Motor FAQ’s


Motors in general

My motor is creaking, is it the bearings? 

Bearings do not usually creak. When people bring their bikes to us with these noises, here are all the reasons we have found for motors, of all types, creaking or cracking, so far:
Motor bolts loose, (causes motor to creak against the frame), chainring to spider bolts lose, crank arms lose, pedal creak, seat post creaking, rear suspension linkages creaking, front sprocket loose (normally wrong type of sprocket fitted to Bosch or worn spider carriers for Yamaha). Loose spokes in the rear wheel or rear wheel spindle creaking. (when we say loose, this does not mean undone, but not tight enough to stop creaking)

Is my motor waterproof?

The answer is, probably not. Currently, it would be commercial suicide for ebike motor manufacturers to properly seal a motor  because this would lead to added friction and lower battery range. This does not look good on comparison charts when people are deciding what bike to buy.
Most road bikes don’t require seals and mountain bikes make up about 10% of the market. Get the picture. Most current bike motors rely on the bearings dust seals rather than any dedicated water seal. This situation is good enough for most road bikes but bikes used off road will struggle.

How can I protect my motor from water ingress?

There are aftermarket products for some motors, but not all. There are also some simple steps that can help: Wash your bike upright, not on its side. Store your bike upright, in a dry area. If you transport your bike behind a vehicle, ensure the motor is covered if the roads are wet. Do not direct a water hose at the motor, especially the crankshaft area. Never pressure was your bike (it’s not a motorbike, none of the motor bearings, wheel bearings or frame bearings have protective seals in front of them).
Do not ford any water deeper than the bottom of the motor.

If water gets into my motor, will it dry out?

Yamaha do have a small breathable membrane that allows the motor to dry out over a very long period of time. If the water is more than a drip, the motor will be in trouble. Most other motors do not have this small membrane and once water is inside, it cannot escape. (motors are definitely not designed to have moisture of any kind inside them).

My crank is sometimes seized when I push my bike out the garage?

This is because water has entered a bearing during washing or your last ride. Water will rust the balls of the bearing to the bearing race. This generally signifies the beginning of the end for the bearing.

Is it ok to put some oil on the bearings or down the crankshaft?

No! If you feel you have to put oil on bearings there is already something wrong that requires attention. Also, these motors are not designed to have oil inside them. It can cause issues with clutch bearings, circuit boards, coatings and lubricants. Above all it makes a horrendous mess that we normally have to clean out! Even just a couple of drops every now and again will build up over time.

Does riding in turbo/power mode cause extra wear or damage to the motor?

Turbo or power mode is adding slightly more power through the drive train and therefore will possibly wear the motor out maybe a few miles faster than some of the lower power levels, but to be honest, we have not witnessed any difference in any motor used extensively on full power to any other motor used predominantly in low power. We have not yet seen a motor worn out or failed because it was used in its higher power levels.

Do tuning dongles or chips cause any damage?

We have never seen any damage to a motor caused by the use of a de-restricting device.

What can cause damage or wear to a motor apart from water and dust?

We see slightly higher wear rates in motors used with low cadence in high gears, so the motor is spinning relatively slow but trying to add full power. Pedaling at higher cadence (rpm) is definitely better and more efficient for the motor.
Damage can be caused by pedal strikes and crashing, but that’s about it! Motors are generally very resilient if looked after.


Can I re-grease the bearings?

The bearings in all ebike motors are already greased and should be good for the life of the motor. If a bearing has been damaged by water or dirt ingress, it will be permanently damaged and no amount of special grease will help. You will just make the inevitable quieter.

Why are ebike bearings so bad?

Ebike bearings are often high quality, over engineered bearings. Way bigger and stronger than they need to be. The bearings are not to blame, it’s normally more to do with the environment that the bearings have to deal with.

What if I just keep riding, noisy bearings last for ages don’t they.

Not with an ebike motor ridden in harsh conditions or washed regularly they don’t. Lets look at a crankshaft bearing for example: As the bearing wears the ball bearings within it become smaller, this allows movement of the bearing and can usually be felt as play in the crankshaft. This “play” lifts the bearing seals from their seats and this allows water and dirt to enter the bearing, speeding up the total failure. If you can hear the bearings whilst riding, it is already too late!

FAQ Bosch

Which generation is my Bosch motor?

 Gen 1 (2011 – 2014)
All Bosch motors are very different internally. When diagnosing or quoting for repair, it is important for us to know exactly which motor you have. It is very common to believe you have a Gen 3 motor when you actually have a Gen 2.
Gen 1 Bosch “Classic” Line 50Nm (Mostly fitted to road bikes)

Gen 2 Active Line 48Nm (Mostly fitted to road bikes 2014 – 2018)
Gen 2 Performance Line 50Nm for hub gear, 63Nm for derailleur (fitted to road bikes and some early EMTB’s 2014 – 2018)
Gen 2 Performance Line CX 75Nm Fitted to all Bosch powered EMTB’s from (2014 to 2019)Gen 3 Active Line 40Nm Road bike motor for flat city riding and long battery life (Same motor, just fed less power 2018 – )
Gen 3 Active Line Plus 50Nm Road bike motor for urban riding with small hills (Same motor, little more power but still better battery consumption. 2018 – still current)
Gen 3 Performance Line (not available in CX) 65Nm Road bike motor for touring i.e. longer higher hills. Also fitted to a few gravel bikes. (NOT FITTED TO MOUNTAIN BIKES) (2018 – still current)
Gen 4 (2020 – still current)
Performance Line CX 85Nm Mountain bike motor
Speed Line and Cargo Line motors are also available but essentially, all the motors are designed specifically around a certain job and battery consumption seems to be the key.

Does my motor require regular service?

Bosch motors are not designed to be serviced and should only fixed if they start to fail. The motors are sealed for life and if kept dry will do in excess of 50,000 miles (80,000km) without problem.

My motor sounds a bit rough, should I just keep riding it until it stops?

No! If you can hear your motor is noisy while riding, it is already too late! The bearings have failed, the balls within the bearing will be wearing rapidly and as they wear away they get smaller, this causes the seals of the bearing to be lifted from their seat and allows water or dirt straight into the motor! All ebike motors fail like this, and it’s a cascading effect. Don’t ignore any change in noise level from your motor, there are limits to what can be repaired.

My motor is creaking, are the bearings failing?

Normally. Bearings tend to rumble, grind, crank and crunch intermittently or seize. They don’t creak. Creaking is usual caused by one of the following:
Loose motor bolts. This causes the aluminium motor body to creak against the aluminium frame.
Seat post creaking in the frame (most noises travel down the frame and emanate from the motor area).
Crank arm loose
If spider and chainring fitted, (Gen 3 and 4) check chainring bolts
Pedal creaking
If fitted, suspension linkage creaking
Rear wheel axle loose

Can I get any extra seals for my Gen 4 motor?

There is currently no extra protection for the Gen 4 motor. but there are already some pretty good seals on this motor. They do need removing and re-greasing from time to time and this will depend on your riding terrain, cleaning habits, weather conditions etc.

FAQ Brose

Does my motor need regular service?

Brose motor should have its drive belt changed after 9,300 miles (15,000km). The rest of the motor is not designed to be serviced and should only fixed if it starts to fail.

Motor works on walk assist but will not work when I pedal?

This is usually caused by failure of the torque sensor and should be sent to us for torque sensor replacement.

My crank is stiff to turn backwards

This is normally the first sign that your motor crankshaft needle roller bearing is failing due to rust or a build-up of dust or grit.

My motor makes cracking, popping or screeching sounds

A fairly sure sign that one of the two motor clutch bearings are failing. Definitely worth getting this investigated as it will result in complete loss of drive.

My motor runs on when I stop pedalling

This can be one of two reasons:
1, the crankshaft needle roller bearing is badly seized, breaking up or contaminated. This causes the crankshaft and sprocket carrier (torque sensor) to become one or very stiff to turn independently of each other.
2, the clutch bearing is starting to fail and the ‘sprags’ (small feet that lock the bearing) are beginning to jam or stick. Both these scenarios allow the motor to continue to add power because it can only see that the crankshaft is still turning. This may happen right up to the cutoff speed.

FAQ Impulse

Does my motor need regular service?

No, these motors are not designed for regular servicing. However, one of the main causes of failure for this motor is the grease used for lubricating the steel gears and freewheel pawls. There are several major issues caused by this and the sooner this grease is removed and changed for a lighter grease the better.

Can you fix the Kalkhof clack?

Yes, we have identified the issue and  it’s fixable.

My motor seems to be getting louder?

This is quite usual for this motor and it should be addressed as soon as possible.

FAQ Yamaha

My motor seems to be getting nosier over time?

Yamaha tend to use a grease that dries out or disperses over time. After approx 1,500 miles they could normally do with a cleanout and refresh. This quietens them down quite a bit. Obviously if bearings are beginning to fail, this will also increase noise.
My motor seems noisy compared to others?
The later Yamaha motors seem a little worse for this and we have found poor or damaged internal bearings on relatively new motors. Gear damage is also relatively common.