Anti-lock braking for e-bikes is a thing! and not only is it a thing, it’s a thing that works. We’ve been down to the test track to try out the new Bosch ABS system that now forms part of their e-bike system, and we’re pretty impressed.
Bosch have been making ABS systems for decades, for cars and motorbikes. The e-bike ABS is a development based on their motorbike system. There are a few bits to the system, so let’s have a look at them.
Firstly, you need to know what the wheels are doing. These disc brakes look like double discs, but that inside track is actually a timing ring. It allows the system to work out what’s happening at both ends of the bike.
The Magura disc brakes have been altered to include space for the timing sensor.
The clever stuff happens in here. The ABS system monitors the wheels 200 times a second, apparently, which is a good deal more than you could manage with your eyes and brain. It’s looking for two things: rear wheel lift and front wheel lock-up. Only the front brake is controlled by the ABS, with Bosch reasoning that the two things you really don’t want to do on an e-bike are go over the bars or lock up the front wheel on loose surfaces. Only front brake control is needed to mitigate against those situations, and that makes the system a lot simpler. The front box is able to modulate the brake pressure to keep you upright.
We’ve tried it out. And it really works, really well. Bosch’s test track is a simple tarmac out-and-back with one section covered in loose stone chippings, the kind of thing you might find on any UK road after it’s been resealed. Riding the bike at full speed and hauling on the front anchor on the grippy tarmac shows that the Magura brake is plenty powerful. When you ride onto the chippings and grab a handful of front brake, you’d expect the front wheel to lock up completely and slide out from underneath you. But no: you just carry calmly on, slowing down a bit more gently than on a decent surface. and then once the gravel is finished the brake bites again and brings you to a stop. Pretty much as you’d expect.
It’s not really a surprise that it works, given how careful Bosch are at bringing things to market, and how much experience they have in the sphere of ABS. But it’s amazing to try it in the flesh and realise what a difference it makes to control when you’re braking on poor surfaces. It won’t necessarily help you if you’re trying to brake in a turn and sliding out sideways, but if you keep your braking in a straight line it really does the job.
It’s mostly destined for city bikes at the moment if you look at the tone of Bosch’s marketing material, but there’s no reason why the system couldn’t be applied to e-MTBs too. Bosch told us that the impact on the battery life of the system is minimal, with the wheel sensors using a very small amount of power and the ABS unit itself only kicking in very occasionally in the course of normal riding.