FAQs – Bosch
All Bosch motors are very different internally. When diagnosing or quoting for repair, it’s important for us to know exactly which motor you have. It’s very common to believe you have a Gen 3 motor when you actually have a Gen 2, Hopefully this page will help you correctly identify your motor.
Which generation is my Bosch motor?
Generation 1
Gen 1 Bosch “Classic” Line 50Nm (2011 – 2014) Mostly fitted to road bikes, but used in a few early EMTB’s such as Moustache and Haibike.
Generation 2
- Gen 2 Active Line 48Nm 2014 – 2018 Mostly fitted to road bikes. Early motors are silver, later ones were black
- Gen 2 Performance Line 50Nm for hub gear, 63Nm for derailleur 2014 – 2019 Fitted to road bikes and some early EMTB’s. Early motors were silver, later ones were black.
- Gen 2 Performance Line CX 75Nm 2017 – 2019 Mostly fitted Bosch powered EMTB’s and a few road bikes. Because this motor was fitted until 2019 and followed directly by the Bosch Gen 4 motor, it is often confused for the Gen 3 road bike motor.
Generation 3
- Gen 3 Active Line 40Nm 2018 – Still current. Road bike motor for flat city riding and long battery life.
- Gen 3 Active Line Plus 50Nm 2018 – Still current. Road bike motor for urban riding with small hills. Same motor, little more power but still better battery consumption.
- Gen 3 Performance Line (not available in CX) 65Nm 2018 – Still current. Road bike motor for touring i.e. longer higher hills. Also fitted to a few gravel bikes. (NOT FITTED TO MOUNTAIN BIKES)
NOTE The large chain wheel, not used on the Gen 2
Generation 4
- Gen 4 Performance Line CX 75Nm Mountain bike motor. Later upgraded to 85Nm 2020 – Still current
- Gen 4 Speed Line and Cargo Line motors are also available but essentially, all the motors are designed specifically around a certain job and battery consumption.
Does my Bosch 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’s already too late! The bearings have failed, the balls within the bearing will be wearing rapidly; as they wear they get smaller, this causes the seals of the bearing to be lifted from their seat’s allowing water or dirt straight into the motor! All ebike motors fail like this when the bearings are in distress, 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.
Why do the bearings fail, are they bad quality?
The bearings fitted to most Brose motors are extremely good quality and well sealed, but although a bearing is classed as “sealed” it is not waterproof! They are at best water and dust resistant. This is the same for 99% of the ebike motors on the market.
Why don’t they seal ebike motors against water and dirt?
It would be very easy to seal a motor during design stage, but seals add drag and drag equals battery consumption. It would be commercial suicide for a manufacturer to release a motor that achieved 1 mile less battery range than their competitor.
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.
