Electronic bicycle derailleur
The electronic bicycle derailleur system comprises electronically controlled and electromechanically moved gearshift components on the bicycle. A bus system are derailleur and front derailleur electronically controlled and their parallelogram electromechanically actuated.
background
In cycling , the moving parts of the mechanics are constantly being improved and made lighter. With more and more gears and thus narrower sprockets and chains, the gear lever and rear derailleur mechanics became more and more demanding and precise. The aim of the development is also to enable the fastest possible "up" and "down" shifting across several gears, even under load.
| Mechanical switching unit | Electronic switching unit |
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development
Electronically controlled and operated transmissions were initially developed for racing bikes , but are now available for all types of bikes . The electronic systems are one and a half to two times more expensive than the manufacturers' analog mechanical groups.
Manufacturers have been experimenting with electronic systems since the late 1990s. In 2004, “functional parts were spotted” for the first time in professional racing cycling ( Tour ). From the mid-2010s, electronic switching units also found their way into semi-professional racing. In addition to road cycling, amateurs also use the technology in cyclocross .
Shimano
In 2009 Shimano presented electronic components for the first time under the name DuraAce Di2 (Digital Integrated Intelligence). The bike computer , a sensor in the crank arm and the rear derailleur or front derailleur communicate with each other via a dedicated bus system in the shift / brake lever ("flight deck") . The Ultegra group was later offered as a Di2 variant.
In 2014, the electronic gearshift followed with the XTR Di2 for mountain bikes . Shimano involved MTB professional Julien Absalon in the development. The group is based on the mechanical XTR group M9000 / M9020. The XTRDi2 gearshift can be operated with just one shift lever; a second shift lever can optionally be used. There are 1-way, 2-way and 3-way versions of cranks to enable the right gear ratio for cross-country, tour / all-mountain, enduro etc.
Newer bike computers from Garmin offer an integration for Di2. The computers can display gear indicators or the fields for gear ratio, chainring-sprocket combination and the battery status.
Campagnolo
Campagnolo initially installed electronic components in its leading group, Super Record . The group below in the Campagnolo ranking followed later as Record EPS . The Record 11 EPS (Electronic Power Shift) was designed in such a way that shifting can be programmed using several gear ratios in one shift step. The system consists of the electronic Ergopower levers, the motor-driven rear derailleur and front derailleur, a small interface in the driver's field of vision and the battery pack (“Power Unit” with monitoring and display function) on the down tube. Campagnolo uses cables with five-pin plugs.
SRAM
The American competitor SRAM has been working on an alternative to Di2 from Shimano and EPS from Campagnolo since summer 2013 . For Euro Bike 2015 finally put the SRAM, in its top tier SRAM Red integrated system before. SRAM Red eTap surprised many observers because it was the first wireless shifting system in bicycle technology. SRAM developed its own Bluetooth transmission protocol "Airea" for his group. The rear derailleur and front derailleur each have their own battery (the same on both switching units) and batteries are integrated in the levers (button cells of type CR2032 ). The manufacturer specifies a service life of up to 2 years. In addition, so-called “satellite switches” can be installed on the handle, which are connected by cable to the respective brake lever and follow the same switching logic.
Newer bike computers from Garmin offer an integration for SRAM Red eTap. The computers can control gear displays or the fields for transmission, chainring / sprocket combination and others.
technology
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The electronic circuit is based on electronically controlled and switching units with digital transmission, which control the electromechanically moved derailleur units. In the individual systems, the components are linked to a cycle computer, which takes over the other computing power. Sometimes there are sensors on the crank that measure the force exerted by the pedal. The data obtained in this way are also used in the calculations.
Gear lever
The shift levers look like mechanical shift-brake levers; In the brake recess, however, there are buttons with which the gears can be selected. Some of the key combinations are programmable; Campagnolo calls the function "Multishift", which can be used to shift over several gears. The signals are transmitted to the other components via a bus . The individual manufacturers developed specific bus systems for their groups.
Rear derailleur and front derailleur
The rear derailleur and front derailleur are technically constructed from the same parts. A built-in microprocessor controls a digital-to-analog converter that feeds a servo motor . The servo motor moves the parallelogram of the rear derailleur. Campagnolo uses a rod-shaped linear motor in its EPS system .
Bike computer or interface
With the change from mechanical speedometers to digital counters, the term “bicycle computer” was established for the device with which the distance covered and speed are displayed. Shimano was the first manufacturer to establish an electronic connection between its shift / brake levers (STI) and special bike computers. With this system called Flight Deck , the current gear was displayed on the bike computer. In the case of electronic drive systems, the bike computer takes on various computing tasks. Automated, sensor-controlled switching processes are thus possible.
Battery pack
The controls and motors require a relatively large amount of electricity. That is why the systems work with accumulator batteries mounted separately on the down tube. The Campagnolo EPS system works with an operating voltage of 12 V.
Individual evidence
- ↑ a b TOUR magazine: Test: Circuit Campagnolo Super Record EPS - Test Center. In: TOUR-MAGAZIN.de. Retrieved January 14, 2017 .
- ↑ BIKE magazine: Shimano XTR Di2 - electrical circuit for bikers - components. In: BIKE-MAGAZIN.de. Retrieved January 8, 2017 .
- ↑ Shimano XTR Di2 (M9050): first electronic MTB groupset . In: MOUNTAINBIKE . ( mountainbike-magazin.de [accessed on January 16, 2017]). Shimano XTR Di2 (M9050): first electronic MTB groupset ( Memento from January 16, 2017 in the Internet Archive )
- ↑ The future is wireless | SRAM Red eTap - the wireless group - Roadcycling DE . In: Roadcycling DE . ( https://roadcycling.de/rennrad-ausruestung/verbindungen-und-zubehoer/sram-red-etap-kabellose-gruppe#52tdAAsGxfMYlKVH . 97 [accessed on January 15, 2017]).
- ↑ Test: Sram Red eTap - wonderfully wireless switching. In: velomotion.de. Retrieved January 8, 2017 .