There are likely quite a few people who think that an electric bicycle might come in handy sometimes, but who aren’t willing to buy a whole other bike or permanently convert their existing non-electric model. Well, that’s why the Rubbee was created. It’s an electric drive unit that attaches to a regular bicycle in only a few seconds, and that comes off just as quickly.

The waterproof Rubbee clamps onto the seatpost via a quick release lever, and extends over the bike’s rear wheel. A shock absorber-like arm keeps it pressed down, so that its powered roller is able to maintain contact with the top of the tire – hence the name Rubbee. It reportedly even works on bikes with rear suspension.

The roller is made from a “special polyurethane compound mix” that is said to allow for a good grip between it and the tire, without excessively wearing away at the tire in the process.

Power comes from an integrated 14.4-volt 280-Wh battery pack, that can be fully charged from empty in two hours. Although it can be used to augment the rider’s own pedaling power, in “motor only” mode the Rubbee is able to deliver a top speed of 25 km/h (16 mph) and an average range of 25 km. It offers 800 watts of peak power, and weighs in at 6.5 kg (14 lb).

Riders control the motor’s output level via a handlebar-mounted throttle that stays attached full-time. Should they wish to ride with the Rubbee on their bike but not in use (if they run out of battery power, for instance), it can be flipped up so that its roller isn’t touching the tire.

The device’s London-based designers are currently raising production funds, on Kickstarter. The early bird pledge level of £699 is already gone, but backers can still get a Rubbee for a pledge of £799 (US$1,227), when and if they reach production. More information is available in the pitch video below.

Cyclists interested in quickly adding electric power to their traditional bike might also want to check out the $699 Ridekick – it’s a small battery-powered trailer that pushes the bike to which it's attached.

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