When initially installing the UK-designed setup, users add a wireless cadence sensor to the cranks, they strap a tab onto the non-drive-side chainstay, and they swap the bike's existing rear brake rotor for one that's specific to the system.
From there, it's just a matter of adding the main DiskDrive unit, which hangs off the tab and engages the bottom of the rotor. That unit incorporates the 202-Wh lithium battery, 250-watt motor and other electronics (including a tail light). It can reportedly be "clicked" on or off of the bicycle in just a few seconds – the other components stay on the bike full-time.
As its name implies, the DiskDrive augments the rider's pedalling power by driving the rear wheel via the brake rotor, based on cadence and road incline. It's a strategy we've seen before – sort of – in bimotal's Elevate motor module. And yes, the rotor still also stops the bike as needed, even when the drive unit isn't attached.
The Skarper company states that the DiskDrive weighs 3.3 kg (7.3 lb), has a maximum battery range of 60 km (37 mi) per 2.5-hour charge, and delivers a top motor-assisted speed of 25 km/h (16 mph) in the European version or 32 km/h (20 mph) in the North American model.
According to a report on BikeRadar, plans call for the Skarper system to be commercially available sometime next year, at a price of approximately £1,000 (US$1,217).
According to newatlas.com