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I bought my Trek Powerfly back in 2019 and it has been a great bike, providing some epic rides from the Alps to the flatter lands of the UK. In 2022, it needed some new crankshaft bearings replacing in the Bosch Gen’ 4 motor, so this was done via my Trek dealer. The cost of this motor work was £162 plus 2 way shipping to the repair place.
Following this motor service, the bike worked great until I did the Yorkshire Mountain Bike marathon in 2023. The weather was atrocious and we kept having to stop to clear mud out of the drive chains and the frames of the bikes. The day after, it took me 2 hours to get the bike completely clean because the mud had been compressed into every small space. I put the bike away fully cleaned and oiled, but when I pulled the bike out a couple of weeks later to ride it, the pedal cranks wouldn’t move as something had seized inside the motor. This is very common apparently when water gets in, and whilst this is disappointing, I was hit a bit harder when my local Trek dealer quoted me £600 for a new motor, and sadly, couldn’t guarantee that it wouldn’t happen again.
This issue brings me to my main rant about this Bosch motor. Why water manages to get inside the motor I really don’t know. I never power wash the bike so water can’t be forced into the motor housing, and apparently, water ingress is a very common issue with Bosch motors. Considering that cars and motorcycles have for over a century, used seals on their moving shafts that don’t let water in, or oil out, I’m amazed that a modern electric motor like this doesn’t have effective seals.
I looked at second hand motors on eBay, but the real issue was not about replacement, but actually fixing the water ingress problem. A bit of web searching realised the answer to my problem. The eBike Motor Centre (link below) have developed an upgrade to fix this issue and it includes mud protection seals and improved crankshaft seals, as well as the bearing replacement. So, finally, someone has improved what is a basic design issue in my view.
I sent the motor away and after its assessment, I paid the invoice of £225 and it arrived back quickly for me to put it back in the bike. This was easy and didn’t need any reprogramming or re-setting of the Bosch Kiox controller fortunately. The motor sounds great, doesn’t appear to have any extra drag from the uprated seals, and it works exactly as it should. I’ve used it a few times since and it’s great, and this is why I’m back in love with it.
Sadly, I think a lot of ebikes get scrapped because of motor issues as it isn’t always economical to have expensive parts like motors and batteries replaced. As the motors and bike frames evolve every year, I couldn’t fit a later motor to my bike without a lot of work. Anyway it’s fixed and thanks to the team at the eBike Motor Centre, my Trek Powerfly lives on to provide me with some more epic rides, even though that motor has cost me £400 in repairs over the last 3 years.
Incidentally, and on a slightly different subject, I’m now seeing free ebike charging at some trail centres in the UK, the most recent being one of my local ride locations at Sutton Bank in North Yorkshire. This is a great move as my Trek only has a small-ish battery, and I have to ride it economically to ensure the electric assistance lasts the distance, so stopping for a coffee’n’cake and getting a battery top-up extends my ride time.
Link to ebike Motor Centre and their Bosch Gen’ 4 upgrade page:https://www.ebikemotorcentre.com/bosch-gen-4-upgrade-service/
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Hello Guy, nice to see your new post. A bike with a dead Bosch motor could looking at.
BTW if the drivetrain is heavly coated in an arisal foam greese spray, it won’t stick as much. I did that at a race outside Spokan, Wa when Mt. Saint Hellen had dumped her contents.
Yep! Fully agree. It’s usually more wet than not here so oil is very important……and my dry protect oil rarely gets used😂
Thanks for the comment and advice👏👍🙏