London-based startup Skarper has created a device that will transform your bike into an ebike


Skarper, which can hit a top speed of 32 km/hr, is slated to debut next year and is expected to retail for around £1,000

You probably didn’t think that you got a two-for-one deal when you bought the bike that you have now. But you did, and it’s thanks to Skarper.

The London-based startup helmed by Alastair Darwood has invented a device that can turn almost any conventional bike into an ebike – as long as the bike to be transformed already has a disc brake.

The Skarper kit comprises two components: a disc brake rotor it calls the DiskDrive, and a motor drive unit that clips onto the bike frame. The latter houses a battery and a 250-watt-hour motor. When installed, the DiskDrive slots into the motor drive unit. The two components engage, and the motor drive unit turns the DiskDrive’s rotor, which in turn, spins the bike’s rear wheel.

At full charge, Skarper gives a range of approximately 60km, provided that the cyclist keeps just below the legal speed limit for bikes, which is 25 km/hr in the UK and about 29 km/hr in the US. At top speed, the kit can hit 32 km/hr.

To recharge the battery, which takes only 2.5 hours, simply unclip the motor drive unit and take it home, or to the office with you. This detachable design is a major selling point for the invention, as it addresses a major annoyance for ebike users everywhere: lugging a heavy ebike upstairs and indoors every time it needs to be charged.

No more lugging a heavy ebike up the stairs; the motor drive unit can be detached when it needs to be recharged

The idea for Skarper came to Darwood in 2020 when he was in the market for an ebike. He quickly realised that good ebikes cost a lot of money, and that most conversion kits require dramatic alterations to the original bike, such as the swapping out of the wheels for powered wheels or the addition of a hub motor. Disappointed in the offerings available, Darwood decided to find his own, less invasive, conversion solution.

With Skarper, converting a bike to an ebike requires only replacing the rear disc brake rotor with the start-up’s DiskDrive – no wheel replacing or cable running is necessary. The entire kit does add 3.3 kg to the bike, but unless you are a Tour de France participant, the extra weight shouldn’t make a huge difference to your cycling experience

The device is turned on by pressing a single button

Speaking of the average rider on the road who needs a little help, Skarper is created with the DynamicClimb feature to deliver the most powerful ride in the most energy efficient way possible. The technology uses sensors and a bespoke algorithm to measure the rider’s output, road incline, and the motor drive unit parameters thousands of times a second.

To start up the kit, simply press the singular button on it, and wait for the status light to come on to indicate that the bike is ready to go. Without the motor drive unit clipped on, the bike would function like any conventional bike.

Skarper is slated to debut next year and is expected to retail at around £1,000. The device has already received a seal of approval from Chris Hoy. The six-time Olympic champion and 11-time world champion cyclist is an investor in the start-up and has been active in the device’s development.

Robb Tip: If you’re interested in folding bikes, we’ve got some suggestions for you.