Editing Bicycle (section)

==Technical aspects==
{{More citations needed section|date=June 2021}} 
[[File:Firefighter bicycle.jpg|thumb|Firefighter bicycle]]

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.<ref>{{Cite web |title=Game changers {{!}} 12 innovations that changed road cycling |url=https://www.bikeradar.com/features/cycling-innovations/ |access-date=10 January 2023 |website=BikeRadar |date=10 June 2021 |language=en}}</ref>

===Types===
{{Main|List of bicycle types}}
[[File:A man riding an electric bicycle.jpg|thumb|left|A man riding an [[electric bicycle]]]]

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 bicycle]]s, [[mountain bicycle]]s, [[racing bicycle]]s, [[touring bicycle]]s, [[hybrid bicycle]]s, [[cruiser bicycle]]s, and [[BMX bike]]s. Less common are [[tandem bicycle|tandems]], [[Lowrider bicycle|low riders]], [[tall bike]]s, [[Fixed-gear bicycle|fixed gear]], [[folding bicycle|folding models]], [[amphibious bicycles]], [[cargo bike]]s, [[recumbent bicycle|recumbents]] and [[electric bicycles]].

[[Unicycle]]s, [[tricycle]]s and [[Quadracycle (human-powered vehicle)|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|Bicycle and motorcycle dynamics}}
[[File:Jersey Town Criterium 2011 81.jpg|thumb|upright|A cyclist leaning in a turn]]

A bicycle stays upright while moving forward by being steered so as to keep its [[center of mass]] over the wheels.<ref name="NS2581">{{cite journal|last=Various|date=9 December 2006|title=Like falling off|url=https://www.newscientist.com/article/mg19225812.400|url-status=dead|journal=New Scientist|issue=2581|page=93|archive-url=https://web.archive.org/web/20081204070845/https://www.newscientist.com/article/mg19225812.400|archive-date=4 December 2008|access-date=27 January 2009}}</ref> This steering is usually provided by the rider, but under certain conditions may be provided by the bicycle itself.<ref name=MPRS>{{cite journal
| journal = [[Proceedings of the Royal Society A]]
| volume = 463
| issue = 2084
| year = 2007
| pages = 1955–82
| title = Linearized dynamics equations for the balance and steer of a bicycle: a benchmark and review
| last1 = Meijaard
| doi = 10.1098/rspa.2007.1857
| first1 = J.P.
| last2 = Papadopoulos
| first2 = Jim M.
| last3 = Ruina
| first3 = Andy
| last4 = Schwab
| first4 = A.L.
| bibcode=2007RSPSA.463.1955M
| s2cid = 18309860
 | issn=1364-5021 }}</ref>

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<ref name="Wilson">{{cite book
| title = Bicycling Science
|url=https://archive.org/details/isbn_9780262731546
| url-access = registration
| edition = Third
| last = Wilson
| first = David Gordon
|author2=Jim Papadopoulos
| year = 2004
| publisher = The MIT Press
| isbn = 978-0-262-73154-6
| pages = [https://archive.org/details/isbn_9780262731546/page/270 270–72]}}</ref> or indirectly by leaning the bicycle.<ref name="fajans">{{cite journal|last=Fajans|first=Joel|date=July 1738|title=Steering in bicycles and motorcycles|url=http://socrates.berkeley.edu/~fajans/pub/pdffiles/SteerBikeAJP.PDF|url-status=dead|journal=American Journal of Physics|volume=68|issue=7|pages=654–59|bibcode=2000AmJPh..68..654F|doi=10.1119/1.19504|archive-url=https://web.archive.org/web/20060901081011/http://socrates.berkeley.edu/~fajans/pub/pdffiles/SteerBikeAJP.PDF|archive-date=1 September 2006|access-date=4 August 2006}}</ref>

Short-wheelbase or tall bicycles, when braking, can generate enough stopping force at the front wheel to flip longitudinally.<ref>{{cite book
| title = Motorcycle Dynamics
| edition = Second
| last = Cossalter
| first = Vittore
| year = 2006
| publisher = [[Lulu (company)|Lulu]]
| isbn = 978-1-4303-0861-4
| pages = 241–342}}</ref> 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|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.<ref>S.S. Wilson, "[https://www.scientificamerican.com/article/bicycle-technology Bicycle Technology]", ''[[Scientific American]]'', March 1973</ref> 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%.<ref>{{cite web |title=Pedal power probe shows bicycles waste little energy |url=http://www.jhu.edu/~gazette/1999/aug3099/30pedal.html |work=Johns Hopkins Gazette |date=30 August 1999}}</ref><ref name="whitt">{{cite book
| title = Bicycling Science
| edition = Second
| last = Whitt
| first = Frank R.
|author2=David G. Wilson
| year = 1982
| publisher = Massachusetts Institute of Technology
| isbn = 978-0-262-23111-4
| pages = 277–300}}</ref> 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 {{Convert|16|–|24|km/h|abbr=on|0}} 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 [[aerodynamic]]ally streamlined position. Drag can also be reduced by covering the bicycle with an aerodynamic [[Bicycle fairing|fairing]]. The fastest recorded unpaced speed on a flat surface is {{Convert|144.18|km/h|abbr=on}}.<ref name="upi">{{cite web
|url=http://www.ibtimes.co.uk/aerovelo-eta-bullet-shaped-bike-sets-new-human-powered-speed-world-record-1582628
| title = AeroVelo Eta: bullet-shaped bike sets new human-powered speed record
| date = 21 September 2016
| website = International Business Times
| access-date = 29 November 2016}}</ref>

In addition, the [[carbon dioxide]] generated in the production and transportation of the food required by the bicyclist, per mile traveled, is less than {{Fraction|1|10}} that generated by energy efficient motorcars.<ref>{{cite web |url=http://www.kenkifer.com/bikepages/advocacy/bike_co2.htm |title=How Much Do Bicycles Pollute? Looking at the Carbon Dioxide Produced by Bicycles |publisher=Kenkifer.com |date=20 November 1999 |access-date=24 October 2011 |archive-url=https://web.archive.org/web/20111115130508/http://www.kenkifer.com/bikepages/advocacy/bike_co2.htm |archive-date=15 November 2011 |url-status=dead }}</ref>
<gallery mode="packed" heights="160px">
Image:Corsa bacchetta.jpg|A [[recumbent bicycle]] 
File:Wooden bicycle for young child.jpg|[[Balance bicycle]] for young children
</gallery>