Bosch Gen 4
If you are replacing your own bearings, you will find the bearings you need and their part numbers in our bearing identifier. These parts can then be found in our shop. If you need other motor parts, contact us and we are happy to help.
If you are replacing your own bearings, you will find the bearings you need and their part numbers in our bearing identifier. These parts can then be found in our shop. If you need other motor parts, contact us and we are happy to help.
- Left side crankshaft bearing part PLB 40521
- O-ring left crankshaft half part no PLB 40532
- Drive unit bearing, lower housing part no PLB 40524
- Anchor shaft needle bearing, upper housing part PLB 40526
- O-ring gear carrier part PLB 40530
- Steel transmission bearing part PLB 40528
- Bearing for right-hand crankshaft part PLB 40520
- O-ring, lower armature bearing support part PLB 40529
- Anchor support bearing left part PLB 40523
- Needle bearing for transmission shaft, lower housing part PLB 40525
- Inverter support bearing for right hand motor cover PLB 40527
- O-ring bearing shaft small part PLB 40531
- Support bearing for the motor drive gear. Part PLB 40522
Generation 4• Gen 4 Performance Line CX 75 Nm mountain bike motor. Later updated to 85 Nm in 2020 – still in the programme.• Gen 4 Speed Line and Cargo Line motors also exist, but essentially all the motors are designed specifically for a certain function and battery consumption.
Does a Bosch motor need regular servicing?
Bosch motors are not designed to be serviced, and they should only be repaired if a fault occurs. The motors are sealed and, kept dry, they run over 80,000 km without problems.
My Bosch motor sounds a little rough, should I keep riding until it stops working?
No! If you can hear your motor making extra noise while riding, it is already too late! The bearings are damaged, the balls inside the bearing wear quickly and as they wear they get smaller, which makes the bearing seals lift from the inner/outer race, letting water and dirt straight into the motor! All Ebike motors fail this way. Do not ignore changes in the noise level of your motor, as there is a limit to what can be repaired.
Why do bearings fail, are they poor quality?The bearings fitted in most Bosch motors are of very high quality and well sealed, but even though a bearing is classified as “sealed”, it is not waterproof! At best they are water and dust resistant. This applies to 99% of the Ebike motors on the market.
Why do manufacturers not seal Ebike motors against water and dirt?
Sealing the motor at the design stage would be very easy, but seals increase drag and battery consumption. Competitively, it would be bad for a manufacturer to launch a motor that achieves 2 km less range than its competitors.
My motor creaks, is it the bearings• Bearings rumble, grind intermittently or stick. They do not usually creak. Creaking is usually caused by one of the following:• Loose motor bolts. This makes the aluminium motor housing creak against the aluminium frame.• The seatpost creaks in the frame (most sounds travel along the frame and end up in the motor area).• A loose crank
• If a new cage and chainring have been fitted (Gen 3 and 4), check the chainring bolts• The pedal makes noise• The suspension linkages make noise• The rear wheel axle is loose
Can I get additional sealing for my Gen 4 motor?
There is currently no additional protection for the Gen 4 motor. but this motor already has quite good seals fitted as new. They need to be removed and re-greased from time to time, which depends on riding conditions, your cleaning habits, weather conditions etc.
Does tuning damage or wear out the parts of my Bosch motor?During servicing we have not observed that the use of a derestriction device would have caused damage to the motor.
What can cause damage or wear to my motor besides water and dust?Slightly higher wear rates have been noted in motors used at low cadence in high gears, where the motor spins relatively slowly and tries to add more power. Pedalling at a higher cadence is definitely better and more efficient for the motor. Damage can be caused by pedal strikes and collisions, but that is it! Motors are generally very durable if they are looked after.
When should I take my motor in for service?Bosch motors are not serviceable and they last thousands of kilometres when kept dry.Can I get more power out of the motor?Not at the moment.
Can I change the motor to a newer model?In some cases this would be possible, but not as easily as it sounds. Motors can vary greatly between models: size, crank type, mounting bolt size and position, connector type and position etc. All of these can change, as can compatibility with older batteries and controllers. In the end, buying a new bike is usually cheaper and easier at the moment.