Bosch Performance Line CX motor sounds like a loud milk float. Is it normal?

Old Fart At Play

Pedelecer
Jun 11, 2020
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Hello there...
Thanks for adding me to the community.

I've just bought a Trek Allant+ 8 with a Bosch Performance Line CX motor. The bike is lovely, but the motor makes a really loud whine, a bit like a milk float. Particularly bad at my normal cycling cadence of about 90 rpm. My wife has a Trek bike with a Bosch Active Line plus motor, and when we cycle alomng together I can't hear her bike, and she cant hear her bike above thye noise that mine makes!
It doesn't matter which mode I am in, from eco to turbo, the noise is pretty much the same. The only time it is quiet is when I switch the motor off (or go above 15mph)

Is this noise normal? Does anyone have experience of the performance line CX motor?

Many thanks

Cheers, John
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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Back to the dealer to look at.
 

Benjahmin

Esteemed Pedelecer
Nov 10, 2014
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That sort of noise would normally indicate that the motor revs are too low, but at the cadence you state.......?
As Neal says, take it back, 'snot right.
 

Nev

Esteemed Pedelecer
May 1, 2018
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I think I would also do what the others have suggested and take it back to have it checked over. How much louder is it than the Active Line motor? The reason I ask is because I have two e-bikes one with the CX motor and one with the Active Line motor and there is a big difference in the sound produced by each motor.

Like you my cadence tends to be around the 90 rpm level, and I would say the CX motor produces more the twice the sound than the Active line motor.
 

Old Fart At Play

Pedelecer
Jun 11, 2020
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Thanks, that's really helpful. I am taking the bike back this morning, but I have a growing suspicion that the noise is normal.
I would describe the active line plus motor as a gentle hum, not particularly noticeable. But the CX motor is a sort of 'look out here I come' penetrating whine.
I'm hoping my LBS man (good guy) will be familiar enough with the different motors to be able to tell whether it is normal or not.
If it is normal, had I known how loud it is, I wouldnt have bought this bike. As it is, I guess I'll just have to get used to it.
Either way, by taking it back, at least I should know for sure!
One other thing. Your CX bike - does it make a noise when you push it backwards? A bit like the whine but very toned down? Mine does. No noise when pushing it forwards, but definite sound when pushing backwards. Weird.
 

Old Fart At Play

Pedelecer
Jun 11, 2020
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Thanks also to the other posters, appreciated - yes I am taking the bike back because it sounds wriong to me. But I had a suspicion that the noise might be 'normal', hence my post. These things are subjective of course, which makes it tricky.
Good to find a decent ebike forum. I was following a couple of ebike groups on facebook, but all the posts were about kits and de-restriction.
 

Nev

Esteemed Pedelecer
May 1, 2018
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One other thing. Your CX bike - does it make a noise when you push it backwards? A bit like the whine but very toned down? Mine does. No noise when pushing it forwards, but definite sound when pushing backwards. Weird.
I haven't noticed this so I don't think it does. I will check it out later today and let you know if it does make a noise and I just haven't been aware of it.
 

Old Fart At Play

Pedelecer
Jun 11, 2020
95
41
Hiya Nev...
Took it into LBS this morning. I mentioned thebackwards noise & he pointed out that when push forwards, pedals dont move - but when push backwards pedals do move ie drive engaged. Hence slight noise.

He is going to ride it himself before doing diagnostics
Cheers, John
 
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Old Fart At Play

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Jun 11, 2020
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Audio2 - I assume it is the 2020. I ordered it in February and it arrived a week ago. It is the 75nm one with 625 powertube battery. It is quite small!
 
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Nev

Esteemed Pedelecer
May 1, 2018
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Hiya Nev...
Took it into LBS this morning. I mentioned thebackwards noise & he pointed out that when push forwards, pedals dont move - but when push backwards pedals do move ie drive engaged. Hence slight noise.
Yes that's how I usually oil my chain. I put a bit of oil on the chain and then wheel the bike backwards then put a bit more on and then wheel it back a bit more. It doesn't really make any more noise going backwards than going forwards though at least I cant hear much difference (my hearing not as good as it used to be though). In fact mine makes more noise going forward than backwards due to the sound the free wheels system makes, a sort of ticking sound.

Let us know if the bike shop manage to find something wrong, there are always going to be the odd faulty motors out there and perhaps you are one of the unlucky ones that has ended up with one.
 

Old Fart At Play

Pedelecer
Jun 11, 2020
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Nev -
that's interesting. Also never thought of lubing chain that way, sounds good! Will post when I hear from LBS. It is a shame about the noise, because apart from that, I really love it!
 
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Old Fart At Play

Pedelecer
Jun 11, 2020
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Tartiflette - that's interesting, thanks. It will be interesting to see what happens next - nice to know that contacting Bosch direct is an option, though I can't imagine my LBS guy fobbing me off if there is a problem.
 

Nev

Esteemed Pedelecer
May 1, 2018
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Dont know what I did wrong with last image post, I'll try again!

Wow, it put the image in twice, sorry folks

View attachment 36089View attachment 36089
That's a really nice looking bike. Manufacturers and making e-bikes ever more stealthy looking. In a few more years it maybe impossible to tell if a bike is conventional or an e-bike.

Looking at the bike, what made you buy one with a CX motor? I use my CX equipped bike to go off road up mountains, but this bike I think is not intended for that. So I wonder why you didn't buy something like that above with the Active Line motor.