"Now you go over the jump and fully engage the front brake in flight." Riding technique expert Stefan Schlie must have gone mad. Landing with the brakes applied, that can't work. Or can it? We were able to test the new Bosch anti-lock braking system for e-bikes extensively - both in practice and in the EMTB test lab. And the excursion with Bosch expert Stefan Schlie makes me break out in a cold sweat. So: jump, pull the brake lever all the way, land. Within milliseconds, the ABS sensors register the slipping front wheel. The control system reacts, the front wheel stutters barely noticeably, the tyre grips. Then my bike comes to a safe stop. That's it!
The ABS has confidently and inconspicuously prevented a disaster. The entire technology, which weighs several kilos on a car, fits into a small box on an e-MTB that clamps onto the suspension fork. Impressive: The control unit weighs only 227 grams, the surcharge for new bikes with ABS is said to be in the region of 500 euros. This means that this anti-lock braking system is light, unobtrusive and cheap enough to be of interest to a broad mass of bikers for the first time. So is the triumphal march pre-programmed?
This is what you can expect in the Bosch e-bike ABS test report:
Suitable for off-road use: The 2nd generation of the Magura brake lever
For the Swabian connection Bosch-Magura, this is already the second generation of an anti-lock braking system for e-bikes. However, the predecessor was clunky and not designed for off-road use. The new generation is set to change that. The system promises real advantages even on trails. Incidentally, the bike ABS only controls the front. This keeps the technology compact, and braking at the rear is much less likely to lead to dangerous situations and crashes anyway.
The ABS brake itself is based on the familiar Magura four-piston caliper, which is also used in the MT5. To make it ABS-compatible, Magura has designed a new brake lever that works with a larger oil volume. This is necessary to ensure that the ABS functions correctly. The remaining components, from the sensors on the brake discs to the controller itself, come from Bosch. They are seamlessly integrated into the Smart system integrated. The disadvantage: ABS will not be available on the aftermarket - not even for Smart System bikes. Instead, the Bosch ABS is connected directly to the drive system ex works, draws the smallest amounts of power required for the function from the e-bike battery and can also be operated directly in the Kiox menu or via Bosch's own Flow app.
The practical test of the Bosch anti-lock braking system
We make our first attempts in a car park. On tarmac and gravel, we soon feel confident enough to fully engage the lever. The anti-lock braking system even reacts reliably and quickly to the change from grippy tarmac to loose gravel or vice versa. Thanks to the high sampling rate of the two sensors on the brake discs. The feeling of safety is already so high in the sportiest ABS mode "Trail" that we do not recommend the "Allroad" ABS mode for off-road use. It only extends the braking distance unnecessarily. And there are no scary moments in the sporty Trail mode either. Here too, you only manage to overbrake the front wheel when you deliberately hit the brakes in a tight bend on gravel. The ABS for e-bikes does not offer cornering detection.
This does not detract from the performance on the trail. Instead, the Bosch ABS does its job smoothly and enables powerful braking manoeuvres even in tricky root passages or directly after jumps - situations in which you would otherwise at best decelerate hesitantly. Incidentally, we hardly noticed any jerking or pulsing in the lever, as we know it from cars or motorbikes. How confidently the Bosch ABS acts in any off-road situation is really impressive. Especially as all of this only works with the two rotation sensors on the front and rear brake discs and a corresponding algorithm. Acceleration and tilt sensors are obviously not needed by Bosch.
However, the ABS does not allow high stoppies, but if you work from your legs, you can still turn the rear wheel in hairpin bends. What do experienced bikers have to do on E-MTBs with ABS? This is certainly one of the most exciting questions. In short: Even very good bikers benefit from the feeling of safety, especially on confusing and steep trails with changing surfaces. Why? Because braking no longer requires attention. EMTB test manager and riding technique trainer Florentin Vesenbeckh puts it this way after intensive test rides on
demanding trails: "The synapses are free, you can concentrate fully on the terrain and your body position while riding."
And the less experienced riders? After trail use, they reported that they were less afraid of braking with the front brake, especially on slippery surfaces. All test riders found it easier to adopt an active riding position with a lot of pressure on the front. Traction and control improved.
ABS for e-bikes also has disadvantages
However, the Bosch ABS also has its pitfalls - for example, if you shift your weight too far backwards on slippery surfaces. Of course, the front wheel can slip away in such manoeuvres without ABS. But the fact is that the braking distance is much longer with ABS. If you want to use the anti-lock braking system effectively, you have to learn to actively load the front wheel. In practice, this can become critical, especially in unpredictable moments of shock when the weight shifts too far to the rear.
Also noticeable: In our initial tests, the rear wheel locked up relatively often. It is probably difficult for the body to get used to fully engaging the front brake but only using the rear brake to a limited extent. Not ideal for trail etiquette. On long descents, there is also a tendency to reach too far into the lever for maximum braking force with ABS. If there is a lot of manual force, this simply fizzles out in the control system, but in the long run makes your forearms ache.
A small field test showed that a short braking distance is not the system's strong point anyway. Three bikers, from beginners to EMTB testers, tried to bring the bike to a standstill as quickly as possible from 25 km/h on loose surfaces. Despite variables such as the uneven friction coefficient on gravel, the tendency is clear: the bike stops faster without ABS. However, all test subjects also reported that they felt safer when braking hard with Bosch ABS. Evasive manoeuvres were still conceivable here, but not without. Finally, tester Alisa also dared to tackle a tricky trail thanks to ABS. Steep and with a slippery surface. New territory for the occasional biker. "I wouldn't have ridden this without ABS," she said.
Conclusion from Adrian Kaether, EMTB editor:
"The new ABS from Bosch acts with impressive aplomb. It sustainably increases control when biking - less experienced riders benefit from more riding safety, experienced riders from more riding performance. A one-finger lever for the brake itself and an even sportier ABS mode, which allows shorter braking distances, would make the technology even more attractive for experienced trail bikers. In any case, Bosch ABS is one of the most fundamental developments of recent years and makes an essential contribution to biking safety."
Hard test facts: Measurements of braking distances and hand force with ABS
How does the use of ABS change the braking distance on loose surfaces? Does the anti-lock braking system and the newly designed brake lever increase the manual force?
Braking distances¹
Can a sensitive brake finger beat the ABS? We set out with three testers for a field test on a gravel car park. Surprisingly, all of them - from the beginner (tester 1) to the EMTB test professional (tester 3) - achieved both the shortest absolute braking distance and the significantly better average (ten measurements) with switched off control system. Despite the variable friction coefficient on gravel, one thing is clear: without ABS, you are faster.
Hand force²
In order for the ABS to work, the underlying Magura MTC brake has to move more oil and therefore relies on a larger master piston. A clever deflection is designed to prevent the manual force from increasing significantly as a result. In our laboratory comparison with the MT5, it is noticeable that the MTC delivers slightly less braking power, especially with medium hand forces. On the other hand, the maximum performance during real full braking is impeccable.
¹ The braking distances were averaged over 10 measurements. The brakes were applied on gravel, so the specific friction coefficient may vary slightly from braking to braking. Tyre pressure 1.6 bar, initial speed 25 km/h, neutral riding position.
² Measured values determined on the brake test bench in the EMTB laboratory. Braking without ABS control. The horizontal axis shows the manual force, the vertical axis the braking force in Newtons.
That's what the testers say:
Adrian Kaether, EMTB editor:
"Even experienced bikers benefit from the ABS, especially in confusing passages. On a particularly steep descent, however, I was able to brake harder without ABS and repeatedly take a different line. I would switch off the ABS before such passages with little run-out."
Alisa Rathke, guest tester:
"I felt more secure off-road with the ABS. As an inexperienced biker, I benefited from this on the trails. I had the safety and the intervention of the ABS in my head and in the end I dared to tackle slippery descents that I wouldn't have ridden without ABS."
Florentin Vesenbeckh, deputy editor-in-chief of EMTB:
"When I first heard about ABS for E-MTBs, I could hardly imagine that it would ever be relevant for trail use. The first tests surprised me extremely positively. The technology has enormous potential, even for highly experienced bikers."
Interview with Claus Fleischer, CEO Bosch eBike Systems:
EMTB: Which bikers was the anti-lock braking system developed for?
Claus FleischerBased on our experience and existing expertise - over 20 years of ABS on motorbikes, four years of eBike ABS on trekking bikes - we have decided to extend eBike ABS to other user groups. In the sporty sector, from SUV mountain bikers with everyday equipment to touring riders and super sports bikers who want to crack a Strava segment.
Will the ABS also be used in races?
I can imagine that. We tested the ABS extensively with racers and professional athletes and were able to improve the performance even further. Brake later, harder, be faster for longer. That's the idea.
Will there then be even sportier ABS modes?
There is a conflict of objectives with such traction control systems: a balance needs to be struck between lateral stability and braking performance. Trail mode is clearly performance-orientated and allows very hard braking - this comes at the expense of lateral stability. But sporty bikers can master this. Nevertheless, it is conceivable that there will be even sportier modes in the future.
Thinking in the other direction: For less experienced bikers, even winding gravel descents are a problem. But ABS can't help there, in the bend, can it?
Let's get ahead of the curve: Bike hire companies in the Alps are reporting that they are replacing rear brake pads much more frequently than front ones. Apparently, too little braking is done on the front wheel. We want people to always use both brakes thanks to ABS. That alone would make a big difference for less experienced riders.
Wouldn't an anti-lock braking system on the rear wheel also be logical?
There are two arguments against this: Firstly, the main braking power comes from the front anyway. And secondly, a locking rear wheel is much easier to control.
Will ABS soon be standard on E-MTBs?
Over the last 30 years, a number of innovations have significantly changed mountain biking. Suspension forks, disc brakes, the dropper post. And now comes ABS. Precisely because it allows the biker to actively shift their position over the front wheel, it brings real advantages. Initial scepticism towards new products is not unusual, but this gives way when the benefits are recognised. We have seen this with cars and motorbikes. In the long term, ABS will make e-mountain biking safer and faster.
Adrian Kaether
Editor
