In recent years, both Shimano and Campagnolo have introduced electronic gear-shifting systems for bicycles – instead of relying on steel cables, the systems wirelessly transmit signals from the user-operated shift levers to powered shifting actuators on the front and rear derailleurs. Now, a group of engineers from UK-based Cambridge Consultants are taking things a step further. They’ve developed a smartphone-based electronic automatic transmission for bikes.

Unveiled yesterday, the system is controlled by an app on a handlebar-mounted iPhone, and incorporates a stock Shimano Di2 electronic gear-shifting system. Other components include wheel rotation sensors, and a pedaling cadence sensor.

Data is transmitted by the sensors using low-power Bluetooth Smart technology, and is processed by an algorithm on the phone. It compares the rider’s current pedaling speed to their preferred cadence, then instructs the Di2 to shift up or down in order to restore or maintain that cadence. When it detects that the rotation of the wheels has slowed suddenly and significantly (indicating that the rider is stopping or slowing), it shifts to a lower gear.

A screen shot of the gear-changing iOS app

Besides simply making things easier for all riders, the system is particularly intended as a training tool for racing cyclists – by doing all their training at the best possible cadence, they will presumably develop more of a feeling for what cadence they should always maintain, regardless of what bike they’re on.

The system could conceivably also discourage the use of chain-unfriendly gear combinations (i.e: outside chainring to inside rear cog), and it could use the phone’s GPS feature to preemptively shift in anticipation of upcoming inclines or downhill slopes – something that Daimler’s Predictive Power Control system already does for transport trucks.

One criticism that has been voiced involves the possibility of multiple such systems interfering with one another’s wireless signals. Cambridge Consultants’ Tim Ensor addressed that concern. “Bluetooth Smart technology uses industry standard encryption to ensure the security of the system,” he told us. “The frequency hopping mechanism of the Bluetooth radio also ensures that many hundreds of cyclists could operate within a very small space without interference compromising the gear change.”

Additionally, users would always have the option of switching to manual (but still electronic) gear shifting.

Down the road, the developers also hope to integrate items such as heart rate monitors into the set-up, along with adding features such as anti-lock braking and kinetic energy recovery. In the meantime it exists as a functioning prototype, although Cambridge is looking for business partners that are interested in developing it commercially. There is no estimated price at this time, although the Ultegra version of the regular Shimano Di2 system sells for about US$$2,300.

View gallery - 2 images