mobile phones or smartphones are a status symbol.^[113] For example a research paper suggested that owning specifically an Apple iPhone was seen to be a status symbol.^[114]

Text messaging, which are performed on mobile phones, has also led to the creation of ‘SMS language‘. It also led to the growing popularity of emojis.

A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered or motor-assisted, pedal-driven, single-track vehicle, with two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist.

Bicycles were introduced in the 19th century in Europe. By the early 21st century there were more than 1 billion bicycles.^[1][2] There are many more bicycles than cars.^[3][4][5] Bicycles are the principal means of transport in many regions. They also provide a popular form of recreation, and have been adapted for use as children’s toys. Bicycles are used for fitness, military and police applications, courier services, bicycle racing, and artistic cycling.

The basic shape and configuration of a typical upright or “safety” bicycle, has changed little since the first chain-driven model was developed around 1885.^[6][7][8] However, many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for many types of cycling. In the 21st century, electric bicycles have become popular.

The bicycle’s invention has had an enormous effect on society, both in terms of culture and of advancing modern industrial methods. Several components that played a key role in the development of the automobile were initially invented for use in the bicycle, including ball bearings, pneumatic tires, chain-driven sprockets, and tension-spoked wheels.^[9]

Etymology

The word bicycle first appeared in English print in The Daily News in 1868, to describe “Bysicles and trysicles” on the “Champs Elysées and Bois de Boulogne”.^[10] The word was first used in 1847 in a French publication to describe an unidentified two-wheeled vehicle, possibly a carriage.^[10] The design of the bicycle was an advance on the velocipede, although the words were used with some degree of overlap for a time.^[10][11]

Other words for bicycle include “bike”,^[12] “pushbike”,^[13] “pedal cycle”,^[14] or “cycle”.^[15] In Unicode, the code point for “bicycle” is 0x1F6B2. The entity 🚲 in HTML produces 🚲.^[16]

Although bike and cycle are used interchangeably to refer mostly to two types of two-wheelers, the terms still vary across the world. In India, for example, a cycle^[17] refers only to a two-wheeler using pedal power whereas the term bike is used to describe a two-wheeler using internal combustion engine or electric motors as a source of motive power instead of motorcycle/motorbike.

History

Main article: History of the bicycle

The “dandy horse“,^[18] also called Draisienne or Laufmaschine (“running machine”), was the first human means of transport to use only two wheels in tandem and was invented by the German Baron Karl von Drais. It is regarded as the first bicycle and von Drais is seen as the “father of the bicycle”,^{[19][20][21][22]} but it did not have pedals.^{[23][24][25][26]} Von Drais introduced it to the public in Mannheim in 1817 and in Paris in 1818.^[27][28] Its rider sat astride a wooden frame supported by two in-line wheels and pushed the vehicle along with his or her feet while steering the front wheel.^[27]

The first mechanically propelled, two-wheeled vehicle may have been built by Kirkpatrick MacMillan, a Scottish blacksmith, in 1839, although the claim is often disputed.^[29] He is also associated with the first recorded instance of a cycling traffic offense, when a Glasgow newspaper in 1842 reported an accident in which an anonymous “gentleman from Dumfries-shire… bestride a velocipede… of ingenious design” knocked over a little girl in Glasgow and was fined five shillings (equivalent to £30 in 2023).^[30]

In the early 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a new direction by adding a mechanical crank drive with pedals on an enlarged front wheel (the velocipede). This was the first in mass production. Another French inventor named Douglas Grasso had a failed prototype of Pierre Lallement’s bicycle several years earlier. Several inventions followed using rear-wheel drive, the best known being the rod-driven velocipede by Scotsman Thomas McCall in 1869. In that same year, bicycle wheels with wire spokes were patented by Eugène Meyer of Paris.^[31] The French vélocipède, made of iron and wood, developed into the “penny-farthing” (historically known as an “ordinary bicycle”, a retronym, since there was then no other kind).^[32] It featured a tubular steel frame on which were mounted wire-spoked wheels with solid rubber tires. These bicycles were difficult to ride due to their high seat and poor weight distribution. In 1868 Rowley Turner, a sales agent of the Coventry Sewing Machine Company (which soon became the Coventry Machinists Company), brought a Michaux cycle to Coventry, England. His uncle, Josiah Turner, and business partner James Starley, used this as a basis for the ‘Coventry Model’ in what became Britain’s first cycle factory.^[33]

The dwarf ordinary addressed some of these faults by reducing the front wheel diameter and setting the seat further back. This, in turn, required gearing—effected in a variety of ways—to efficiently use pedal power. Having to both pedal and steer via the front wheel remained a problem. Englishman J.K. Starley (nephew of James Starley), J.H. Lawson, and Shergold solved this problem by introducing the chain drive (originated by the unsuccessful “bicyclette” of Englishman Henry Lawson),^[34] connecting the frame-mounted cranks to the rear wheel. These models were known as safety bicycles, dwarf safeties, or upright bicycles for their lower seat height and better weight distribution, although without pneumatic tires the ride of the smaller-wheeled bicycle would be much rougher than that of the larger-wheeled variety. Starley’s 1885 Rover, manufactured in Coventry^[35] is usually described as the first recognizably modern bicycle.^[36] Soon the seat tube was added which created the modern bike’s double-triangle diamond frame.

Further innovations increased comfort and ushered in a second bicycle craze, the 1890s Golden Age of Bicycles. In 1888, Scotsman John Boyd Dunlop introduced the first practical pneumatic tire, which soon became universal. Willie Hume demonstrated the supremacy of Dunlop’s tyres in 1889, winning the tyre’s first-ever races in Ireland and then England.^[37][38] Soon after, the rear freewheel was developed, enabling the rider to coast. This refinement led to the 1890s invention^[39] of coaster brakes. Dérailleur gears and hand-operated Bowden cable-pull brakes were also developed during these years, but were only slowly adopted by casual riders.

The Svea Velocipede with vertical pedal arrangement and locking hubs was introduced in 1892 by the Swedish engineers Fredrik Ljungström and Birger Ljungström. It attracted attention at the World Fair and was produced in a few thousand units.

In the 1870s many cycling clubs flourished. They were popular in a time when there were no cars on the market and the principal mode of transportation was horse-drawn vehicles, such the horse and buggy or the horsecar. Among the earliest clubs was The Bicycle Touring Club, which has operated since 1878. By the turn of the century, cycling clubs flourished on both sides of the Atlantic, and touring and racing became widely popular. The Raleigh Bicycle Company was founded in Nottingham, England in 1888. It became the biggest bicycle manufacturing company in the world, making over two million bikes per year.^[40]

Bicycles and horse buggies were the two mainstays of private transportation just prior to the automobile, and the grading of smooth roads in the late 19th century was stimulated by the widespread advertising, production, and use of these devices.^[8] More than 1 billion bicycles have been manufactured worldwide as of the early 21st century.^[1][2] Bicycles are the most common vehicle of any kind in the world, and the most numerous model of any kind of vehicle, whether human-powered or motor vehicle, is the Chinese Flying Pigeon, with numbers exceeding 500 million.^[1] The next most numerous vehicle, the Honda Super Cub motorcycle, has more than 100 million units made,^[41] while most produced car, the Toyota Corolla, has reached 44 million and counting.^{[3][4][5][42]}

• Women on bicycles on unpaved road, US, late 19th century
• A penny-farthing or ordinary bicycle photographed in the Škoda Auto museum in the Czech Republic
• The Svea Velocipede by Fredrik Ljungström and Birger Ljungström, exhibited at the Swedish National Museum of Science and Technology
• Bicycle in Plymouth, England, at the start of the 20th century
• Brazilian princes (from left) Antônio, Luís, and Pedro on a triple tandem bicycle during their exile, 1891
• Man with a bicycle in Glengarry County, Ontario between 1895 and 1910
• The first bicycle by Baron Karl von Drais
• Drawing from an 1896 newspaper of The London Hansom Cycle
• Wooden draisine (around 1820), the first two-wheeler and as such the archetype of the bicycle
• Michaux’s son on a velocipede 1868
• Cyclists’ Touring Club sign on display at the National Museum of Scotland
• John Boyd Dunlop on a bicycle c. 1915
• 1886 Rover safety bicycle at the British Motor Museum. The first modern bicycle, it featured a rear-wheel-drive, chain-driven cycle with two similar-sized wheels. Dunlop’s pneumatic tire was added to the bicycle in 1888.

Uses

Bicycles are used for transportation, bicycle commuting, and utility cycling.^[43] They are also used professionally by mail carriers, paramedics, police, messengers, and general delivery services. Military uses of bicycles include communications, reconnaissance, troop movement, supply of provisions, and patrol, such as in bicycle infantries.^[44]

They are also used for recreational purposes, including bicycle touring, mountain biking, physical fitness, and play. Bicycle sports include racing, BMX racing, track racing, criterium, roller racing, sportives and time trials. Major multi-stage professional events are the Giro d’Italia, the Tour de France, the Vuelta a España, the Tour de Pologne, and the Volta a Portugal. They are also used for entertainment and pleasure in other ways, such as in organised mass rides, artistic cycling and freestyle BMX.

Technical aspects

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The bicycle has undergone continual adaptation and improvement since its inception. These innovations have continued with the advent of modern materials and computer-aided design, allowing for a proliferation of specialized bicycle types, improved bicycle safety, and riding comfort.^[45]

Types

Main article: List of bicycle types

Bicycles can be categorized in many different ways: by function, by number of riders, by general construction, by gearing or by means of propulsion. The more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX bikes. Less common are tandems, low riders, tall bikes, fixed gear, folding models, amphibious bicycles, cargo bikes, recumbents and electric bicycles.

Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as “bikes” or “cycles”.

Dynamics

Main article: Bicycle and motorcycle dynamics

A bicycle stays upright while moving forward by being steered so as to keep its center of mass over the wheels.^[46] This steering is usually provided by the rider, but under certain conditions may be provided by the bicycle itself.^[47]

The combined center of mass of a bicycle and its rider must lean into a turn to successfully navigate it. This lean is induced by a method known as countersteering, which can be performed by the rider turning the handlebars directly with the hands^[48] or indirectly by leaning the bicycle.^[49]

Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel to flip longitudinally.^[50] The act of purposefully using this force to lift the rear wheel and balance on the front without tipping over is a trick known as a stoppie, endo, or front wheelie.

Performance

Main article: Bicycle performance

The bicycle is extraordinarily efficient in both biological and mechanical terms. The bicycle is the most efficient human-powered means of transportation in terms of energy a person must expend to travel a given distance.^[51] From a mechanical viewpoint, up to 99% of the energy delivered by the rider into the pedals is transmitted to the wheels, although the use of gearing mechanisms may reduce this by 10–15%.^[52][53] In terms of the ratio of cargo weight a bicycle can carry to total weight, it is also an efficient means of cargo transportation.

A human traveling on a bicycle at low to medium speeds of around 16–24 km/h (10–15 mph) uses only the power required to walk. Air drag, which is proportional to the square of speed, requires dramatically higher power outputs as speeds increase. If the rider is sitting upright, the rider’s body creates about 75% of the total drag of the bicycle/rider combination. Drag can be reduced by seating the rider in a more aerodynamically streamlined position. Drag can also be reduced by covering the bicycle with an aerodynamic fairing. The fastest recorded unpaced speed on a flat surface is 144.18 km/h (89.59 mph).^[54]

In addition, the carbon dioxide generated in the production and transportation of the food required by the bicyclist, per mile traveled, is less than ¹⁄₁₀ that generated by energy efficient motorcars.^[55]

• A recumbent bicycle
• Balance bicycle for young children

Parts

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Frame

Main article: Bicycle frame

The great majority of modern bicycles have a frame with upright seating that looks much like the first chain-driven bike.^[6][7][8] These upright bicycles almost always feature the diamond frame, a truss consisting of two triangles: the front triangle and the rear triangle. The front triangle consists of the head tube, top tube, down tube, and seat tube. The head tube contains the headset, the set of bearings that allows the fork to turn smoothly for steering and balance. The top tube connects the head tube to the seat tube at the top, and the down tube connects the head tube to the bottom bracket. The rear triangle consists of the seat tube and paired chain stays and seat stays. The chain stays run parallel to the chain, connecting the bottom bracket to the rear dropout, where the axle for the rear wheel is held. The seat stays connect the top of the seat tube (at or near the same point as the top tube) to the rear fork ends.

Historically, women’s bicycle frames had a top tube that connected in the middle of the seat tube instead of the top, resulting in a lower standover height at the expense of compromised structural integrity, since this places a strong bending load in the seat tube, and bicycle frame members are typically weak in bending. This design, referred to as a step-through frame or as an open frame, allows the rider to mount and dismount in a dignified way while wearing a skirt or dress. While some women’s bicycles continue to use this frame style, there is also a variation, the mixte, which splits the top tube laterally into two thinner top tubes that bypass the seat tube on each side and connect to the rear fork ends. The ease of stepping through is also appreciated by those with limited flexibility or other joint problems. Because of its persistent image as a “women’s” bicycle, step-through frames are not common for larger frames.

Step-throughs were popular partly for practical reasons and partly for social mores of the day. For most of the history of bicycles’ popularity women have worn long skirts, and the lower frame accommodated these better than the top-tube. Furthermore, it was considered “unladylike” for women to open their legs to mount and dismount—in more conservative times women who rode bicycles at all were vilified as immoral or immodest. These practices were akin to the older practice of riding horse sidesaddle.^[56]

Another style is the recumbent bicycle. These are inherently more aerodynamic than upright versions, as the rider may lean back onto a support and operate pedals that are on about the same level as the seat. The world’s fastest bicycle is a recumbent bicycle but this type was banned from competition in 1934 by the Union Cycliste Internationale.^[57]

Historically, materials used in bicycles have followed a similar pattern as in aircraft, the goal being high strength and low weight. Since the late 1930s alloy steels have been used for frame and fork tubes in higher quality machines. By the 1980s aluminum welding techniques had improved to the point that aluminum tube could safely be used in place of steel. Since then aluminum alloy frames and other components have become popular due to their light weight, and most mid-range bikes are now principally aluminum alloy of some kind.^[where?] More expensive bikes use carbon fibre due to its significantly lighter weight and profiling ability, allowing designers to make a bike both stiff and compliant by manipulating the lay-up. Virtually all professional racing bicycles now use carbon fibre frames, as they have the best strength to weight ratio. A typical modern carbon fiber frame can weigh less than 1 kilogram (2.2 lb).

Other exotic frame materials include titanium and advanced alloys. Bamboo, a natural composite material with high strength-to-weight ratio and stiffness^[58] has been used for bicycles since 1894.^[59] Recent versions use bamboo for the primary frame with glued metal connections and parts, priced as exotic models.^[59][60][61]

• Diagram of a bicycle
• A Triumph with a step-through frame
• A carbon fiber Trek Y-Foil from the late 1990s

Drivetrain and gearing

Main article: Bicycle drivetrain systems

The drivetrain begins with pedals which rotate the cranks, which are held in axis by the bottom bracket. Most bicycles use a chain to transmit power to the rear wheel. A very small number of bicycles use a shaft drive to transmit power, or special belts. Hydraulic bicycle transmissions have been built, but they are currently inefficient and complex.

Since cyclists’ legs are most efficient over a narrow range of pedaling speeds, or cadence, a variable gear ratio helps a cyclist to maintain an optimum pedalling speed while covering varied terrain. Some, mainly utility, bicycles use hub gears with between 3 and 14 ratios, but most use the generally more efficient dérailleur system, by which the chain is moved between different cogs called chainrings and sprockets to select a ratio. A dérailleur system normally has two dérailleurs, or mechs, one at the front to select the chainring and another at the back to select the sprocket. Most bikes have two or three chainrings, and from 5 to 12 sprockets on the back, with the number of theoretical gears calculated by multiplying front by back. In reality, many gears overlap or require the chain to run diagonally, so the number of usable gears is fewer.

An alternative to chaindrive is to use a synchronous belt. These are toothed and work much the same as a chain—popular with commuters and long distance cyclists they require little maintenance. They cannot be shifted across a cassette of sprockets, and are used either as single speed or with a hub gear.

Different gears and ranges of gears are appropriate for different people and styles of cycling. Multi-speed bicycles allow gear selection to suit the circumstances: a cyclist could use a high gear when cycling downhill, a medium gear when cycling on a flat road, and a low gear when cycling uphill. In a lower gear every turn of the pedals leads to fewer rotations of the rear wheel. This allows the energy required to move the same distance to be distributed over more pedal turns, reducing fatigue when riding uphill, with a heavy load, or against strong winds. A higher gear allows a cyclist to make fewer pedal turns to maintain a given speed, but with more effort per turn of the pedals.

With a chain drive transmission, a chainring attached to a crank drives the chain, which in turn rotates the rear wheel via the rear sprocket(s) (cassette or freewheel). There are four gearing options: two-speed hub gear integrated with chain ring, up to 3 chain rings, up to 12 sprockets, hub gear built into rear wheel (3-speed to 14-speed). The most common options are either a rear hub or multiple chain rings combined with multiple sprockets (other combinations of options are possible but less common).

• A bicycle with shaft drive instead of a chain
• A set of rear sprockets (also known as a cassette) and a derailleur
• Hub gear

Steering

The handlebars connect to the stem that connects to the fork that connects to the front wheel, and the whole assembly connects to the bike and rotates about the steering axis via the headset bearings. Three styles of handlebar are common. Upright handlebars, the norm in Europe and elsewhere until the 1970s, curve gently back toward the rider, offering a natural grip and comfortable upright position. Drop handlebars “drop” as they curve forward and down, offering the cyclist best braking power from a more aerodynamic “crouched” position, as well as more upright positions in which the hands grip the brake lever mounts, the forward curves, or the upper flat sections for increasingly upright postures. Mountain bikes generally feature a ‘straight handlebar’ or ‘riser bar’ with varying degrees of sweep backward and centimeters rise upwards, as well as wider widths which can provide better handling due to increased leverage against the wheel.

Seating

Saddles also vary with rider preference, from the cushioned ones favored by short-distance riders to narrower saddles which allow more room for leg swings. Comfort depends on riding position. With comfort bikes and hybrids, cyclists sit high over the seat, their weight directed down onto the saddle, such that a wider and more cushioned saddle is preferable. For racing bikes where the rider is bent over, weight is more evenly distributed between the handlebars and saddle, the hips are flexed, and a narrower and harder saddle is more efficient. Differing saddle designs exist for male and female cyclists, accommodating the genders’ differing anatomies and sit bone width measurements, although bikes typically are sold with saddles most appropriate for men. Suspension seat posts and seat springs provide comfort by absorbing shock but can add to the overall weight of the bicycle.

A recumbent bicycle has a reclined chair-like seat that some riders find more comfortable than a saddle, especially riders who suffer from certain types of seat, back, neck, shoulder, or wrist pain. Recumbent bicycles may have either under-seat or over-seat steering.

Brakes

Main article: Bicycle brake

Bicycle brakes may be rim brakes, in which friction pads are compressed against the wheel rims; hub brakes, where the mechanism is contained within the wheel hub, or disc brakes, where pads act on a rotor attached to the hub. Most road bicycles use rim brakes, but some use disc brakes.^[63] Disc brakes are more common for mountain bikes, tandems and recumbent bicycles than on other types of bicycles, due to their increased power, coupled with an increased weight and complexity.^[64]

With hand-operated brakes, force is applied to brake levers mounted on the handlebars and transmitted via Bowden cables or hydraulic lines to the friction pads, which apply pressure to the braking surface, causing friction which slows the bicycle down. A rear hub brake may be either hand-operated or pedal-actuated, as in the back pedal coaster brakes which were popular in North America until the 1960s.

Track bicycles do not have brakes, because all riders ride in the same direction around a track which does not necessitate sharp deceleration. Track riders are still able to slow down because all track bicycles are fixed-gear, meaning that there is no freewheel. Without a freewheel, coasting is impossible, so when the rear wheel is moving, the cranks are moving. To slow down, the rider applies resistance to the pedals, acting as a braking system which can be as effective as a conventional rear wheel brake, but not as effective as a front wheel brake.^[65]

Suspension

Main article: Bicycle suspension

Bicycle suspension refers to the system or systems used to suspend the rider and all or part of the bicycle. This serves two purposes: to keep the wheels in continuous contact with the ground, improving control, and to isolate the rider and luggage from jarring due to rough surfaces, improving comfort.

Bicycle suspensions are used primarily on mountain bicycles, but are also common on hybrid bicycles, as they can help deal with problematic vibration from poor surfaces. Suspension is especially important on recumbent bicycles, since while an upright bicycle rider can stand on the pedals to achieve some of the benefits of suspension, a recumbent rider cannot.

Basic mountain bicycles and hybrids usually have front suspension only, whilst more sophisticated ones also have rear suspension. Road bicycles tend to have no suspension.

Wheels and tires

Main articles: Bicycle wheel and Bicycle tire

The wheel axle fits into fork ends in the frame and fork. A pair of wheels may be called a wheelset, especially in the context of ready-built “off the shelf”, performance-oriented wheels.

Tires vary enormously depending on their intended purpose. Road bicycles use tires 18 to 25 millimeters wide, most often completely smooth, or slick, and inflated to high pressure to roll fast on smooth surfaces. Off-road tires are usually between 38 and 64 mm (1.5 and 2.5 in) wide, and have treads for gripping in muddy conditions or metal studs for ice.

Groupset

Groupset generally refers to all of the components that make up a bicycle excluding the bicycle frame, fork, stem, wheels, tires, and rider contact points, such as the saddle and handlebars.

Accessories

Some components, which are often optional accessories on sports bicycles, are standard features on utility bicycles to enhance their usefulness, comfort, safety and visibility. Fenders with spoilers (mudflaps) protect the cyclist and moving parts from spray when riding through wet areas. In some countries (e.g. Germany, UK), fenders are called mudguards. The chainguards protect clothes from oil on the chain while preventing clothing from being caught between the chain and crankset teeth. Kick stands keep bicycles upright when parked, and bike locks deter theft. Front-mounted baskets, front or rear luggage carriers or racks, and panniers mounted above either or both wheels can be used to carry equipment or cargo. Pegs can be fastened to one, or both of the wheel hubs to either help the rider perform certain tricks, or allow a place for extra riders to stand, or rest.^{[citation needed]} Parents sometimes add rear-mounted child seats, an auxiliary saddle fitted to the crossbar, or both to transport children. Bicycles can also be fitted with a hitch to tow a trailer for carrying cargo, a child, or both.

Toe-clips and toestraps and clipless pedals help keep the foot locked in the proper pedal position and enable cyclists to pull and push the pedals. Technical accessories include cyclocomputers for measuring speed, distance, heart rate, GPS data etc. Other accessories include lights, reflectors, mirrors, racks, trailers, bags, water bottles and cages, and bell.^[66] Bicycle lights, reflectors, and helmets are required by law in some geographic regions depending on the legal code. It is more common to see bicycles with bottle generators, dynamos, lights, fenders, racks and bells in Europe. Bicyclists also have specialized form fitting and high visibility clothing.

Children’s bicycles may be outfitted with cosmetic enhancements such as bike horns, streamers, and spoke beads.^[67] Training wheels are sometimes used when learning to ride, but a dedicated balance bike teaches independent riding more effectively.^[68][69]

Bicycle helmets can reduce injury in the event of a collision or accident, and a suitable helmet is legally required of riders in many jurisdictions.^[70][71] Helmets may be classified as an accessory^[66] or as an item of clothing.^[72]

Bike trainers are used to enable cyclists to cycle while the bike remains stationary. They are frequently used to warm up before races or indoors when riding conditions are unfavorable.^[73]

Standards

A number of formal and industry standards exist for bicycle components to help make spare parts exchangeable and to maintain a minimum product safety.

The International Organization for Standardization (ISO) has a special technical committee for cycles, TC149, that has the scope of “Standardization in the field of cycles, their components and accessories with particular reference to terminology, testing methods and requirements for performance and safety, and interchangeability”.

The European Committee for Standardization (CEN) also has a specific Technical Committee, TC333, that defines European standards for cycles. Their mandate states that EN cycle standards shall harmonize with ISO standards. Some CEN cycle standards were developed before ISO published their standards, leading to strong European influences in this area. European cycle standards tend to describe minimum safety requirements, while ISO standards have historically harmonized parts geometry.^{[note 1]}

Maintenance and repair

Like all devices with mechanical moving parts, bicycles require a certain amount of regular maintenance and replacement of worn parts. A bicycle is relatively simple compared with a car, so some cyclists choose to do at least part of the maintenance themselves. Some components are easy to handle using relatively simple tools, while other components may require specialist manufacturer-dependent tools.

Many bicycle components are available at several different price/quality points; manufacturers generally try to keep all components on any particular bike at about the same quality level, though at the very cheap end of the market there may be some skimping on less obvious components (e.g. bottom bracket).

• There are several hundred assisted-service Community Bicycle Organizations worldwide.^[74] At a Community Bicycle Organization, laypeople bring in bicycles needing repair or maintenance; volunteers teach them how to do the required steps.
• Full service is available from bicycle mechanics at a local bike shop.
• In areas where it is available, some cyclists purchase roadside assistance from companies such as the Better World Club or the American Automobile Association.

Maintenance

The most basic maintenance item is keeping the tires correctly inflated; this can make a noticeable difference as to how the bike feels to ride. Bicycle tires usually have a marking on the sidewall indicating the pressure appropriate for that tire. Bicycles use much higher pressures than cars: car tires are normally in the range of 30 to 40 pounds per square inch (210 to 280 kPa), whereas bicycle tires are normally in the range of 60 to 100 pounds per square inch (410 to 690 kPa).

Another basic maintenance item is regular lubrication of the chain and pivot points for derailleurs and brake components. Most of the bearings on a modern bike are sealed and grease-filled and require little or no attention; such bearings will usually last for 10,000 miles (16,000 km) or more. The crank bearings require periodic maintenance, which involves removing, cleaning and repacking with the correct grease.

The chain and the brake blocks are the components which wear out most quickly, so these need to be checked from time to time, typically every 500 miles (800 km) or so. Most local bike shops will do such checks for free. Note that when a chain becomes badly worn it will also wear out the rear cogs/cassette and eventually the chain ring(s), so replacing a chain when only moderately worn will prolong the life of other components.

Over the longer term, tires do wear out, after 2,000 to 5,000 miles (3,200 to 8,000 km); a rash of punctures is often the most visible sign of a worn tire.

Repair

Very few bicycle components can actually be repaired; replacement of the failing component is the normal practice.

The most common roadside problem is a puncture of the tire’s inner tube. A patch kit may be employed to fix the puncture or the tube can be replaced, though the latter solution comes at a greater cost and waste of material.^[75] Some brands of tires are much more puncture-resistant than others, often incorporating one or more layers of Kevlar; the downside of such tires is that they may be heavier and/or more difficult to fit and remove.

Tools

Main article: Bicycle tools

There are specialized bicycle tools for use both in the shop and at the roadside. Many cyclists carry tool kits. These may include a tire patch kit (which, in turn, may contain any combination of a hand pump or CO₂ pump, tire levers, spare tubes, self-adhesive patches, or tube-patching material, an adhesive, a piece of sandpaper or a metal grater (for roughening the tube surface to be patched) and sometimes even a block of French chalk), wrenches, hex keys, screwdrivers, and a chain tool. Special, thin wrenches are often required for maintaining various screw-fastened parts, specifically, the frequently lubricated ball-bearing “cones”.^[76][77] There are also cycling-specific multi-tools that combine many of these implements into a single compact device. More specialized bicycle components may require more complex tools, including proprietary tools specific for a given manufacturer.

Social and historical aspects

The bicycle has had a considerable effect on human society, in both the cultural and industrial realms.^[78]

In daily life

See also: Cycling infrastructure and History of cycling infrastructure

Around the turn of the 20th century, bicycles reduced crowding in inner-city tenements by allowing workers to commute from more spacious dwellings in the suburbs. They also reduced dependence on horses. Bicycles allowed people to travel for leisure into the country, since bicycles were three times as energy efficient as walking and three to four times as fast.

In built-up cities around the world, urban planning uses cycling infrastructure like bikeways to reduce traffic congestion and air pollution.^[79] A number of cities around the world have implemented schemes known as bicycle sharing systems or community bicycle programs.^[80][81] The first of these was the White Bicycle plan in Amsterdam in 1965. It was followed by yellow bicycles in La Rochelle and green bicycles in Cambridge. These initiatives complement public transport systems and offer an alternative to motorized traffic to help reduce congestion and pollution.^[82] In Europe, especially in the Netherlands and parts of Germany and Denmark, bicycle commuting is common. In Copenhagen, a cyclists’ organization runs a Cycling Embassy that promotes biking for commuting and sightseeing. The United Kingdom has a tax break scheme (IR 176) that allows employees to buy a new bicycle tax free to use for commuting.^[83]

In the Netherlands all train stations offer free bicycle parking, or a more secure parking place for a small fee, with the larger stations also offering bicycle repair shops. Cycling is so popular that the parking capacity may be exceeded, while in some places such as Delft the capacity is usually exceeded.^[84] In Trondheim in Norway, the Trampe bicycle lift has been developed to encourage cyclists by giving assistance on a steep hill. Buses in many cities have bicycle carriers mounted on the front.

There are towns in some countries where bicycle culture has been an integral part of the landscape for generations, even without much official support. That is the case of Ílhavo, in Portugal.

In cities where bicycles are not integrated into the public transportation system, commuters often use bicycles as elements of a mixed-mode commute, where the bike is used to travel to and from train stations or other forms of rapid transit. Some students who commute several miles drive a car from home to a campus parking lot, then ride a bicycle to class. Folding bicycles are useful in these scenarios, as they are less cumbersome when carried aboard. Los Angeles removed a small amount of seating on some trains to make more room for bicycles and wheel chairs.^[85]

Some US companies, notably in the tech sector, are developing both innovative cycle designs and cycle-friendliness in the workplace. Foursquare, whose CEO Dennis Crowley “pedaled to pitch meetings … [when he] was raising money from venture capitalists” on a two-wheeler, chose a new location for its New York headquarters “based on where biking would be easy”. Parking in the office was also integral to HQ planning. Mitchell Moss, who runs the Rudin Center for Transportation Policy & Management at New York University, said in 2012: “Biking has become the mode of choice for the educated high tech worker”.^[86]

Bicycles offer an important mode of transport in many developing countries. Until recently, bicycles have been a staple of everyday life throughout Asian countries. They are the most frequently used method of transport for commuting to work, school, shopping, and life in general. In Europe, bicycles are commonly used.^[87] They also offer a degree of exercise to keep individuals healthy.^[88]

Bicycles are also celebrated in the visual arts. An example of this is the Bicycle Film Festival, a film festival hosted all around the world.

Poverty alleviation

This section is an excerpt from Bicycle poverty reduction.[edit]

Bicycle poverty reduction is the concept that access to bicycles and the transportation infrastructure to support them can dramatically reduce poverty.^{[89][90][91][92]} This has been demonstrated in various pilot projects in South Asia and Africa.^[93][94][95] Experiments done in Africa (Uganda and Tanzania) and Sri Lanka on hundreds of households have shown that a bicycle can increase the income of a poor family by as much as 35%.^[93][96][97]Transport, if analyzed for the cost–benefit analysis for rural poverty alleviation, has given one of the best returns in this regard. For example, road investments in India were a staggering 3–10 times more effective than almost all other investments and subsidies in rural economy in the decade of the 1990s. A road can ease transport on a macro level, while bicycle access supports it at the micro level. In that sense, the bicycle can be one of the most effective means to eradicate poverty in poor nations.

Female emancipation

See also: Bicycling and feminism

The safety bicycle gave women unprecedented mobility, contributing to their emancipation in Western nations. As bicycles became safer and cheaper, more women had access to the personal freedom that bicycles embodied, and so the bicycle came to symbolize the New Woman of the late 19th century, especially in Britain and the United States.^[7][99] The bicycle craze in the 1890s also led to a movement for so-called rational dress, which helped liberate women from corsets and ankle-length skirts and other restrictive garments, substituting the then-shocking bloomers.^[7]

The bicycle was recognized by 19th-century feminists and suffragists as a “freedom machine” for women. American Susan B. Anthony said in a New York World interview on 2 February 1896: “I think it has done more to emancipate woman than any one thing in the world. I rejoice every time I see a woman ride by on a wheel. It gives her a feeling of self-reliance and independence the moment she takes her seat; and away she goes, the picture of untrammelled womanhood.”^[100]: 859 In 1895 Frances Willard, the tightly laced president of the Woman’s Christian Temperance Union, wrote A Wheel Within a Wheel: How I Learned to Ride the Bicycle, with Some Reflections by the Way, a 75-page illustrated memoir praising “Gladys”, her bicycle, for its “gladdening effect” on her health and political optimism.^[98] Willard used a cycling metaphor to urge other suffragists to action.^[98]

In 1985, Georgena Terry started the first women-specific bicycle company. Her designs featured frame geometry and wheel sizes chosen to better fit women, with shorter top tubes and more suitable reach.^[101]

Economic implications

Bicycle manufacturing proved to be a training ground for other industries and led to the development of advanced metalworking techniques, both for the frames themselves and for special components such as ball bearings, washers, and sprockets. These techniques later enabled skilled metalworkers and mechanics to develop the components used in early automobiles and aircraft.

Wilbur and Orville Wright, a pair of businessmen, ran the Wright Cycle Company which designed, manufactured and sold their bicycles during the bike boom of the 1890s.^[102]

They also served to teach the industrial models later adopted, including mechanization and mass production (later copied and adopted by Ford and General Motors),^{[103][104][105]} vertical integration^[104] (also later copied and adopted by Ford), aggressive advertising^[106] (as much as 10% of all advertising in U.S. periodicals in 1898 was by bicycle makers),^[107] lobbying for better roads (which had the side benefit of acting as advertising, and of improving sales by providing more places to ride),^[105] all first practiced by Pope.^[105] In addition, bicycle makers adopted the annual model change^[103][108] (later derided as planned obsolescence, and usually credited to General Motors), which proved very successful.^[109]

Early bicycles were an example of conspicuous consumption, being adopted by the fashionable elites.^{[110][111][112][103][113][114][115][116]} In addition, by serving as a platform for accessories, which could ultimately cost more than the bicycle itself, it paved the way for the likes of the Barbie doll.^{[103][117][118]}

Bicycles helped create, or enhance, new kinds of businesses, such as bicycle messengers,^[119] traveling seamstresses,^[120] riding academies,^[121] and racing rinks.^[122][121] Their board tracks were later adapted to early motorcycle and automobile racing. There were a variety of new inventions, such as spoke tighteners,^[123] and specialized lights,^[118][123] socks and shoes,^[124] and even cameras, such as the Eastman Company‘s Poco.^[125] Probably the best known and most widely used of these inventions, adopted well beyond cycling, is Charles Bennett’s Bike Web, which came to be called the jock strap.^[126]

They also presaged a move away from public transit^[127] that would explode with the introduction of the automobile.

J. K. Starley’s company became the Rover Cycle Company Ltd. in the late 1890s, and then renamed the Rover Company when it started making cars. Morris Motors Limited (in Oxford) and Škoda also began in the bicycle business, as did the Wright brothers.^[128] Alistair Craig, whose company eventually emerged to become the engine manufacturers Ailsa Craig, also started from manufacturing bicycles, in Glasgow in March 1885.

In general, U.S. and European cycle manufacturers used to assemble cycles from their own frames and components made by other companies, although very large companies (such as Raleigh) used to make almost every part of a bicycle (including bottom brackets, axles, etc.) In recent years, those bicycle makers have greatly changed their methods of production. Now, almost none of them produce their own frames.

Many newer or smaller companies only design and market their products; the actual production is done by Asian companies. For example, some 60% of the world’s bicycles are now being made in China. Despite this shift in production, as nations such as China and India become more wealthy, their own use of bicycles has declined due to the increasing affordability of cars and motorcycles.^[129] One of the major reasons for the proliferation of Chinese-made bicycles in foreign markets is the lower cost of labor in China.^[130]

In line with the European financial crisis of that time, in 2011 the number of bicycle sales in Italy (1.75 million) passed the number of new car sales.^[131]

Environmental impact

One of the profound economic implications of bicycle use is that it liberates the user from motor fuel consumption. (Ballantine, 1972) The bicycle is an inexpensive, fast, healthy and environmentally friendly mode of transport. Ivan Illich stated that bicycle use extended the usable physical environment for people, while alternatives such as cars and motorways degraded and confined people’s environment and mobility.^[132] Currently, two billion bicycles are in use around the world. Children, students, professionals, laborers, civil servants and seniors are pedaling around their communities. They all experience the freedom and the natural opportunity for exercise that the bicycle easily provides. Bicycle also has lowest carbon intensity of travel.^[133]

Manufacturing

See also: List of bicycle manufacturing companies

The global bicycle market is $61 billion in 2011.^[134] As of 2009, 130 million bicycles were sold every year globally and 66% of them were made in China.^[135]

Year	production (M)	sales (M)
2000	14.531	18.945
2001	13.009	17.745
2002	12.272	17.840
2003	12.828	20.206
2004	13.232	20.322
2005	13.218	20.912
2006	13.320	21.033
2007	13.086	21.344
2008	13.246	20.206
2009	12.178	19.582
2010	12.241	20.461
2011	11.758	20.039
2012	11.537	19.719
2013	11.360	19.780
2014	11.939	20.234

Country	Production (M)	Parts (M€)	Sales (M)	Avg	Sales (M€)
Italy	2.729	491	1.696	288	488.4
Germany	2.139	286	4.100	528	2164.8
Poland	.991	58	1.094	380	415.7
Bulgaria	.950	9	.082	119	9.8
The Netherlands	.850	85	1.051	844	887
Romania	.820	220	.370	125	46.3
Portugal	.720	120	.340	160	54.4
France	.630	170	2.978	307	914.2
Hungary	.370	10	.044	190	8.4
Spain	.356	10	1.089	451	491.1
Czech Republic	.333	85	.333	150	50
Lithuania	.323	0	.050	110	5.5
Slovakia	.210	9	.038	196	7.4
Austria	.138	0	.401	450	180.5
Greece	.108	0	.199	233	46.4
Belgium	.099	35	.567	420	238.1
Sweden	.083	0	.584	458	267.5
Great Britain	.052	34	3.630	345	1252.4
Finland	.034	32	.300	320	96
Slovenia	.005	9	.240	110	26.4
Croatia	0	0	.333	110	36.6
Cyprus	0	0	.033	110	3.6
Denmark	0	0	.470	450	211.5
Estonia	0	0	.062	190	11.8
Ireland	0	0	.091	190	17.3
Latvia	0	0	.040	110	4.4
Luxembourg	0	0	.010	450	4.5
Malta	0	0	.011	110	1.2
EU 28	11.939	1662	20.234	392	7941.2

Legal requirements

Main article: Bicycle law

Early in its development, as with automobiles, there were restrictions on the operation of bicycles. Along with advertising, and to gain free publicity, Albert A. Pope litigated on behalf of cyclists.^[105]

The 1968 Vienna Convention on Road Traffic of the United Nations considers a bicycle to be a vehicle, and a person controlling a bicycle (whether actually riding or not) is considered an operator or driver.^{[citation needed][137][138]} The traffic codes of many countries reflect these definitions and demand that a bicycle satisfy certain legal requirements before it can be used on public roads. In many jurisdictions, it is an offense to use a bicycle that is not in a roadworthy condition.^[139][140]

In some countries, bicycles must have functioning front and rear lights when ridden after dark.^[141][142]

Some countries require child and/or adult cyclists to wear helmets, as this may protect riders from head trauma. Countries which require adult cyclists to wear helmets include Spain, New Zealand and Australia. Mandatory helmet wearing is one of the most controversial topics in the cycling world, with proponents arguing that it reduces head injuries and thus is an acceptable requirement, while opponents argue that by making cycling seem more dangerous and cumbersome, it reduces cyclist numbers on the streets, creating an overall negative health effect (fewer people cycling for their own health, and the remaining cyclists being more exposed through a reversed safety in numbers effect).^[143]

Theft

Main article: Bicycle theft