Skarper snap-on e-bike conversion kit drives brake rotor

Quickly convert a bike into an ebike

Make cycling a lot more efficient by converting your bike into an e-bike with Skarper electric bike conversion kit. Unlike some conversion kits, there's no need to swap your bike wheel to a motorized one.

However you do need to strap on a tab on the chainstay and swap your bike's existing brake rotor with one made for the Skarper. Initial installation may be a hassle but once you have the tab and brake rotor installed it's easy to reinstall later. There's also the wireless cadence sensor you need to install on the cranks.


  • Easy clip-on installation
  • Not affected by friction
  • Smooth and powerful ride
  • Wireless
  • Disc-brake works for braking even without theDiskDrive


  • Non-removable battery
  • Smartphone app not yet available as or writing

Disc-brake rotor driven

When installed the Skarper assists the rider's pedalling by driving the rear wheel brake rotor. This seems like a more reliable way of driving the wheel than how it is done by Rubbee i.e. by putting a driver that rolls against the top of the rear tyre by friction.

Skarper's power delivery is not affected by friction like the Rubbee. Inside the Skarper drive unit are gears that connect to the disc-brake rotor of the bike and so it is not affected by friction. This drive unit is called the DiskDrive. The rotor still works for braking whether the DiskDrive is attached or not.

Skarper performance

The Skarper DiskDrive itself weighs 6.6 lbs (3 kg) and delivers a top speed of 16 mph (25 km/h) with the European version and 20 mph (32 km/h) in the American version with a torque of up to 50Nm. It has a built-in 202-Wh battery that provides up to 37 miles (60 km) of range. Charging the battery for 30 minutes can provide a range of up to 20 km.

Power delivered by the Skarper is said to be smooth and predictable thanks to the use of sensors and control algorithm that respond to your input and the terrain. Riders are provided with progressively increasing power from standstill so it feels natural. A smartphone app is in the works to allow the user to tune the system and update the firmware.

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