Bleeding the brakes / ABS problems

If the brake lever can be pulled through to the handlebars and the brake has little or no effect, there is usually air in the brake system. It must be bled.

As a DIY you can make yourself a cheap Universal venting set and carry out the deaeration yourself.

I have explained how this works in a Quick guide but can also be viewed in numerous videos on YouTube.

> See also here under Videos the tips from TRP.

ABS

Due to the more complex line routing of the ABS, air can persist in the system which is not so easy to remove.

Professionals use special 'brake bleeders' (vacuum pump), among other things. 1 | 2) for quick and safe venting. This option is probably too expensive for the Stromer DIY.

Service instructions

Shimano also uses the ABS module from Blubrake, but with the designation BS-AU 300. Website Various instructions are available. For example, there is a dealer operating manual 'ABS service software' which is used to carry out the basic settings and maintenance (EN | EN), as PDF here (EN | EN). To be able to work on the ABS, you need the dedicated ABS service software from blubrake and some external hardware (see system requirements p. 6). This is not an option for the DIY.

Bleeding the system is described in the last chapter of the dealer operating instructions 'Anti-lock braking system (ABS)' (EN | EN). See also chapter: BRAKES - 'ABS'

Many thanks to Ole Vogt for the tip!

DIY alternative

If you only need to bleed the brake system, you can hang the Stromer from the front wheel while bleeding. In the passive variant, leave it in a vertical position for 1-2 days. In this case, the front brake lever is actuated from time to time. The air bubbles in the system collect in the oil reservoir of the brake lever and can then be removed. Sources: speedpedelecreview.com | electricbikereview.com

Problems

If the brake lever does not function properly even after bleeding, the entire brake system must be checked for a leak. Special attention should be paid to this:

• the connections and bleed nipples on the brake callipers
• the brake line screw connections in the stem
• the oil reservoir of the brake lever
• the ABS unit in the top tube

Oil reservoirs

The oil servo in the brake lever can be a source of error, even if this is rarely the case. I am not aware of a service kit. You may be able to repair it with a liquid seal, e.g. K2 Siltecor Round cord help.

ABS from Blubrake

With Blubrake ABS, the unit in the top tube must be checked for leaks in the event of oil loss. The focus here is particularly on the screw connections.

Brake lever: (as at May 2024)

In some forums (1 | 2) that the braking force of the front brake decreases and the pressure point is soft, especially on the ST5 ABS, ST5 Pinion (delivered from Jan. 2024) and ST7. The brake lever can be pulled almost all the way to the handlebars.

In addition to air in the system, in some cases this appears to be caused by a defective brake lever. Bleeding the system does not solve the problem, the defective brake lever must be replaced.

In this context, one also reads about heavy wear of the brake pads. In extreme cases, they are said to after 600 be worn out by a few 1,000 km. With this fault pattern, it is advisable to check the resetting of the pistons. It should not look as shown here.

Links

More about bleeding Tektro/TRP brakes and more:

> Bleed the bike brake correctly - it's that easy > TEKTRO | TRP
> Replacing a bicycle brake lever - how to do it right > TEKTRO | TRP
> Tektro Service Videos (incl. brake piston service: oiling and mobilizing) > TEKTRO | TRP
> More about the Stromer ABS see also here in the chapter: BRAKES - 'ABS'