![CDX belt pulley with Shimano Spline 9 freewheel](https://www.bikespeed.de/pic/Ritzel_teethcount.jpg)
To remove the 25 km/h speed limit on an e-bike with a Pinion MGU motor, it is necessary to modify the pulley(s) in addition to the tuning due to the integrated gearbox in the motor. In the bikespeed tuning, the original gear ratio of the bike in its delivery condition must be entered for correct functionality.
The new pulley(s) then determine the new possible top speed.
Depending on whether your bike is equipped with a belt tensioner or if the size of the pulley(s) changes significantly, an additional belt with an adjusted length is necessary.
You can calculate all these values in the following steps.
On the bikes known to us with Pinion MGU motors, CDX pulleys for Shimano Spline 9 freewheel are installed.
The belts are Gates Carbon Drive with a tooth pitch of 11 mm.
If you are unsure about what is installed on your bike, ask your bike dealer or contact us with photos of your components.
For correct functionality, the original gear ratio of your pedelec in its delivery condition must be entered in the bikespeed tuning. To calculate this, enter the number of teeth on your rear wheel pulley and chainring into the following fields.
You can count the teeth or better yet, read them directly from the pulleys of your bike's belt drive system. (see photo above)
Rearwheel pulley
Chainring
Diameter:
134,7 mm
134,7 mm
By using the diameter, you can verify if the number of teeth is correct.
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