ABS system for ebikes

ABS Brake System for Ebikes under study in Germany

In Europe the demand for more powerful ebikes (with motors that allow a maximum speed of 45 Km/h) is constantly growing. Speed-ebikes are becoming more popular in those countries where they’re allowed by the law. Just to name a few: Germany, The Netherlands, Switzerland. In some countries like Italy or France, the maximum speed allowed for an ebike in order to be in the same class as a regular bike (and not a moped) is 25 Km/h (although many ebikes have been altered  to reach a 45 Km/h speed).

With a more powerful motor and more speed, an ebike must have a more powerful braking system. That’s why speed-ebikes are often equipped with hydraulic disc brakes with wide rotors: this way, a stronger braking is guaranteed.
We noticed the difference when we thoroughly tested the Stromer ST2, a high-range Swiss speed-ebike.

The results are that today even less experienced cyclists can have bikes with powerful braking systems. 
Until not so long ago this kind of braking system was only available on downhill mountain bikes, which were designed for experienced cyclists that wanted to go downhill at a very high speed. Today, everyone can walk into a shop and buy a speed-ebike for an urban use (if you have that kind of money to spend on an ebike).
In our opinion, more people should be aware that to ride such ebikes you need a proper training: speed-ebikes are very different from “regular” bikes.
Zipping through cars at a 45 Km/h speed on a 28kg bike is not a walk in the park. It’s vital that you know how to deal with emergencies like sudden stops.

A sudden stop can be far more dangerous at a medium-low speed than at a medium-high speed because in the first case the chances of locking the front wheel are higher. It’s exactly when the speed goes down to 15-20Km/h that a stop can cause the locking of the front wheel if an inexperienced cyclist pulls the brakes too hard in an emergency brake.
That’s when the braking system comes into play: a “regular” electric bike has V-brakes, or just simple mechanical disc brakes, designed to work at a relatively low speed: even if you pull the brakes hard, it’s  not likely that you’ll lock the front wheel (the worst that can happen is that your back wheel will get locked, but that’s far less dangerous).
A speed-ebike has hydraulic disc brakes with 180 or 200 mm rotors that are designed to slow the bike down at a 45 km/h speed: if you get scared and pull the brakes hard at a 15 km/h speed, it’s likely that the front wheel will stop, and you end up over the handlebars.

(Please allow us a personal note: that’s exactly how we personally saw a friend of ours fall from her bike a few weeks ago and hitting the asphalt with her head – fortunately she walked out of the accident relatively unscathed, but it could have been much worse.)

This is why a team of researchers of Pforzheim university are developing an ABS (Anti-Blocking System) for ebikes.
The project was subsidised  by the German federal government within the “Bikesafe” programme.
Researchers have collected a huge amount of info regarding the causes of the locking of the front wheel: a test bike has been equipped with several sensors  (some tests have also been done on a virtual bike).
In order to avoid any risk, they used a dummy instead of a “real” cyclist, just like in cars crash tests. They made some changes to the motor so that it could start even when the pedals are still (creating a “pedaling dummy” would have been too expensive). When the bike reached a certain speed the motor was automatically deactivated and the brakes were pulled (automatically as well). They tested different ways of braking to observe the results and to understand when and how the wheel would lock and the dummy would be thrown over the handlebars.

The second phase will be the developing of an anti-blocking system, in collaboration with some companies like Bosch and Magura. Ebikes are already equipped with a control unit and a battery that can be used to manage the ABS system too, so the extra weight of more components can be reduced.
There are other problems to solve though. First and foremost, there’s the functioning from a  technical point of view. There’s also the aesthetic side, along with the volume and the weight of such a system: the ABS shouldn’t make these aspects of the ebike worse.
Last but not least, there’s the price issue: the final price of an ebike equipped with an ABS shouldn’t be a lot more than the bikes on the market at the moment.

The researchers are currently working on the system, and we’re not allowed to know more details about the project. To know more, you can check this report from the Pforzheim university (it’s a pdf file and it’s in German) from which we have borrowed the images you see in this post.

All in all, we think that electric bikes are safer than regular bikes, for at least 5 reasons.

ABS Brake System for Ebikes under study in Germany last modified: 2015-06-22T09:07:53+00:00 by Elisa

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