E-bike motor cracking or grinding? Causes & repair tips

The noise usually occurs slowly: at first it's a quiet cracking noise under load, later a constant grinding that you can even feel in the pedals. The diagnosis is quickly made in forums: bearing damage. But many cyclists think that an expensive replacement motor for between €700 and €1,000 is now due.

The cause: In most cases it is not the engine itself that is defective, but rather the outer bearings of the crankshaft. Moisture gets behind the seals, especially when high-pressure cleaners or driving in mud. The grease is washed out and the bearings seize up or corrode.

The solution: A targeted revision.

  1. Diagnosis: Hold the crank arms firmly in your hand and check whether there is any lateral play. If so, the camp is knocked out.

  2. Repair: With special Bearing overhaul kits, like those we offer for Bosch Performance or Shimano STEPS, the motor can often be saved for a fraction of the cost.

  3. Prevention: After the repair, use high-quality service grease and be careful never to spray cleaner directly onto the bearing seals.

Back to the blog