Bosch cx motor failed again 4th

EddiePJ

Esteemed Pedelecer
Jul 7, 2013
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Crowborough, East Sussex
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I'd say that the comment came from a clueless dealer, rather than any representative from Bosch.

Ask the dealer to expand upon the comment, preferably in writing.
 
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Jst_at_home

Pedelecer
Jul 8, 2014
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I'd say that the comment came from a clueless dealer, rather than any representative from Bosch.

Ask the dealer to expand upon the comment, preferably in writing.
I'm certainly hoping so! I'm hoping that the motor will be back later this week. I'll post an update when I get the bike back.

John
 

Bearing Man

Trade Member
Hi all

I have a Cube Cross Pro with the Bosch CX Performance motor. It has been fine for the last 20 months and almost 4,000 miles. On road use only.

Last Monday, I seemed to lose drive assistance in that it felt as if teeth on a ratchet had failed or a gear had stripped. I could get some assistance on a level road with light pedalling but with any pressure, the pedals were almost free-wheeling.

I took the bike back to the supplying dealer who investigated and have sent the motor to Bosch. I am a bit concerned that the bike dealer made some comment about Bosch having suggested that the fault may be down to "poor maintenance".

I'm still in the warranty period but beginning to wonder if I'm going to be stung with a big bill if they do claim poor maintenance.

My bike has been well-maintained (I'm a Transport Manager) but it's disappointing since the Cube has only dome marginally better than my previous Kalkhoff before a major failure.

Does my fault description sound familiar to anyone else?

Many thanks

John
The symptoms you have John are normally a cracked drive gear. It is a fairly common fault and a 5 minute fix. If Bosch throw this back at you, tell them to look at the small metal drive gear that houses the small motor drive gear clutch bearing.
 

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Jst_at_home

Pedelecer
Jul 8, 2014
36
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The symptoms you have John are normally a cracked drive gear. It is a fairly common fault and a 5 minute fix. If Bosch throw this back at you, tell them to look at the small metal drive gear that houses the small motor drive gear clutch bearing.
Many thanks for that info, Bearing Man. It's very helpful. Given that the supplying dealer made the comment, could this have been the result of "poor maintenance"?

John
 

soundwave

Esteemed Pedelecer
May 23, 2015
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if the motor is in warranty you will just get a new one as dealers can not fix motors in warranty they cant even open them.
 
D

Deleted member 25121

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The symptoms you have John are normally a cracked drive gear. It is a fairly common fault and a 5 minute fix. If Bosch throw this back at you, tell them to look at the small metal drive gear that houses the small motor drive gear clutch bearing.
Would that void any Bosch warranty or are you Bosch approved to service their motors?
 

Bearing Man

Trade Member
Would that void any Bosch warranty or are you Bosch approved to service their motors?
Although we are Bosch approved, no one but Bosch are approved to repair their motors. This is why we only work on motors outside of warranty or motors that people don't want to wait for warranty and are prepared to forgo it.
This failure is not a service or maintenance issue, it's just one of those things that happens very, very occasionally with this motor.
 

Jst_at_home

Pedelecer
Jul 8, 2014
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Hi all. Still waiting for an update from Bosch. I thought they might have been a bit quicker!

Bike shop tells me now that the problem they identified was that the splined shaft that the chainring fits in had stripped, albeit that the nut that secures the chainring was correctly torqued.

I have to say that I had cleaned the bike and checked the chain the previous day and had not been aware of movement at either the chainring or the rear gear set.

Anyone else had this?

John
 

Bearing Man

Trade Member
I see this a lot, especially if the wrong type of sprocket has been fitted with the wrong type of nut. What happens is the nut bottoms out and goes tight before it clamps the sprocket tight enough. This allows the sprocket to move and it can cut through the aluminium sprocket carrier surprisingly quickly.
If Bosch don't honour the warranty (which would be understandable if the sprocket has cut through the carrier). Because you have been off the road and messed around, we will fix your motor for £25.00 at performance Line Bearings, you just pay the postage. Email me at enquiries@performancelinebearings.com if you think this option would help.
 

soundwave

Esteemed Pedelecer
May 23, 2015
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when i first got my bike in 2014 the lock ring was plastic :eek:
 

Bearing Man

Trade Member
when i first got my bike in 2014 the lock ring was plastic :eek:
Yes, I have seen a few of those. Bosch didn't keep that idea very long did they :)
 
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soundwave

Esteemed Pedelecer
May 23, 2015
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i broke mine trying to take it off with a hammer and screwdriver, it broke in half lol.
 
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Jst_at_home

Pedelecer
Jul 8, 2014
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I see this a lot, especially if the wrong type of sprocket has been fitted with the wrong type of nut. What happens is the nut bottoms out and goes tight before it clamps the sprocket tight enough. This allows the sprocket to move and it can cut through the aluminium sprocket carrier surprisingly quickly.
If Bosch don't honour the warranty (which would be understandable if the sprocket has cut through the carrier). Because you have been off the road and messed around, we will fix your motor for £25.00 at performance Line Bearings, you just pay the postage. Email me at enquiries@performancelinebearings.com if you think this option would help.
Many thanks. I have to say that I haven't been aware of any "float" on the chainring. However if the worst comes to the worst, I may well be in touch. When you say you see this a lot, is this on new bikes or ones that have had repairs which have seen wrong type of sprocket/nut fitted?
 

Bearing Man

Trade Member
Many thanks. I have to say that I haven't been aware of any "float" on the chainring. However if the worst comes to the worst, I may well be in touch. When you say you see this a lot, is this on new bikes or ones that have had repairs which have seen wrong type of sprocket/nut fitted?
I mostly see it on fat bikes, where the sprocket has been made by the manufacturer to stick out further to help the chain miss the rear tyre. These seem to put a high side load on the sprocket and some definitely become lose. But often, it's caused by fitting the wrong sprocket.
 

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