Skarper's click-on DiskDrive turns any disc-brake bike into an e-bike — iF Gold 2025

E-bikes are heavy, costly and welded to one frame, while bolt-on conversion kits permanently clutter the bike with batteries and motors. London startup Skarper wanted electric assistance without forcing riders to choose between two bicycles.

House the motor and battery in a cassette that clicks onto a special rear brake rotor, making any disc-brake bike electric in seconds — and acoustic again the next.

Skarper's DiskDrive rotor doubles as brake disc and drive gear: riders swap the rear rotor once, then clip the wireless, fully enclosed ~3 kg unit with a 250W, 50Nm motor and built-in battery onto it. Cadence and slope sensors meter assistance, giving up to 60 km per charge before the unit clicks off and the bike rides exactly as before.

Presented in 2022 as the world's first click-on, click-off drive, it won Eurobike and Red Dot honors and the iF Gold Award at the 2025 ceremony in Berlin; Skarper raised £4.5M in 2024, and by 2026 UK shops stocked demo units and rated it 4.8 on Trustpilot.

In June 2022, British startup Skarper unveiled what it called the future of e-biking: a drive unit that powers a bicycle through its rear disc brake. The rider swaps the standard rotor once for Skarper's DiskDrive rotor, then clips on a wireless, fully enclosed unit containing the motor and battery — no modification to frame or wheels — turning the bike into an e-bike in seconds and back into a normal bike whenever the unit comes off.

The idea came from Dr Alastair Darwood, an NHS doctor and medical-device inventor who had already built an emergency ventilator with Red Bull Advanced Technologies during the pandemic. Skarper's early system offered 250W, 50Nm of torque and a 202Wh battery with up to 60 km of range, and Red Bull Advanced Technologies later helped shrink and strengthen the design so it could be manufactured at scale. Six-time Olympic champion Sir Chris Hoy backed and helped develop the product, arguing that riders should never have to choose between a bike and an e-bike.

The concept collected design honors across three competitions — Eurobike, Red Dot and finally the iF Design Gold Award at the April 2025 ceremony in Berlin — and the company closed a £4.5M funding round in 2024. By 2026 the system was on sale through British bike shops such as Dave Mellor Cycles, with in-store demo units and a 4.8 'Excellent' Trustpilot rating.

It reframed the purchase: instead of a second, heavier e-bike, riders got electric help on the bike they already owned, with no permanent change and no double cost.

The brake rotor is the one part every modern bike shares, so making it the drive gear gave the unit universal compatibility without touching the frame.

Co-developing with Red Bull Advanced Technologies turned a £1,000+ accessory into credible elite engineering, and Sir Chris Hoy's endorsement carried it to cyclists.

Keeping the unit wireless, enclosed and removable preserved the acoustic bike's ride quality, so the innovation never punished owners when the power was off.

By making electric power a clip-on accessory instead of a permanent motor and battery, Skarper removed the extra cost, weight and commitment that keep people from trying e-bikes.

After the 2022 unveiling, Skarper spent years refining the DiskDrive system with Red Bull Advanced Technologies, cutting weight and increasing power while preparing volume manufacturing. It raised £4.5M from Adjuvo and others in September 2024, and collected Eurobike, Red Dot and iF Gold awards along the way. By early 2026 the system was selling through partner bike shops in Britain with test-ride programs, and the company pushed its founding ambition: to make the DiskDrive rotor standard equipment on millions of bikes, so any rider can clip on electric power on demand.