ABS

The ABS used by Stromer comes from the Italian manufacturer Blubrake. It was first offered on the ST5 model from 2021 and was the first in the S-pedelec category in the industry. It is based on electronic sensor technology, an encoder disk on the front wheel and an acceleration sensor IMU (Inertial Measurement Unit). This sensor measures the riding dynamics of the entire bike - i.e. the actual speed, inclination, acceleration and deceleration. It serves as a reference and recognizes when the rear wheel lifts off during heavy braking and an OTB (over the bar) is imminent.

The actual braking force control is hydraulic. Without power (e.g. empty battery), the wheel continues to brake normally, but without ABS support.

There is one restriction: the ABS does not intervene below a speed of 5 km/h, but an OTB is also almost impossible. In addition, the ABS system only affects the front wheel. If you apply the rear brake too hard, you can still expect the rear wheel to lock up.

Where is the ABS installed?

The ABS installed in the Stromer models is built into the top tube. Retrofitting to non-ABS models is not possible due to the larger space requirement.

The operating modes

The Blubrake Gen. 2, available since 2021, has four predefined profiles: Safety, Standard, Performance, Extreme and Off. When activated, there is no feedback, such as pulsation of the brake lever. The braking force increases in sequence with each profile, while the intervention of the ABS decreases. 

1. safety mode: In safety mode, the braking force is reduced. This increases the braking distance enormously, so that there is a risk of being carried out of the bend even with an unlocked front wheel because the system does not provide enough braking force.

2. standard mode: Standard mode is well suited to e-bike beginners who often ride on gravel or poorly surfaced roads. The ABS reduces the braking force to such an extent that the front wheel does not lock up on dry and wet roads (on level ground). However, a practiced index finger of a fully concentrated rider still delivers the better performance.

3. performance mode: On loose surfaces, the system only intervenes when you have already taken pressure off the brake lever. If you pull the brake lever fully, you can provoke a short-term lock-up, then the system opens and gives you back control of the front wheel with plenty of braking power and short braking distances.

4. extreme mode: According to Blubrake, the mode is suitable for riders who want to shift the rear wheel through tight hairpin bends, for example... The latter two profiles are not suitable for trekking or commuting.

For more practice details see also 'More info' below.

Which mode does Stromer use?

According to a request from the stromerforum.ch users ‚olfener' the following from Stormer:

Thank you for your inquiry and patience. The Blubrake ABS Gen. 2 is installed on the ST3 Pinion. Stromer uses the so-called standard configuration or standard mode of the ABS. The mode cannot be changed. In our opinion, this mode offers the best balance of performance and safety. However, the ST5 could perhaps also be set to the performance profile.

Can the ABS be deactivated?

This is only possible with a trick and the question remains why you should do this!

You can loosen the lower screw of the front brake calliper slightly and move the wheel speed sensor. The ABS sensor bracket on the brake calliper is marked "1 mm Distance" (to the ABS sensor disk on the brake disk). If you push the sensor outwards (and tighten the screw again), the ABS can no longer measure the wheel movement. The ABS symbol in the display lights up yellow permanently and the ABS is out of function (Source).

The disadvantage of this method is that the service symbol, a warning message or an FW upgrade may no longer be displayed because the ABS signal is permanently lit.

Problems

> See BREMSEN - 'Bleeding the brakes / problems with the ABS'

More info

> The Blubrake ABS G2 anti-lock braking system in the test
> Practical test: ABS for bikes | Bosch anti-lock braking system really good?