Bikes have chains. Or belts. Or some kind of device linking the pedals and the rear wheel, anyway, so that the latter goes round when you turn the former. Not with Bike2, though.
What the Bike2 chaps have come up with is a bottom bracket generator that takes the power you make, adds it to some extra power from a battery and sends all that to the rear wheel. So there’s no chain, just a wire taking your input to where it’s needed.
The benefit? Well, you don’t need a chain. That means less maintenance and more freedom with design. “We’ve been working with trikes for disabled riders, where the chain routing can be a real issue”, Nils Sveje of Bike2 told us. “We’ve also been working with Danish carers, who get around by bike and don’t want to have to do too much maintenance”.
You might expect the ride feel of a system like this to be a bit vague and disconnected. The reality is anything but: if you were blindfolded you’d be hard pressed to tell the difference. It’s really impressive. The generator gives progressive resistance like you’d expect from a mechanical drive and you can adjust the ratio of leg power to battery power using a stepless twist shifter. With the other hand you can adjust the gear, again stepless. There’s an auto gearing option too that will adjust the drive to keep you at a constant cadence.
Bike2 are just making the gearbox and the control systems, partnering with existing battery and motor manufacturers; the bike we rode had a Bafang rear hub. Would it be powerful enough to get you up the steep stuff? “Well, it’s rated to 250W continuous, let’s just say that”, commented Nils. Suggesting the peak power might be a bit above that. Or a lot.
Bike2 are looking for manufacturers to partner with at the moment. It’s certainly a really interesting concept and from our limited testing it seems to work really well. Watch this space…