Electronic Shifting Guide
Electronic shifting differs from mechanical shifting because it uses small electric motors to shift the gears instead of metal cables. Batteries power the shifters and derailleurs, making them move the exact amount necessary, making shifts seamless. This is very different to traditional, mechanical groupsets that use the tension of a metal cable to shift gears.
Benefits of electronic shifting
Electronic shifting gives precise and accurate shifting, every time you change gears. Electronic drivetrains do without cables, giving you the peace of mind that once you setup your gears, they’re setup for good, without worrying about cables stretching that causes shifting to deteriorate.
By using a battery for power and small motors in the derailleurs to move the chain up and down the gears, electronic shifting systems allow fine tuning and adjustments, and can be programmed wirelessly, to offer customised performance to suit your riding style. Electronic drivetrains also allow for lighter and easier shifting, as there’s no friction in the system like with mechanical systems, giving smaller riders a better experience. There’s no need to worry about the weather interfering with electronic drivetrain either, as they are completely sealed from the elements.
Shimano Di2
Shimano Di2 was first debuted in their flagship road groupset, Dura Ace, and have since introduced it in a few more groupsets. Di2 offers amazingly precise shifts and a remarkable battery life, all with the same ergonomics and shifting method you’ve come to trust from Shimano, as well as spotless reliability.
Shimano’s Di2 uses wire to connect the shifters to the derailleurs, passing through a junction box that connects to a battery. The battery can be stored within the headtube, seat tube or within the frame if it is compatible.
Shimano also offers a cool technology called Syncro Shift, that uses the right shifter to control both front and rear derailleurs, changing the front derailleur automatically. Another unique feature of Di2 over the mechanical drivetrain is the option to add additional shifting buttons onto your handlebars.
Di2 is available for both road and mountain biking, which includes 5 different drivetrains: Dura Ace Di2 and Ultegra Di2 on the road side, and XTR Di2 and XT Di2 on the MTB side, and is even found on some urban bikes through the Alfine Di2 internal geared hub groupset. Shimano Di2 batteries can last up to 2000km on a single charge.
SRAM eTAP
SRAM came to the electronic shifting game with a different perspective. Why not completely do without the wired connection between shifter and derailleur? The SRAM RED® eTap groupset does just that using a wireless system, which uses a proprietary system called AIREA. It is designed to have little latency or gaps between you selecting a shift and the derailleur shifting and high reliability, making sure you’re never wanting for performance.
SRAM brings in their DoubleTap® system from their mechanical RED groupset. It uses a single arm under the brake lever to shift instead of two, like are found on Shimano and Campagnolo.
To shift into a higher gear you use the right-hand shifter, and for a lower gear, the left-hand shifter. To shift the front derailleur, you shift both left and right simultaneously. The eTap system is make to mimic sequential shifters on race cars.
Extra shifting buttons are also available SRAM’s RED eTap system gives a 1,000km range using two interchangeable batteries that are found on each derailleur. This makes SRAM eTap particularly easy to install and doesn’t require special frame features for wires.
Campagnolo
Campagnolo’s Electronic Power Shift, or EPS, is their electronic groupset system. It is found on Super Record EPS, Record EPS, and Chorus EPS, and uses wires like Shimano’s Di2 to actuate the shifts. It uses Campagnolo’s ergonomic drop shifters, with a single paddle lever near the brake lever and the second shift lever near your thumb on the side of the hoods.
The Campagnolo EPS system is similar to Shimano’s in that the wires go from the shifters, through a junction-style box and then onto a battery, before going to the derailleurs.
The battery can either be mounted to the frame, near the bottom bracket or bottom cage, or internally in the seat tube. Campagnolo EPS is completely waterproof and delivers smooth, fast shifts every time, with a single long-lasting battery, giving a range of 1,200 miles on a single charge.
Essentially all types of electronic shifting use batteries and motors in the mech's to actuate the derailleur. Shimano and Campagnolo currently use wires with a battery to connect the shifters and mechs. Sram uses true wireless tecnology with small batteries placed on both the shifter and mech.
Electronic shifting is incredibly fast and crisp. The gears change instantly at the tap of a button, while the battery life is far longer than you might expect. At the moment only the very top-end groupsets offer electronic shifting, but in time, this will be seen in more mid-range groupsets.
Electronic shifters do not use traditional metal cables to pull or release the derailleurs. They either use electronic wires or wireless technology to communicate with the derailleur and shift.
Etap is truly wireless, the batteries are located on the shifter and mech. No cables or wires at all are used meaning installation and replacement is incredibly easy and quick. Di2 does use wires and has one central battery. As Di2 does not use wireless, all of the battery power is used to shift meaning battery life can be longer with Di2.
Shimano Di2 crash mode is a failsafe more that the system uses when it detects what it thinks is a crash. In reality, this mode is rarely encountered.
Shimano Di2 uses a junction box for charging this can be at the end of the handlebar or a separate junction box usually under the stem. There are LED lights on this junction box one is the battery indicator light. Press and hold any shift button to see the battery level displayed in a solid or flash in either green or red indicating level.