Anti-lock braking has been pitched at mountain bikes before, but always skidded wide of the mark when it came to performance compared to the best disc brakes. Will the latest system from Bosch and Magura change all that? We take it for a ride to find out.

Need to know

• Bosch and Magura join forces to offer unrivalled braking control with their latest ABS system for e-bikes
• Speed sensors on both rotors detect skidding or rear wheel lift, but only the front braking is modulated by the ABS system
• The second-generation design is 55% lighter and 77% smaller than the original
• Four modes customise the braking characteristics for Cargo, Touring, Allroad and Trail bikes
• Only available as original equipment on Bosch e-bikes

The Bosch e-bike ABS system was fitted to a Mondraker Crafty R

Shorthand for Anti-lock Braking System, ABS it’s not an acronym, it’s an initialisation, because you don’t pronounce it as a word like NASA. That doesn’t make it any less high-tech or exciting though. But what exactly is ABS?

The brains of the system is mounted to the back of the left fork leg

In short, it’s a feedback loop within the brake system that stops the wheels locking up and losing traction when braking hard. Most modern cars have it fitted as standard as it’s been shown to dramatically reduce stopping distances and increase safety. Pressure sensors on the brake lines and speed sensors on the brake rotors/wheels allow the system to know when the wheels are locked and how much hydraulic pressure is being applied. Then, with some clever mathematics and decouplers, an algorithm calculates how much the line pressure needs to be reduced to allow the rotor and ultimately the wheel to rotate slightly and generate the maximum stopping force where the rubber meets the road. This all happened repeatedly and in the blink of an eye when you slam on the brakes, unbeknownst to the driver, or in this instance, the rider.

Magura’s ABS lever is long and uses a parallel piston with large oil volume rather than the brand’s usual radial design

Now, this isn’t the first time automotive technology has been trialled on mountain bikes. I still remember riding an AWD, All Wheel Drive mountain bike and was less than impressed with the results. Unsurprisingly AWD has never seen the light of day, so is the same going to be true of ABS? Especially given that this is Bosch’s second attempt to adapt its proven motorcycle ABS technology for e-bikes.

Secondary rotor allows system to detect when the brake locks

But before I answer that question, let’s take a closer look at the latest ABS system from Bosch and Magura. It’s a dedicated e-bike product that’s only available as original equipment on Bosch powered e-bikes, not aftermarket. And that’s important, as the ABS system has to be hardwired into the power supply. The latest design is less than half the weight of the original and it’s also more compact, which in turn makes it less intrusive. All in, it adds 400g to the overall weight of the bike, which is nothing on a 25kg e-bike like the Mondraker Crafty R we have here.

Although data is harvested from the back brake, only the front brake gets ABS

Starting at the Magura brake lever there’s nothing out of the ordinary with the ABS system. In fact, the only real difference from the MT series brakes that you typically see on lots of e-bikes is that the MT C ABS levers do not use radial pistons. Instead, they are a parallel-piston design more akin to the SRAM levers that would normally come on the Mondraker Crafty R. They also have a larger brake fluid volume that’s designed specifically for the demands of the ABS system.

Note the sensors mounted to the caliper that monitor the secondary rotor

It’s at the callipers where we start to notice the subtle differences. Magura still uses one-piece forged four-piston designs, but take a closer look and you’ll notice small sensors mounted next to each brake caliper, which are hardwired into the system. There’s also a second, smaller rotor, that bolts on top of the standard brake rotor, which fits any standard 6-bolt hub. It’s the second smaller rotor that enables the sensor to accurately detect the wheel/rotor speed or any slippage. The brain of the system is mounted on the back of the left hand fork leg, and it has the front brake hose running through it. Inside the Control unit the wheel speed information is processed before automatically controlling the hydraulic line pressure to the front brake to prevent the wheel from locking up. So while both brakes are connected to the system and provide data, it’s only the front brake that has the anti-lock technology.

The Kiox dsiplay lets you select different ABS modes

And it’s not a one size fits all approach. Bosch offers four ABS modes with different characteristics: Cargo, Touring, Allroad and Trail. Trail being the performance mountain bike option. It’s all linked to the Kiox 300 display where you can switch between modes (here Allroad and Trail) and even monitor braking data. If that all sounds complicated, well, it is. But like all good technology it doesn’t interfere with the user experience, it merely enhances it.

The system takes a bit of getting used to, but it lets you concentrate on your lines and your weighting rather than brake pressure

How it rides

Now let’s get a couple of things clear right off the bat. I like to think that I reserve a healthy amount of scepticism when it comes to new fangled mountain bike technology. So I went out of my way to try and catch the ABS system off guard. I could still do nose-pivot turns as unimpressively as before, could Scandi-flick with the same favour and could easily do a stoppie on demand. So clearly you can still lock the wheels when needed.

The system still lets you endo and skid, but when traction is limited it gives the confidence to really lean on the brakes

Riding the ABS equipped Mondraker also highlighted how much more I rely on the rear brake to control the bike and my speed. So I made a conscious effort to change my braking style so I was depending much more on the front brake to modulate my speed. The conditions were bone dry and dusty, so traction wasn’t great, but with ABS I still had the confidence to use the front brake in situations where I was fearful of losing the front end. Which is a really good thing when you’re trying to modulate the speed of a hefty e-bike.

Levers are a bit big and clunky and don’t offer as much reach adjustment as we’d like

The front brake makes a slight chortling sound when the ABS is active, probably due to the pulsing nature of the drain and it sounds a bit like the wavy Avid rotors circa 2008, but nothing like a loud. I also noticed that my fingers felt more tired than normal. Possibly because I was braking way more than normal in an attempt to uncover any bugs in Bosch’s ABS machine…I failed.  The increased finger fatigue could also be chalked up to the fact that the reach adjusters didn’t allow me to run the lever blades as close to the handlebar as normal, and the fact that the feedback from the brake system is different to what I’ve spent the best part of 25 years getting tuned in to.