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{{Short description|Method of changing gears on a bicycle}}
[[File:Electronic front derailleur.jpg|right|thumb|Electronic front derailleur (Shimano Di2)]]
[[File:Electronic shifting control unit and battery pack.jpg|right|thumb|Electronic shifting control unit and battery pack mounted to bottom of bottom bracket and left chain stay]]
[[File:Electronic front derailleur.jpg|thumb|upright|Electronic front derailleur (Shimano Di2)]]
[[File:Campagnolo Record EPS Rear Derailleur.jpg|right|thumb|Electronic rear derailleur (Campagnolo Record EPS)]]
An '''electronic gear-shifting system''' is a method of changing gears on a [[bicycle]], which enables riders to shift with electronic [[switch]]es instead of using conventional [[shifter (bicycle part)|control levers]]. The switches are connected by wire or [[wireless]]ly to a [[battery pack]] and to a small [[electric motor]] that drives the [[derailleur gears|derailleur]], switching the [[Bicycle chain|chain]] from [[Cogset|cog]] to cog. An electronic system can switch gears faster, and because the system does not use [[Bowden cable]]s and can calibrate itself, it may require less maintenance.<ref name = Best>{{cite web
| author = Best, Paul
| title = Shimano's Dura-Ace Di2 electronic shifting to give road racers a time advantage
| date = 08 04 2009
| url = http://www.gizmag.com/shimano-dura-ace-di2-electronic-shift/11407/
| publisher = Gizmag
| accessdate = 2010-02-10}}</ref>


An '''electronic gear-shifting system''' is a method of changing gears on a [[bicycle]], which enables riders to shift with electronic [[switch]]es instead of using conventional [[shifter (bicycle part)|control levers]] and mechanical cables. The switches are connected by wire or [[wireless]]ly to a [[battery pack]] and to a small [[electric motor]] that drives the [[derailleur gears|derailleur]], switching the [[Bicycle chain|chain]] from [[Cogset|cog]] to cog. An electronic system can switch gears faster and, because the system does not use [[Bowden cable]]s and can calibrate itself, it may require less maintenance.<ref name = Best>{{cite web | author = Best, Paul | title = Shimano's Dura-Ace Di2 electronic shifting to give road racers a time advantage | date = 2009-04-08 | url = http://www.gizmag.com/shimano-dura-ace-di2-electronic-shift/11407/ | publisher = Gizmag | accessdate = 2010-02-10}}</ref>
==History==
In 1990 the [[Japan]]ese bike component manufacturer [[SunTour]] introduced the Browning Electronic AccuShift Transmission (''SunTour BEAST'') - a triple [[chainset]] system for mountain bikes in which one quarter of the circle is hinged along a radius. During shifting, this segment is pushed sideways by a [[relay]] operated mechanism like a [[railroad switch]] and picks up the chain that is currently running on the next [[gear|cog]].<ref>{{cite web
| url = http://www.disraeligears.co.uk/Site/Browning_derailleurs_page_2.html
| title = Browning
| author = Michael Sweatman
| accessdate = 2012-09-10}}</ref>


== History ==
In 1992 the French manufacturer [[Mavic]] introduced their first electronically controlled gear shift mechanism called ''Zap'' at the [[1992 Tour de France]]. It was a prototype, but it achieved neither technical success nor commercial application. A development of this was used by [[Chris Boardman]] to win the opening time trial (''prologue'') of the [[1997 Tour de France]].<ref name = "Austen"/>
[[File: Electronic shifting control unit and battery pack.jpg|thumb|left|upright|Electronic shifting control unit and battery pack mounted to the bottom of bottom bracket and left chain stay]]
[[File:Campagnolo Record EPS Rear Derailleur.jpg|thumb|upright|Electronic rear derailleur (Campagnolo Record EPS)]]
[[File: Archer Remote.jpg|thumb|upright|Handlebar mounted controls]]


In 1990, the [[Japan]]ese bike component manufacturer [[SunTour]] introduced the Browning Electronic AccuShift Transmission (''SunTour BEAST'') - a triple [[crankset/chainset]] system for mountain bikes in which one quarter of the circle is hinged along a radius. During shifting, this segment is pushed sideways by a [[relay]] operated mechanism like a [[railroad switch]] and picks up the chain that is currently running on the next [[gear|cog]].<ref>{{cite web | url = http://www.disraeligears.co.uk/Site/Browning_derailleurs_page_2.html | title = Browning | author = Michael Sweatman | accessdate = 2012-09-10}}</ref>
In 1994 [[SRAM Corporation|Sachs]] introduced the Speedtronic.<ref name="SRAM Hist">{{cite web
| url = http://www.sram.com/company/history
| title = SRAM History
| accessdate = 2010-02-17}}</ref><ref name = Phillips/>


In 1992 the French manufacturer [[Mavic (bicycle parts company)|Mavic]] introduced their first electronically controlled gear shift mechanism called ''Zap'' at the [[1992 Tour de France]]. It was a prototype, but it achieved neither technical success nor commercial application. A development of this was used by [[Chris Boardman]] to win the opening time trial (''prologue'') of the [[1997 Tour de France]].<ref name = "Austen"/>
In 1999 Mavic introduced the ''Mektronic'', its second electronic shift system, which suffered from reliability issues and was subsequently discontinued.<ref name = "Austen"/>


In 1994 [[SRAM Corporation|Sachs]] introduced the Speedtronic.<ref name="SRAM Hist">{{cite web | url=http://www.sram.com/company/history | title=SRAM History | accessdate=2010-02-17 | url-status=dead | archiveurl=https://web.archive.org/web/20091006024600/http://www.sram.com/company/history | archivedate=2009-10-06 }}</ref><ref name = Phillips/>[[File:Deragliatore elettronico.jpg|thumb|upright|Mavic Mektronic rear derailleur]]In 1999 Mavic introduced the ''Mektronic'', its second electronic shift system, which suffered from reliability issues and was subsequently discontinued.<ref name="Austen" />
During the 2000s both [[Shimano]] and [[Campagnolo]] (2005)<ref>{{cite web
| url = http://velonews.competitor.com/2009/09/bikes-tech/campagnolos-magic-lives-on-in-vicenza_97867
| title = Campagnolo's Magic Lives on in Vicenza
| publisher = VeloNews
| date = September 15, 2009
| author = Lennard Zinn
| accessdate = 2010-02-17}}</ref> experimented with electronic shifting in professional cycle races.<ref name = "Austen"/>


In 2001 Shimano introduced a set of trekking components called Di2 (Digital Integrated Intelligence), which included electronic shifting and automatic adaption of front and rear derailleur to riding speed.
The first commercial electronic gear shift system for [[road bicycle]]s was introduced by Shimano in 2009, the ''Di2''.<ref name = "Austen"/> Three professional teams used the Di2 in the 2009 [[Tour of California]]: [[Team Columbia High Road|Columbia High Road]], [[Garmin Slipstream]], and [[Rabobank (cycling team)|Rabobank]];<ref name = "Austen"/> and several teams and riders, including [[George Hincapie]], used it during the 2009 [[Tour de France]]<ref>{{cite web
| url = http://www.roadcyclinguk.com/gear-news/pro-riders-on-shimano-dura-ace-di2.html
| title = Pro riders on Shimano Dura-Ace Di2
| author = David Arthur
| date = 9 July 2009
| publisher = RoadCyclingUK
| accessdate = 2010-02-12}}</ref>


During the 2000s both [[Shimano]] and [[Campagnolo]] (2005)<ref>{{cite magazine | url = http://velonews.competitor.com/2009/09/bikes-tech/campagnolos-magic-lives-on-in-vicenza_97867 | title = Campagnolo's Magic Lives on in Vicenza | magazine = VeloNews | date = September 15, 2009 | author = Lennard Zinn | accessdate = 2010-02-17}}</ref> experimented with electronic shifting in professional cycle races.<ref name="Austen" />
Also in 2009 [[Giant Manufacturing|Giant]] released a bicycle equipped with the Shimano Di2<ref name = "Austen"/><ref>{{cite web

| url = http://www.giant-bicycles.com/en-AU/bikes/road/2327/36144/
The first commercially successful electronic gear shift system for [[road bicycle]]s was introduced by Shimano in 2009, the ''Di2''.<ref name="Austen" /> Three professional teams used the Di2 in the 2009 [[Tour of California]]: [[Team Columbia High Road|Columbia High Road]], [[Garmin Slipstream]], and [[Rabobank (cycling team)|Rabobank]];<ref name="Austen" /> and several teams and riders, including [[George Hincapie]], used it during the 2009 [[Tour de France]]<ref>{{cite web | url = http://www.roadcyclinguk.com/gear-news/pro-riders-on-shimano-dura-ace-di2.html | title = Pro riders on Shimano Dura-Ace Di2 | author = David Arthur | date = 9 July 2009 | publisher = RoadCyclingUK | accessdate = 2010-02-12}}</ref>
| title = TSR Advanced SL LTD

| publisher = [[Giant Manufacturing]]
| accessdate = 2010-02-12}}</ref> and [[Trek Bicycle Corporation|Trek]] began providing a battery mount and Di2-specific cable routing and stops on its Madone frames.<ref>{{cite web
Also in 2009 [[Giant Manufacturing|Giant]] released a bicycle equipped with the Shimano Di2<ref name="Austen" /><ref>{{cite web | url = http://www.giant-bicycles.com/en-AU/bikes/road/2327/36144/ | title = TSR Advanced SL LTD | publisher = [[Giant Manufacturing]] | accessdate = 2010-02-12}}</ref> and [[Trek Bicycle Corporation|Trek]] began providing a battery mount and Di2-specific cable routing and stops on its Madone frames.<ref>{{cite web | url = http://www.trekbikes.com/us/en/bikes/road/madone/6_series/technology/ | title = Madone 6 Series | publisher = [[Trek Bicycle Corporation]] | accessdate = 2010-02-12}}</ref>

| url = http://www.trekbikes.com/us/en/bikes/road/madone/6_series/technology/
In 2015 SRAM announced its wireless electronic groupset called, SRAM RED eTap. The group was released in Spring of 2016 and is available on complete bikes and through aftermarket SRAM component dealers.<ref>{{Cite web |url=https://sramroadsupport.zendesk.com/hc/en-us/articles/206573428-When-is-SRAM-RED-eTap-available- |title=When is SRAM RED eTap available? – SRAM Road Electronic Groupset FAQ |access-date=2015-09-11 |archive-date=2015-09-07 |archive-url=https://web.archive.org/web/20150907215809/https://sramroadsupport.zendesk.com/hc/en-us/articles/206573428-When-is-SRAM-RED-eTap-available- |url-status=dead }}</ref><ref>{{Cite web |url=https://sramroadsupport.zendesk.com/hc/en-us/articles/206573508-Where-is-SRAM-RED-eTap-available- |title=Where is SRAM RED eTap available? – SRAM Road Electronic Groupset FAQ |access-date=2015-09-11 |archive-date=2015-09-19 |archive-url=https://web.archive.org/web/20150919094635/https://sramroadsupport.zendesk.com/hc/en-us/articles/206573508-Where-is-SRAM-RED-eTap-available- |url-status=dead }}</ref>
| title = Madone 6 Series

| publisher = [[Trek Bicycle Corporation]]
A wireless system that can be retrofitted onto any bicycle was announced in 2016.<ref>{{cite web | url = http://newatlas.com/top-ten-cycling-innovations-2016/46837/ | title = The 10 best cycling innovations of 2016 | author = Ben Coxworth | date = December 7, 2016 | publisher = New Atlas | accessdate = 2017-06-04}}</ref> The front and rear derailleurs remain in place, while a wireless gear-change controller is added to the handlebar, with configuration of the system via an iOS/Android app, and customization can be added to the button controllers via the Bluetooth app.<ref>{{cite web | url = https://www.bikerumor.com/2016/09/26/xshifter-brings-wireless-electronic-shifting-bike-derailleur/ | title = X-Shifter's universal wireless shifting kit goes live | author = Tyler Benedict | date = November 2, 2016 | publisher = Bike Rumor | accessdate = 2017-06-04}}</ref>
| accessdate = 2010-02-12}}</ref>


== Implementation ==
== Implementation ==
[[File:Electronic rear derailleur.jpg|thumb|left|Electronic rear derailleur]]
As of 2009, one system was commercially available from a major [[List of bicycle part manufacturing companies|parts manufacturer]]: [[Shimano]]'s Di2 ([[Shimano#Road bicycle groupsets|Dura-Ace 7970]]) for [[road bicycle]]s. While the traditional method of gear shifting uses mechanical control levers that pull and release Bowden cables and spring-loaded derailleurs, Di2 is controlled by solid-state switches located either in the [[Shifter (bicycle part)#Brake/Shift Levers|integrated shift levers]] and/or at the end of [[Triathlon bars#Triathlon or aero|time trial bars]]. The switches send signals through a wiring harness to a battery pack, placed near the [[bottom bracket]]. The rechargeable [[lithium-ion battery]] pack supplies power to the derailleur motors, which move the derailleurs via [[Worm drive|worm gears]]. [[Shimano]] estimates that their 7.4-volt battery pack can last up to {{convert|1000|km}} per charge.<ref>{{cite web
[[File:Electronic shift lever.jpg|thumb|upright|Electronic shift lever]]
| author = Crowe, Paul
| title = Electronic Shift By Wire on Bicycle
| publisher = The Kneeslider
| accessdate = 2010-02-09
| url = http://thekneeslider.com/archives/2008/08/01/electronic-shift-by-wire-on-bicycles/}}</ref> The system also has an LED light to warn when it needs a charge.<ref name = "Huang">{{cite web
| url = http://www.bikeradar.com/gear/category/components/gear-shifters/product/dura-ace-di2-transmission-34981
| title = Shimano Dura-Ace Di2 transmission
| publisher = BikeRadar.com
| author = James Huang
| date = Aug 2009
| accessdate = 2010-02-13}}</ref>


As of 2009, one system was commercially available from a major [[List of bicycle part manufacturing companies|parts manufacturer]]: [[Shimano]]'s Di2 ([[Shimano#Road bicycle groupsets|Dura-Ace 7970]]) for [[road bicycle]]s. While the traditional method of gear shifting uses mechanical control levers that pull and release Bowden cables and spring-loaded derailleurs, Di2 is controlled by electronic switches located either in the [[Shifter (bicycle part)#Brake/Shift Levers|integrated shift levers]] and/or at the end of [[Triathlon bars#Triathlon or aero|time trial bars]]. The switches send signals through a wiring harness to a battery pack, placed near the [[bottom bracket]]. The rechargeable [[lithium-ion battery]] pack supplies power to the derailleur motors, which move the derailleurs via [[Worm drive|worm gears]]. [[Shimano]] estimates that their 7.4-volt battery pack can last up to {{convert|1000|km}} per charge.<ref>{{cite web | author = Crowe, Paul | title = Electronic Shift By Wire on Bicycle | publisher = The Kneeslider | accessdate = 2010-02-09 | url = http://thekneeslider.com/archives/2008/08/01/electronic-shift-by-wire-on-bicycles/}}</ref> The system also has an LED light to warn when it needs a charge.<ref name="Huang">{{cite web | url = http://www.bikeradar.com/gear/category/components/gear-shifters/product/dura-ace-di2-transmission-34981 | title = Shimano Dura-Ace Di2 transmission | publisher = BikeRadar.com | author = James Huang | date = Aug 2009 | accessdate = 2010-02-13}}</ref>
The [[Derailleur gears#Rear derailleurs|rear derailleur]] has shift times similar to mechanical systems and a break-away system to protect it in case of a crash.<ref name = "Huang"/> The [[Derailleur gears#Front derailleurs|front derailleur]], however, switches gears almost 30% faster than Dura-Ace’s mechanical counterpart, with most of the improvement in shifting the front derailleur.<ref name = Best/> On traditional bikes, the front derailleur is problematic because the chain can be under tension and has to make a large vertical jump between [[crankset|chainrings]]. The electronic system's controlled motion overcomes these problems. The Di2 can also trim the front derailleur to eliminate chain rub and calibrate itself to adjust for wear and tear.<ref name = Hagerman>{{cite web
| author = Hagerman, Eric
| publisher = [[Wired (magazine)|Wired]]
| title = Shimano Shuns Cables for Full Electronic Shifting
| date = 2008-07-31
| accessdate = 2010-02-09
| url = http://www.wired.com/gadgets/miscellaneous/news/2008/07/shimano?currentPage=1}}</ref> Finally, the entire 7970 [[groupset]] weighs approximately {{convert|113|g}} less than the 7800 it replaces but {{convert|68|g}} more than the new 7900.<ref>{{cite web
| author = Cole, Matthew
| title = Shimano unveils Dura-Ace Di2 electronic groupset
| publisher = BikeRadar.com
| date = 01 08 2008
| accessdate = 2010-02-09
| url = http://www.bikeradar.com/news/article/shimano-unveils-dura-ace-di2-electronic-groupset-17847}}</ref>


The [[Derailleur#Rear derailleurs|rear derailleur]] has shift times similar to mechanical systems and a break-away system to protect it in case of a crash.<ref name="Huang" /> The [[Derailleur#Front derailleurs|front derailleur]], however, switches gears almost 30% faster than Dura-Ace’s mechanical counterpart.<ref name="Best" /> On traditional bikes, the front derailleur is problematic because the chain can be under tension and has to make a large vertical jump between [[crankset|chainrings]]. The electronic system's controlled motion overcomes these problems. The Di2 can also trim the front derailleur to eliminate chain rub and calibrate itself to adjust for wear and tear.<ref name="Hagerman">{{cite magazine | author = Hagerman, Eric | magazine = [[Wired (magazine)|Wired]] | title = Shimano Shuns Cables for Full Electronic Shifting | date = 2008-07-31 | accessdate = 2010-02-09 | url = https://www.wired.com/gadgets/miscellaneous/news/2008/07/shimano?currentPage=1}}</ref> Finally, the entire 7970 [[groupset]] weighs approximately {{convert|113|g}} less than the 7800 it replaces but {{convert|68|g}} more than the new 7900.<ref>{{cite web | author = Cole, Matthew | title = Shimano unveils Dura-Ace Di2 electronic groupset | publisher = BikeRadar.com | date = 2008-08-01 | accessdate = 2010-02-09 | url = http://www.bikeradar.com/news/article/shimano-unveils-dura-ace-di2-electronic-groupset-17847}}</ref>
In 2011 Shimano introduced the Ultegra Di2<ref>{{cite web
| url = http://www.bikeradar.com/road/gear/article/shimano-ultegra-di2-first-look-30616
| title = Shimano Ultegra Di2 – First look
| author = Richard Tyler
| date = Jun 20, 2011
| publisher = BikeRadar.com
| accessdate = 2012-09-10}}</ref> electronic gear change set, a cheaper version of the electronic Dura-Ace system. This set seemed to provide an electronic option within reach of a wider audience. [[Campagnolo]] introduced their first system of electronic shifting in the same year.<ref>{{cite web
| url = http://www.bikeradar.com/news/article/campagnolo-show-off-new-electronic-gear-system-28244
| title = Campagnolo show off new electronic gear system
| author = Stephen Farrand
| date = Oct 25, 2010
| publisher = BikeRadar.com
| accessdate = 2012-09-10}}</ref> By 2012 Campagnolo had three electronic shifting systems available.<ref>{{cite web
| url = http://www.bikeradar.com/road/news/article/campagnolo-athena-eps-11-speed-launched-34613/
| title = Campagnolo Athena EPS 11-speed launched
| author = Robin Wilmott
| date = Jul 17, 2012
| publisher = BikeRadar.com
| accessdate = 2012-09-10}}</ref> Cyclists began to see a growing range of electronic alternatives to traditional mechanical shifting for [[derailleur gears]].


In 2011 Shimano introduced the [[Shimano Ultegra|Ultegra Di2]]<ref>{{cite web | url = http://www.bikeradar.com/road/gear/article/shimano-ultegra-di2-first-look-30616 | title = Shimano Ultegra Di2 – First look | author = Richard Tyler | date = Jun 20, 2011 | publisher = BikeRadar.com | accessdate = 2012-09-10}}</ref> electronic gear change set, a cheaper version of the electronic Dura-Ace system. This set seemed to provide an electronic option within reach of a wider audience.
A wireless system has been developed by Tiso.<ref>{{cite web
| url = http://www.gizmag.com/tiso-wireless-bicycle-gear-shifting/25496/
| title = Tiso unveils wireless electronic gear-shifting for road bikes
| author = Ben Coxworth
| date = December 18, 2012
| publisher = GizMag
| quote = Shift signals are transmitted from the shifters to the control unit via Bluetooth – Shimano and Campagnolo’s systems, by contrast, use electrical wiring.
| accessdate = 2013-11-27}}</ref>


[[Campagnolo]] introduced their first system of electronic shifting, EPS, in the same year.<ref>{{cite web | url = http://www.bikeradar.com/news/article/campagnolo-show-off-new-electronic-gear-system-28244 | title = Campagnolo show off new electronic gear system | author = Stephen Farrand | date = Oct 25, 2010 | publisher = BikeRadar.com | accessdate = 2012-09-10}}</ref> By 2012 Campagnolo had three electronic shifting groupsets available.<ref>{{cite web | url = http://www.bikeradar.com/road/news/article/campagnolo-athena-eps-11-speed-launched-34613/ | title = Campagnolo Athena EPS 11-speed launched | author = Robin Wilmott | date = Jul 17, 2012 | publisher = BikeRadar.com | accessdate = 2012-09-10}}</ref> Cyclists began to see a growing range of electronic alternatives to traditional mechanical shifting for [[derailleur gears]].
== Advantages ==

<gallery widths="360" heights="270">
File:Shimano Di2 9070 Back EN.jpg|Parts of a wired system - rear
File:Shimano Di2 9070 Front EN.jpg|Parts of a wired system - front
</gallery>

== Wireless shifting ==
[[File:Electronic front derailleur (front view).jpg|thumb|upright|left|Electronic front derailleur (front view)]]
[[File:2017 SRAM RED eTap WiFLi Rear Derailleur.jpg|thumb|Production SRAM RED eTap rear derailleur installed on bike (2017)]]
[[File:SRAM RED eTap HRD Lever.jpg|thumb|upright|SRAM RED eTap HRD brake lever]]A wireless system was announced by Tiso in 2012, but this did not achieve widespread use.<ref>{{cite web | url = http://www.gizmag.com/tiso-wireless-bicycle-gear-shifting/25496/ | title = Tiso unveils wireless electronic gear-shifting for road bikes | author = Ben Coxworth | date = December 18, 2012 | publisher = GizMag | quote = Shift signals are transmitted from the shifters to the control unit via Bluetooth and/or another unspecified type of radio protocol – Shimano and Campagnolo’s systems, by contrast, use electrical wiring. | accessdate = 2015-09-12}}</ref>

In August 2015 [[SRAM Corporation]] announced its wireless shifting system, eTap.<ref>{{cite web | url = http://www.bikeradar.com/road/news/article/sram-red-etap-ushers-in-wireless-shifting-era-45095 | title = SRAM Red eTap ushers in wireless shifting era | author = Warren Rossiter | date = August 26, 2015 | publisher = BikeRadar | accessdate = 2015-09-12}}</ref> The system had been extensively developed and secretly tested over several years from initial design to a stage win in the 2015 Tour de France. The front and rear derailleurs use direct-mount batteries and communicate wirelessly with the shifters through a proprietary wireless protocol developed by SRAM called, Airea (pronounced: area). A set of small satellite shifter buttons, called Blips, can be connected to the shift levers or aero shift module (BlipBox) and placed anywhere along the handlebars as part of the system. A maximum of four Blips can be used per bike. The company also took the opportunity to introduce a new shifting convention with this system. The right lever shifts the rear derailleur outboard, the left lever shifts the rear derailleur inboard, and pressing both levers together shifts the front derailleur. SRAM made the groupset available for purchase on complete bikes and as aftermarket components sold through dealers from Spring 2016. Eventually, extension of the system is expected to the company's lower group sets, such as SRAM Force. In May 2016 the company announced a hydraulic disc brake version of its wireless road group called SRAM RED eTap HRD. The new brakes make use of a hydraulic lever design with both lever reach adjustment and lever contact point adjustment, a first for road disc brakes.

== Advantages and disadvantages ==
An electronic system can have several advantages over a comparable mechanical system:
An electronic system can have several advantages over a comparable mechanical system:

* eliminate the need for the rider to switch hand positions in order to shift (in the case of Shimano dual control levers for time trial and triathlon)<ref name = Best/>
* eliminate the need for the rider to switch hand positions in order to shift<ref name="Best" />
* allow for an accurate and effortless shift, even in difficult circumstances, such as if the rider has cold hands or is completely exhausted
* allow for an accurate and effortless shift, even in difficult circumstances, such as if the rider has cold hands or is completely exhausted
* shifting performance is not affected by contaminated, stretched, or worn Bowden cables
* shifting performance is not affected by contaminated, stretched, or worn Bowden cables
* automatic trim function can eliminate chain rub<ref name = Best/>
* automatic trim function can eliminate chain rub<ref name="Best" />
* shifts can be timed to occur at a particular point in the cassette or chainring rotation, making best and smoothest use of ramps and cutouts in the sprocket teeth
* the smoothness of electronics can reduce the shock on drivetrain components<ref name = Phillips>{{cite web
* the front and rear shift pattern on a bike with multiple chainrings can be programmed to make best use of the gear progression, avoid duplicate ratios and relieve the rider of the need to decide what combination of front and rear sprockets to employ
| author = Phillips, Matt
* the smoothness of electronics can reduce the shock on drivetrain components<ref name="Phillips">{{cite web|author=Phillips, Matt |title=The Shift to Electric |date=9 Feb 2010 |publisher=[[Bicycling Magazine]] |url=http://www.bicycling.com/article/0,6610,s1-1-8-18392-1,00.html |accessdate=2010-02-10 |url-status=dead |archiveurl=https://web.archive.org/web/20090417033053/http://www.bicycling.com/article/0,6610,s1-1-8-18392-1,00.html |archivedate=April 17, 2009 }}</ref>
| title = The Shift to Electric
| date = 9 Feb 2010
| publisher = ''[[Bicycling Magazine]]''
| url = http://www.bicycling.com/article/0,6610,s1-1-8-18392-1,00.html
| accessdate = 2010-02-10}} {{Dead link|date=October 2010|bot=H3llBot}}</ref>


== Disadvantages ==
An electronic system may have some disadvantages when compared to a mechanical system:
An electronic system may have some disadvantages when compared to a mechanical system:
* There is currently no option for manual override when the battery is exhausted. This could pose a problem for riders, depending on the type of terrain on which they are riding.<ref name = "Austen">{{cite web
| url = http://www.nytimes.com/2009/02/14/sports/cycling/14gears.html
| title = Cycling Enters the Electronic Age With a New Gear-Shifting System
| author = Ian Austen
| date = February 13, 2009
| publisher = [[The New York Times]]
| accessdate = 2010-02-12}}</ref>
* As currently implemented, each shift requires an individual button push, while many mechanical systems can move the chain multiple cogs with a single lever movement.<ref name = "Huang"/> ''N.B. The new 2013 Dura Ace Di2 9070 groupset can be programmed to multishift upon holding down the shifter buttons.'' This is now also available on Di2 Ultegra with a firmware update.
* Reliability issues have caused previous electronic systems to be withdrawn from the market. As of recently, all electronic group sets are fully waterproof. External connectors are completely waterproof, but internal connectors (internal routing) need to be shrink wrapped with shrink tubing to be waterproof. <ref name = Hagerman/>
* Cost: the system is expensive compared to lower end mechanical derailleur systems. (The Shimano Dura Ace Di2 system costs in excess of $2500 in May, 2010).<ref>{{cite web
| url = http://www.competitivecyclist.com/za/CCY?PAGE=CATEGORY_VIEW&CATEGORY.ID=2333&MODE=NONAV&gclid=CIKHk-PIxpoCFQJ2xgodqSl4rQ&gclid=CKDFyMjW96ECFQG3sgodTR6fEQ
| title = The Competitive Cyclist
| accessdate = 2010-12-22}}</ref>
* Weight: a Di2 system is heavier than the equivalent Dura Ace cable shifted system. ''N.B. the new 2013 Dura Ace Di2 9070 groupset is actually slightly lighter than the 9000 groupset
''


* There is currently no option for manual override when the battery is exhausted. This could pose a problem for riders, depending on the type of terrain on which they are riding.<ref name = "Austen">{{cite news | url = https://www.nytimes.com/2009/02/14/sports/cycling/14gears.html | title = Cycling Enters the Electronic Age With a New Gear-Shifting System | author = Ian Austen | date = February 13, 2009 | newspaper = [[The New York Times]] | accessdate = 2010-02-12}}</ref> However, SRAM's RED eTap groupset's interchangeable derailleur batteries makes it possible to manually switch batteries between the two derailleurs in order to place the battery with remaining charge onto the derailleur the user intends to shift.<ref>{{cite web | url = https://sramroadsupport.zendesk.com/hc/en-us/articles/206805888-Are-the-front-and-rear-derailleur-batteries-interchangeable | title = SRAM Road Electronic Groupset FAQ Batteries Batteries | quote = Are the front and rear derailleur batteries interchangeable? Yes. Additionally, shifters use one CR2032 coin type battery each. | publisher = [[SRAM Corporation]] | accessdate = 2015-09-12}}</ref>
== See also ==
{{transmission types}}
* [[Hub gear]] - another bicycle gear shifting system alternative
* [[List of cycling topics]]
* [[NuVinci Continuously Variable Transmission|NuVinci]] - continuously variable planetary transmission for bicycles
* [[Semi-automatic transmission]] - electronic gear shifting for automobiles and motorcycles


* Reliability issues have caused previous electronic systems to be withdrawn from the market. As of recently, all electronic group sets are fully waterproof. External connectors are completely waterproof, but internal connectors (internal routing for wired systems) need to be shrink wrapped with shrink tubing to be waterproof.<ref name="Hagerman" />
== Gallery ==
* Cost: The system is expensive compared to lower end mechanical derailleur systems. (The Shimano Dura Ace Di2 system costs in excess of $2500 in May, 2010).<ref>{{cite web | url = http://www.competitivecyclist.com/za/CCY?PAGE=CATEGORY_VIEW&CATEGORY.ID=2333&MODE=NONAV&gclid=CIKHk-PIxpoCFQJ2xgodqSl4rQ&gclid=CKDFyMjW96ECFQG3sgodTR6fEQ | title = The Competitive Cyclist | accessdate = 2010-12-22}}</ref>
<gallery>
* Weight: Electronic groupsets are typically heavier than their mechanical counterparts.<ref>{{cite web | url = https://sramroadsupport.zendesk.com/hc/en-us/articles/206576578-Is-SRAM-RED-eTap-lighter-than-your-competitor-s-electronic-groups-What-about-weight-comparisons-to-RED-mechanical | title = SRAM Road Electronic Groupset FAQ Batteries Batteries | quote = The complete SRAM RED eTap groupset is 137 grams heavier than SRAM RED mechanical with the same crankset, bottom bracket, and a short cage rear derailleur. | publisher = [[SRAM Corporation]] | accessdate = 2015-09-12}}</ref>
File:Electronic rear derailleur.jpg|Electronic rear derailleur

File:Electronic shift lever.jpg|Electronic shift lever
== See also ==
File:Electronic front derailleur (front view).jpg|Electronic front derailleur (front view)
* [[Hub gear]]
File:Deragliatore elettronico.jpg|Mavic Mektronic rear derailleur
* [[Outline of cycling]]
</gallery>
* [[NuVinci continuously variable transmission]]
* [[Semi-automatic transmission]]


== References ==
== References ==
{{Reflist}}
{{refs}}


== External links ==
== External links ==
* [http://bike.shimano.com/publish/content/global_cycle/en/us/index/products/road/di2.html#/site/product/7970/road Shimano's description of their Di2] with technical specifications and exploded views
* [https://web.archive.org/web/20100219075756/http://bike.shimano.com/publish/content/global_cycle/en/us/index/products/road/di2.html#/site/product/7970/road Shimano's description of their Di2] with technical specifications and exploded views
* [http://eps.campagnolo.com/ Campagnolo's description of their EPS] with technical specifications and exploded views
* [http://eps.campagnolo.com/ Campagnolo's description of their EPS] with technical specifications and exploded views


{{Commonscat}}
{{Gears}}
{{Gears}}
{{Bike equipment}}
{{Bike equipment}}

Latest revision as of 18:54, 15 September 2024

Electronic front derailleur (Shimano Di2)

An electronic gear-shifting system is a method of changing gears on a bicycle, which enables riders to shift with electronic switches instead of using conventional control levers and mechanical cables. The switches are connected by wire or wirelessly to a battery pack and to a small electric motor that drives the derailleur, switching the chain from cog to cog. An electronic system can switch gears faster and, because the system does not use Bowden cables and can calibrate itself, it may require less maintenance.[1]

History

[edit]
Electronic shifting control unit and battery pack mounted to the bottom of bottom bracket and left chain stay
Electronic rear derailleur (Campagnolo Record EPS)
Handlebar mounted controls

In 1990, the Japanese bike component manufacturer SunTour introduced the Browning Electronic AccuShift Transmission (SunTour BEAST) - a triple crankset/chainset system for mountain bikes in which one quarter of the circle is hinged along a radius. During shifting, this segment is pushed sideways by a relay operated mechanism like a railroad switch and picks up the chain that is currently running on the next cog.[2]

In 1992 the French manufacturer Mavic introduced their first electronically controlled gear shift mechanism called Zap at the 1992 Tour de France. It was a prototype, but it achieved neither technical success nor commercial application. A development of this was used by Chris Boardman to win the opening time trial (prologue) of the 1997 Tour de France.[3]

In 1994 Sachs introduced the Speedtronic.[4][5]

Mavic Mektronic rear derailleur

In 1999 Mavic introduced the Mektronic, its second electronic shift system, which suffered from reliability issues and was subsequently discontinued.[3]

In 2001 Shimano introduced a set of trekking components called Di2 (Digital Integrated Intelligence), which included electronic shifting and automatic adaption of front and rear derailleur to riding speed.

During the 2000s both Shimano and Campagnolo (2005)[6] experimented with electronic shifting in professional cycle races.[3]

The first commercially successful electronic gear shift system for road bicycles was introduced by Shimano in 2009, the Di2.[3] Three professional teams used the Di2 in the 2009 Tour of California: Columbia High Road, Garmin Slipstream, and Rabobank;[3] and several teams and riders, including George Hincapie, used it during the 2009 Tour de France[7]

Also in 2009 Giant released a bicycle equipped with the Shimano Di2[3][8] and Trek began providing a battery mount and Di2-specific cable routing and stops on its Madone frames.[9]

In 2015 SRAM announced its wireless electronic groupset called, SRAM RED eTap. The group was released in Spring of 2016 and is available on complete bikes and through aftermarket SRAM component dealers.[10][11]

A wireless system that can be retrofitted onto any bicycle was announced in 2016.[12] The front and rear derailleurs remain in place, while a wireless gear-change controller is added to the handlebar, with configuration of the system via an iOS/Android app, and customization can be added to the button controllers via the Bluetooth app.[13]

Implementation

[edit]
Electronic rear derailleur
Electronic shift lever

As of 2009, one system was commercially available from a major parts manufacturer: Shimano's Di2 (Dura-Ace 7970) for road bicycles. While the traditional method of gear shifting uses mechanical control levers that pull and release Bowden cables and spring-loaded derailleurs, Di2 is controlled by electronic switches located either in the integrated shift levers and/or at the end of time trial bars. The switches send signals through a wiring harness to a battery pack, placed near the bottom bracket. The rechargeable lithium-ion battery pack supplies power to the derailleur motors, which move the derailleurs via worm gears. Shimano estimates that their 7.4-volt battery pack can last up to 1,000 kilometres (620 mi) per charge.[14] The system also has an LED light to warn when it needs a charge.[15]

The rear derailleur has shift times similar to mechanical systems and a break-away system to protect it in case of a crash.[15] The front derailleur, however, switches gears almost 30% faster than Dura-Ace’s mechanical counterpart.[1] On traditional bikes, the front derailleur is problematic because the chain can be under tension and has to make a large vertical jump between chainrings. The electronic system's controlled motion overcomes these problems. The Di2 can also trim the front derailleur to eliminate chain rub and calibrate itself to adjust for wear and tear.[16] Finally, the entire 7970 groupset weighs approximately 113 grams (4.0 oz) less than the 7800 it replaces but 68 grams (2.4 oz) more than the new 7900.[17]

In 2011 Shimano introduced the Ultegra Di2[18] electronic gear change set, a cheaper version of the electronic Dura-Ace system. This set seemed to provide an electronic option within reach of a wider audience.

Campagnolo introduced their first system of electronic shifting, EPS, in the same year.[19] By 2012 Campagnolo had three electronic shifting groupsets available.[20] Cyclists began to see a growing range of electronic alternatives to traditional mechanical shifting for derailleur gears.

Wireless shifting

[edit]
Electronic front derailleur (front view)
Production SRAM RED eTap rear derailleur installed on bike (2017)
SRAM RED eTap HRD brake lever

A wireless system was announced by Tiso in 2012, but this did not achieve widespread use.[21]

In August 2015 SRAM Corporation announced its wireless shifting system, eTap.[22] The system had been extensively developed and secretly tested over several years from initial design to a stage win in the 2015 Tour de France. The front and rear derailleurs use direct-mount batteries and communicate wirelessly with the shifters through a proprietary wireless protocol developed by SRAM called, Airea (pronounced: area). A set of small satellite shifter buttons, called Blips, can be connected to the shift levers or aero shift module (BlipBox) and placed anywhere along the handlebars as part of the system. A maximum of four Blips can be used per bike. The company also took the opportunity to introduce a new shifting convention with this system. The right lever shifts the rear derailleur outboard, the left lever shifts the rear derailleur inboard, and pressing both levers together shifts the front derailleur. SRAM made the groupset available for purchase on complete bikes and as aftermarket components sold through dealers from Spring 2016. Eventually, extension of the system is expected to the company's lower group sets, such as SRAM Force. In May 2016 the company announced a hydraulic disc brake version of its wireless road group called SRAM RED eTap HRD. The new brakes make use of a hydraulic lever design with both lever reach adjustment and lever contact point adjustment, a first for road disc brakes.

Advantages and disadvantages

[edit]

An electronic system can have several advantages over a comparable mechanical system:

  • eliminate the need for the rider to switch hand positions in order to shift[1]
  • allow for an accurate and effortless shift, even in difficult circumstances, such as if the rider has cold hands or is completely exhausted
  • shifting performance is not affected by contaminated, stretched, or worn Bowden cables
  • automatic trim function can eliminate chain rub[1]
  • shifts can be timed to occur at a particular point in the cassette or chainring rotation, making best and smoothest use of ramps and cutouts in the sprocket teeth
  • the front and rear shift pattern on a bike with multiple chainrings can be programmed to make best use of the gear progression, avoid duplicate ratios and relieve the rider of the need to decide what combination of front and rear sprockets to employ
  • the smoothness of electronics can reduce the shock on drivetrain components[5]

An electronic system may have some disadvantages when compared to a mechanical system:

  • There is currently no option for manual override when the battery is exhausted. This could pose a problem for riders, depending on the type of terrain on which they are riding.[3] However, SRAM's RED eTap groupset's interchangeable derailleur batteries makes it possible to manually switch batteries between the two derailleurs in order to place the battery with remaining charge onto the derailleur the user intends to shift.[23]
  • Reliability issues have caused previous electronic systems to be withdrawn from the market. As of recently, all electronic group sets are fully waterproof. External connectors are completely waterproof, but internal connectors (internal routing for wired systems) need to be shrink wrapped with shrink tubing to be waterproof.[16]
  • Cost: The system is expensive compared to lower end mechanical derailleur systems. (The Shimano Dura Ace Di2 system costs in excess of $2500 in May, 2010).[24]
  • Weight: Electronic groupsets are typically heavier than their mechanical counterparts.[25]

See also

[edit]

References

[edit]
  1. ^ a b c d Best, Paul (2009-04-08). "Shimano's Dura-Ace Di2 electronic shifting to give road racers a time advantage". Gizmag. Retrieved 2010-02-10.
  2. ^ Michael Sweatman. "Browning". Retrieved 2012-09-10.
  3. ^ a b c d e f g Ian Austen (February 13, 2009). "Cycling Enters the Electronic Age With a New Gear-Shifting System". The New York Times. Retrieved 2010-02-12.
  4. ^ "SRAM History". Archived from the original on 2009-10-06. Retrieved 2010-02-17.
  5. ^ a b Phillips, Matt (9 Feb 2010). "The Shift to Electric". Bicycling Magazine. Archived from the original on April 17, 2009. Retrieved 2010-02-10.
  6. ^ Lennard Zinn (September 15, 2009). "Campagnolo's Magic Lives on in Vicenza". VeloNews. Retrieved 2010-02-17.
  7. ^ David Arthur (9 July 2009). "Pro riders on Shimano Dura-Ace Di2". RoadCyclingUK. Retrieved 2010-02-12.
  8. ^ "TSR Advanced SL LTD". Giant Manufacturing. Retrieved 2010-02-12.
  9. ^ "Madone 6 Series". Trek Bicycle Corporation. Retrieved 2010-02-12.
  10. ^ "When is SRAM RED eTap available? – SRAM Road Electronic Groupset FAQ". Archived from the original on 2015-09-07. Retrieved 2015-09-11.
  11. ^ "Where is SRAM RED eTap available? – SRAM Road Electronic Groupset FAQ". Archived from the original on 2015-09-19. Retrieved 2015-09-11.
  12. ^ Ben Coxworth (December 7, 2016). "The 10 best cycling innovations of 2016". New Atlas. Retrieved 2017-06-04.
  13. ^ Tyler Benedict (November 2, 2016). "X-Shifter's universal wireless shifting kit goes live". Bike Rumor. Retrieved 2017-06-04.
  14. ^ Crowe, Paul. "Electronic Shift By Wire on Bicycle". The Kneeslider. Retrieved 2010-02-09.
  15. ^ a b James Huang (Aug 2009). "Shimano Dura-Ace Di2 transmission". BikeRadar.com. Retrieved 2010-02-13.
  16. ^ a b Hagerman, Eric (2008-07-31). "Shimano Shuns Cables for Full Electronic Shifting". Wired. Retrieved 2010-02-09.
  17. ^ Cole, Matthew (2008-08-01). "Shimano unveils Dura-Ace Di2 electronic groupset". BikeRadar.com. Retrieved 2010-02-09.
  18. ^ Richard Tyler (Jun 20, 2011). "Shimano Ultegra Di2 – First look". BikeRadar.com. Retrieved 2012-09-10.
  19. ^ Stephen Farrand (Oct 25, 2010). "Campagnolo show off new electronic gear system". BikeRadar.com. Retrieved 2012-09-10.
  20. ^ Robin Wilmott (Jul 17, 2012). "Campagnolo Athena EPS 11-speed launched". BikeRadar.com. Retrieved 2012-09-10.
  21. ^ Ben Coxworth (December 18, 2012). "Tiso unveils wireless electronic gear-shifting for road bikes". GizMag. Retrieved 2015-09-12. Shift signals are transmitted from the shifters to the control unit via Bluetooth and/or another unspecified type of radio protocol – Shimano and Campagnolo's systems, by contrast, use electrical wiring.
  22. ^ Warren Rossiter (August 26, 2015). "SRAM Red eTap ushers in wireless shifting era". BikeRadar. Retrieved 2015-09-12.
  23. ^ "SRAM Road Electronic Groupset FAQ Batteries Batteries". SRAM Corporation. Retrieved 2015-09-12. Are the front and rear derailleur batteries interchangeable? Yes. Additionally, shifters use one CR2032 coin type battery each.
  24. ^ "The Competitive Cyclist". Retrieved 2010-12-22.
  25. ^ "SRAM Road Electronic Groupset FAQ Batteries Batteries". SRAM Corporation. Retrieved 2015-09-12. The complete SRAM RED eTap groupset is 137 grams heavier than SRAM RED mechanical with the same crankset, bottom bracket, and a short cage rear derailleur.
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