ST2 Belt – various problems

In October 2020, Stromer unveiled its first S-Pedelec with a belt drive, the Stromer ST2 Belt. While the name is derived from the classic ST2 (2014-2018), much has been completely revised: different frame, larger wheels, different handling, and a completely new drivetrain.

Problems

Just a few months after its release, customers began to experience problems. The teething troubles:

1. Shifting does not work (correctly) / noise comes from the hub
2. Support is lost / Stromer switches off after hitting a bump
3. The front brake disk makes noise at a speed of approx. 40 km/h
4. Poor support; riding at 45 km/h is not possible or only possible with great effort
5. Belt slips

Stromer has now solved the problems. If your ST2 belt causes problems with the five points, the following solutions are possible.

Solutions

1. Cause: The so-called C-ring in the hub gear can become loose, which means that the gears in the hub gear no longer mesh properly. This ring holds the gears in place. [Source]
   
   Check: Check if the yellow and red markings on the rear hub match (see image below). If they do not, the gear shift must be checked by a specialist dealer. A defect is very likely.
   
   Solution: Stromer has solved the problem in cooperation with TDCM (manufacturer of the motor) and Sturmey Archer (manufacturer of the gear hub). For end users, the problem will be rectified under Stromer's warranty.
2. Cause: The battery has a little too much space in the battery compartment and can lose the connection to the battery base when driving over a bump. This causes the Stromer to switch off and have to be restarted.
   
   Solution: The Stromer dealer can fit a spacer between the battery compartment and the battery base. See also here.
3. Solution: Stromer offers a revised brake disk
4. Solutions: Go to the settings in the OMNI app:
   1. Select support mode 3 and set the sensitivity of the pedal sensor to 100 %
   2. Calibrate
      1. Calibrate standing next to the ST2 according to the instructions on the OMNI display. See pictures below.
      2. If the support does not improve after this, recalibrate, again standing next to the ST2 but now without using the pedals.
   3. Adjust the tightening torque of the rear axle. Loosen it slightly and tighten it with a torque wrench to 28 Nm.
   4. Stromer, unlike other manufacturers (e.g., Klever), had refrained from installing a so-called snubber on the rear belt pulley. This prevents the belt from slipping. It can retrofitted become.

Image for point 1

It's best to go to the dealer and refer to the „childhood illnesses.“ There may also be a warranty from Stromer outside of the standard warranty.

Calibration (point 4.2)

In contrast to the models with a chain, help is required here.

[Source]