Bosch cx motor bearings after only 570 mile ??

Kbanny

New Member
Sep 27, 2018
14
9
Barnoldswick (LANCS)
Hi my cube stereo has the bosch cx motor ive had it 2 month and the bearings are sounding ruff already i even had to force the crank this morning as it almost locked up. I've only done 570 mile and only 2 month in to the warranty this does not fill me with much confidence thinking im going to be back every 2 month with the same problem. Any advice with this problem appreciated!!
 

Bearing Man

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Sep 29, 2018
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Hi my cube stereo has the bosch cx motor ive had it 2 month and the bearings are sounding ruff already i even had to force the crank this morning as it almost locked up. I've only done 570 mile and only 2 month in to the warranty this does not fill me with much confidence thinking im going to be back every 2 month with the same problem. Any advice with this problem appreciated!!
Hi Kbanny,
The reason you had to force the crank is because enough water has got into the bearings to rust the balls to the bearing races. This sadly is the beginning of the end. Once rust has developed in the bearing it will slowly destroy itself.
The real issue is, how did so much water get in there in the first place? Is their any silicone grease behind the bearing seal? Was the bike jet washed or enthusiastically hosed around the chainwheel area? Was the bike laying on its left side at any point during the wash, did you stop in the middle of a deep stream etc, etc.
The thing is, the damage is done. If it is making a noticeable noise, I would take it back to the dealer and see if you can get it changed under warranty. Pssst, if you did jet wash it, keep quiet! :censored:
If you need to ask any further questions Kbanny, feel free.
Pete.
 

Kbanny

New Member
Sep 27, 2018
14
9
Barnoldswick (LANCS)
Maybe @Bearing Man can offer some insight
Yeah if i
Hi Kbanny,
The reason you had to force the crank is because enough water has got into the bearings to rust the balls to the bearing races. This sadly is the beginning of the end. Once rust has developed in the bearing it will slowly destroy itself.
The real issue is, how did so much water get in there in the first place? Is their any silicone grease behind the bearing seal? Was the bike jet washed or enthusiastically hosed around the chainwheel area? Was the bike laying on its left side at any point during the wash, did you stop in the middle of a deep stream etc, etc.
The thing is, the damage is done. If it is making a noticeable noise, I would take it back to the dealer and see if you can get it changed under warranty. Pssst, if you did jet wash it, keep quiet! :censored:
If you need to ask any further questions Kbanny, feel free.
Pete.
Hi I've never used a power washer on the bike and only very briefly wash with hose in the crank area also the crank area has never been under water only through large puddles!! I even remove the crank arms and covers to make sure its all clean would you recomend packing with silicone grease to prevent water ingress.
 

Bearing Man

Ebike Motor Centre
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Sep 29, 2018
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Yeah if i
Hi I've never used a power washer on the bike and only very briefly wash with hose in the crank area also the crank area has never been under water only through large puddles!! I even remove the crank arms and covers to make sure its all clean would you recomend packing with silicone grease to prevent water ingress.
Absolutely, definitely pack behind the seal with Silicone grease. If there is none there now, take the bike back immediately and demand a new motor. There should be a cover seal and grease to protect the bearing if it's not there or it's dry then that's a pre delivery inspection issue and not your fault!
As I said, even if you took the bearing out and re-greased it, it won't help, the bearings internal surfaces will now be pitted and this will cause it to fail prematurely.
I am so sorry to be the bearer of bad news, but please be assured, once it's fixed (replaced) and greased properly and frequently, especially at this time of year, you should be ok :)
 

Kbanny

New Member
Sep 27, 2018
14
9
Barnoldswick (LANCS)
Absolutely, definitely pack behind the seal with Silicone grease. If there is none there now, take the bike back immediately and demand a new motor. There should be a cover seal and grease to protect the bearing if it's not there or it's dry then that's a pre delivery inspection issue and not your fault!
As I said, even if you took the bearing out and re-greased it, it won't help, the bearings internal surfaces will now be pitted and this will cause it to fail prematurely.
I am so sorry to be the bearer of bad news, but please be assured, once it's fixed (replaced) and greased properly and frequently, especially at this time of year, you should be ok :)
Cheers for that the bike is back at the shop waiting for new motor to be fitted under warranty.im not sure if i have seen a cover seal when i have taken the cranks and sprocket off i can only see the sirclips on the crank spindle??
Is it any particular silicone grease you use to help protect and do you have any illustrations where I can see you put the grease ??
 

Bearing Man

Ebike Motor Centre
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Sep 29, 2018
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Cheers for that the bike is back at the shop waiting for new motor to be fitted under warranty.im not sure if i have seen a cover seal when i have taken the cranks and sprocket off i can only see the sirclips on the crank spindle??
Is it any particular silicone grease you use to help protect and do you have any illustrations where I can see you put the grease ??
Yup, it's all right here: How to video -
 

Kbanny

New Member
Sep 27, 2018
14
9
Barnoldswick (LANCS)
Shop just confirmed that the motor is on a 2yr rolling warranty so the 2 year starts again from when the new motor is fitted might aswell be a life time warranty coz I cant see it lasting 2 yr after mine went after 2 month. Unless they have done some good mods to it to prevent it happening this fast ?????
 

MattyB

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Jul 11, 2018
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Shop just confirmed that the motor is on a 2yr rolling warranty so the 2 year starts again from when the new motor is fitted might aswell be a life time warranty coz I cant see it lasting 2 yr after mine went after 2 month. Unless they have done some good mods to it to prevent it happening this fast ?????
There are too many of these motors out there in the wild for this to be a common issue - Bosch has one of the best reputations for reliability, and their motors have been around for a long time now. You must just have been unlucky and got a "Friday afternoon" motor - unfortunate, but it can happen with any brand. Remember these are complex pieces of kit operating in a relatively extreme environment, there are always going to be a few failures.
 

Doomanic

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Going to have to disagree with you there @MattyB. The Bosch motor has a known failure point in those bearings. My motor failed at less than 350 miles and there's a chap on the Pedelecs forum who had three go in 500ish miles of summer riding with the third motor to go failing at 97 miles!
Bosch have never to my knowledge admitted there is an issue, instead they quietly swap motors out on the rolling 2 year warranty.
 

MattyB

E*POWAH Elite World Champion
Jul 11, 2018
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Herts, UK
Going to have to disagree with you there @MattyB. The Bosch motor has a known failure point in those bearings. My motor failed at less than 350 miles and there's a chap on the Pedelecs forum who had three go in 500ish miles of summer riding with the third motor to go failing at 97 miles!
Bosch have never to my knowledge admitted there is an issue, instead they quietly swap motors out on the rolling 2 year warranty.
Seems like a strange business model if it’s true; fixing the issue would surely be cheaper than replacing all those motors?
 

Doomanic

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Seems like a strange business model if it’s true; fixing the issue would surely be cheaper than replacing all those motors?
Fixing motors is surely cheaper than a full recall.
 

TheBikePilot

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Oct 9, 2018
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Mine needed a new motor at 700miles. Dealer said to me ‘on the quie’ that was quite common with the motor but Bosch are standing by the warranty and changed it without a quibble..

They told me the motor was only valid during the 2 year bikes warranty but it was a real pain getting it back there as it was central London. I’ve got a Spesh now..So far so good..
 

Kbanny

New Member
Sep 27, 2018
14
9
Barnoldswick (LANCS)
Mine needed a new motor at 700miles. Dealer said to me ‘on the quie’ that was quite common with the motor but Bosch are standing by the warranty and changed it without a quibble..

They told me the motor was only valid during the 2 year bikes warranty but it was a real pain getting it back there as it was central London. I’ve got a Spesh now..So far so good..
Bosch changed there policy about 12 month ago and now the warranty starts again after the new motor is fitted my shop confirmed this today
 

Bearing Man

Ebike Motor Centre
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Sep 29, 2018
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I always feel we should look at the bigger picture. Bosch originally released their motors to be fitted into road bikes, in which, they do a bloody good job. The mountain bike manufacturers were the ones who started fitting these motors into mountain bikes (With the blessing of Bosch I'm sure) Whether it was realised at the time what an extreme environment an MTB operates in, I'm not sure.
What I do know is that in 2016 32.8 million ebikes were sold world wide. If Bosch only had 10% of that, it would be nearly 3.3 million motors out there for that one year alone.
Now look at how many complaints there are on all the forums you can find and it's probably less than 500! Even if 10 thousand people have taken a motor back under warranty, it's still only a failure rate of 0.3% Manufacturers would normally be more than happy with a figure like that. But if we looked more accurately at how many motors go back in a 1 year period, I would guess it's less than 2,000 world wide (Judging on the relative lack of complaints on the forums in a yearly period) Please bear in mind, a forum complaint is out there for ever, so when you look at "all" the complaints, a lot of them will date back 3 or 4 years.
So, if 2,000 motors went back in 2016 when, lets say 3.3 million were sold. That's a warranty failure rate of 0.06% Now the Bosch motor is starting to look pretty reliable. (which is annoying for me! :)) And out of that 2,000 motors that went back, how many failed because the owner jet washed it, or drowned it in a stream etc.
Just my two cents.
 
Last edited:

Welshman

Well-known member
Subscriber
Nov 8, 2018
220
132
South wales
I always feel we should look at the bigger picture. Bosch originally released their motors to be fitted into road bikes, in which, they do a bloody good job. The mountain bike manufacturers were the ones who started fitting these motors into mountain bikes (With the blessing of Bosch I'm sure) Whether it was realised at the time what an extreme environment an MTB operates in, I'm not sure.
What I do know is that in 2016 32.8 million ebikes were sold world wide. If Bosch only had 1% of that, it would be nearly 3.3 million motors out there for that one year alone.
Now look at how many complaints there are on all the forums you can find and it's probably less than 500! Even if 10 thousand people have taken a motor back under warranty, it's still only a failure rate of 0.3% Manufacturers would normally be more than happy with a figure like that. But if we looked more accurately at how many motors go back in a 1 year period, I would guess it's less than 2,000 world wide (Judging on the relative lack of complaints on the forums in a yearly period) Please bear in mind, a forum complaint is out there for ever, so when you look at "all" the complaints, a lot of them will date back 3 or 4 years.
So, if 2,000 motors went back in 2016 when, lets say 3.3 million were sold. That's a warranty failure rate of 0.06% Now the Bosch motor is starting to look pretty reliable. (which is annoying for me! :)) And out of that 2,000 motors that went back, how many failed because the owner jet washed it, or drowned it in a stream etc.
Just my two cents.
Need to check your maths

1% of 32 million is 320, 000
10% would be 3.2 million
 

Wiltshire Warrior

E*POWAH Master
Jul 3, 2018
563
228
Poole
After the mess I got mine in at the weekend (still getting mud out of the chain) I think I might retire mine until spring and go back to the clockwork bike until then
 

Bearing Man

Ebike Motor Centre
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Sep 29, 2018
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After the mess I got mine in at the weekend (still getting mud out of the chain) I think I might retire mine until spring and go back to the clockwork bike until then
That would be a shame :( If you think about it, your normally aspirated bike will probably need a new BB set by spring £20 - £70? But if you keep riding your ebike with plenty of silicone grease around the bearings it will be fine = £0 Or if it fails and under warranty you get a nice new motor = £0 Or if it's out of warranty, it will probably just be a main motor bearing £10 - £15 :D
 

TheBikePilot

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Oct 9, 2018
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How do I grease a Brose motor BB mate? I’ve a new 1.2 Motor on a 2017 model and keen to keep it in good nick until I send it to your an overhaul! Is it a case of removing the cranks etc? I’m mindful of the fact I probably don’t lubricate the moving parts well enough.
 

Bearing Man

Ebike Motor Centre
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Sep 29, 2018
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How do I grease a Brose motor BB mate? I’ve a new 1.2 Motor on a 2017 model and keen to keep it in good nick until I send it to your an overhaul! Is it a case of removing the cranks etc? I’m mindful of the fact I probably don’t lubricate the moving parts well enough.
Unless you do space ship mileage Jonny2, I wouldn't worry about it. The only bearing likely to fail through lack of lubrication is the small needle roller shaft bearing, but this normally dies because of belt dust, so adding more sticky grease or oil to it probably isn't going to help. Just ride and enjoy your bike with the piece of mind that if the worst comes to the worst, it can be fixed. Strip and re-grease maybe after 6,000? (Sorry to be vague but these motors have not been around long enough to know exactly what would be best as far as long term lube. In "nice" conditions they should be good for 10,000 to 15,000 miles.
The most important thing for any ebike motor is, if it starts making any different noises to normal (if out of warranty) STOP riding it and get it looked at!
 

TheBikePilot

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Oct 9, 2018
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Ok mate thanks. I’ve been guilty in the past of Ride and forget, just splashing a bit of oil on the chain every now and again and I’m keen to keep this one in the best nick I can.

The motor was replaced from a 1.1 to a 1.2 on Oct 6th so I should be good for a while.

Only thing is where I ride in the surrey hills it has very fine grit like sand that gets into everything, including every crevice on my flooring at home (bike stays in my flat) so it needs a deep clean. I don’t use a pressure washer just enthusiastically use the hose. Am I right it saying not to drench the motor casing..?

Thanks again. J2
 

Bearing Man

Ebike Motor Centre
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Sep 29, 2018
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UK
Yeah, you're right. Just use a sprinkler attachment for the motor. Ideally wet it, soft brush with what ever cleaner you use, drag the muck from behind the sprocket etc. (Found a hooked engineers scribe is excellent for this) Then sprinkle of and soft brush, what ever you normally use. Re-grease the seal now and then (depending on your riding conditions, washing etc.).(y)
 

LawmanMtb

Member
Aug 15, 2018
142
49
Wigan
my motor is being replaced as i type, 600 miles on it, any chance of a pic of where i need to apply the silicone grease please?
 

SquireRides

E*POWAH Elite World Champion
Sep 4, 2018
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UK
my motor is being replaced as i type, 600 miles on it, any chance of a pic of where i need to apply the silicone grease please?

Take a look at this pic from a UK shop selling spare seals: Bosch Performance / Active / CX Main Bearing Seal

Once you take off your crank arm and remove the chainring (using the Bosch locking tool), it will look like this. Carefully remove the black seal (it's a bit tricky because it is a good tight fit). Then fill the space behind with grease. Push the seal back on and wipe away the grease that splurges out. Job done.
 

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