Over-torqued Motor Mount Bolts?

[E-MAD MALC]

Either poor design/QC or cheap/inferior methods used. That tiny amount of material on a crucial structural part of the frame is a joke. Throw in incorrect torque values and then cube refusing warranty claims on the basis of 'wear and tear'!

Yep I've got to agree with you on that
I would have thought they could incorporated metal into the fixing points

 

[Spiff]

I believed that it was standard practice in carbon frames to have metal inserts for frame suspension bearing sockets, and also for the motor mount drills, but I am no longer sure

 

[Hattori-Hanzo]

I took one of these bolts out today to check the mount.
Note that other than the factory fitment these bolts have always been tightened to 12nm. You can see how the carbon is deforming under the bolt head.

There is a metal insert bonded to the mount hole, but it's very thin.

Time will tell I suppose. I'm going to continue to ride as I am, mostly bike parks and keep on top of maintenance.
I'd urge anyone with the Cube stereo hybrid 160/140 to regularly check these bolts aren't coming loose.

I'd still be interested to see how other manufacturers are mounting the Bosch cx motor as I'm sure I've seen trek using a very similar set up.
I think @irie has recently had his motor out of a trek bike?

 

[irie]

I took one of these bolts out today to check the mount.
Note that other than the factory fitment these bolts have always been tightened to 12nm. You can see how the carbon is deforming under the bolt head.

There is a metal insert bonded to the mount hole, but it's very thin.
View attachment 145148

Time will tell I suppose. I'm going to continue to ride as I am, mostly bike parks and keep on top of maintenance.
I'd urge anyone with the same bike to regularly check these bolts aren't coming loose.

I'd still be interested to see how other manufacturers are mounting the Bosch cx motor as I'm sure I've seen trek using a very similar set up.
I think @irie has recently had his motor out of a trek bike?

Was taken out, serviced, and re-installed by the eBike Motor Centre, so best to ask @Bearing Man

 

[Bearing Man]

Was taken out, serviced, and re-installed by the eBike Motor Centre, so best to ask @Bearing Man

We always try to re-install to the bike manufacturers torque specifications, but 12Nm seems way too low to stop a motor moving around! Although looking at the photo in @Hattori-Hanzo post, I would be reluctant to go much tighter.

 

[Bummers]

I took one of these bolts out today to check the mount.
Note that other than the factory fitment these bolts have always been tightened to 12nm. You can see how the carbon is deforming under the bolt head.

There is a metal insert bonded to the mount hole, but it's very thin.
View attachment 145148

Time will tell I suppose. I'm going to continue to ride as I am, mostly bike parks and keep on top of maintenance.
I'd urge anyone with the same bike to regularly check these bolts aren't coming loose.

I'd still be interested to see how other manufacturers are mounting the Bosch cx motor as I'm sure I've seen trek using a very similar set up.
I think @irie has recently had his motor out of a trek bike?

You've highlighted the problem perfectly. Tiny amount of CF to hold the metal insert. 12nm seemingly a low value to grip a high stress area yet any higher torque and it'll crush what little CF there is.
It's a proper design flaw on a bike with 170/160 suspension for gnarly downhill riding yet built for canal paths.

 

[Mikerb]

The issue is that at the bb the frame designer is using lugs which not only have enable sufficient bolt torque but also the other forces created by the cranks.......and forces inflicted if the bash guard is hit.
In my opinion the proper way to deal with that would be to fix a metal framework to the carbon frame with probably 3 fixing points each side.....and then bolt that framework to the motor.

 

[Hattori-Hanzo]

So are Cube completely oblivious or are failures only starting to show now? I believe this mount design has been around since 2018 and is also continued on the new Cube 155.

Mike makes a good point, could these failures also be caused by heavy hits to the underside of the motor, also seems likely.

What Mike describes is exactly what someone did who's frame suffered a failure. They fixed a metal bracket to the back of the frame that wrapped round the sides of the motor.

 

[Bummers]

So are Cube completely oblivious or are failures only starting to show now? I believe this mount design has been around since 2018 and is also continued on the new Cube 155.

Mike makes a good point, could these failures also be caused by heavy hits to the underside of the motor, also seems likely.

What Mike describes is exactly what someone did who's frame suffered a failure. They fixed a metal bracket to the back of the frame that wrapped round the sides of the motor.

It's hard to quantify without knowing the number of failures, how the bikes are used etc. Also how many are even aware their mounts have cracks or damage but not yet detected by the rider.

All I'm going off is the growing number of complaints I'm seeing on the FB group, the bizarre mixed information on cube regarding the torque values and worst of all the lack of accountability when it comes to warranty claims. This is not a 'wear and tear' part.
I'm very disappointed in how they've handled it.

 

[Stihldog]

For pedals and suspension bolts, I apply anti-seize grease

ANTI SEIZE - BIKE LINE

MOTOREX ANTI SEIZE is a special mounting paste for metal and aluminium connections including any parts that need to be press-fit, aluminium supports in metal frames and all screw connections.

motorex.com

I use to have a small tin of this stuff many years ago. If I recall, it had a copper-like colour and a small brush was used as an applicator.

I should probably add this to my lotions n’ potions. Servicing certain things with this stuff makes sense.

 

[Bearing Man]

I use to have a small tin of this stuff many years ago. If I recall, it had a copper-like colour and a small brush was used as an applicator.

I should probably add this to my lotions n’ potions. Servicing certain things with this stuff makes sense.

Don't ever use this stuff for your motor mounts! That would be bad news.

 

[B1rdie]

When my cube 160 started making noises at bottom bracket and I went to undo the bolts (+- 1 year of use), the precision torque meter showed 8nm - 12nm , after torquing back to 20 nm no more noises for another 1 year.
So, I'd say that 11 nm is not enough and maybe will let some play that in the end will wear the fixing points like the picture above of hattori's bike.

 

[Stihldog]

Don't ever use this stuff for your motor mounts! That would be bad news.

I agree …a little dab of blue loc-tight is what I use here.

 

[Hattori-Hanzo]

When my cube 160 started making noises at bottom bracket and I went to undo the bolts (+- 1 year of use), the precision torque meter showed 8nm - 12nm , after torquing back to 20 nm no more noises for another 1 year.
So, I'd say that 11 nm is not enough and maybe will let some play that in the end will wear the fixing points like the picture above of hattori's bike.

And here we are back full circle to 20nm, backed up with an email from Cube as @MrPeaski shows.

So 11 or 20, who knows

Think I'll go 15nm with quality thread lock

I suspect Cube will try to brush this under the carpet if it is a genuine frame issue, imagine the recall cost for all stereo hybrids sold since 2020!
And a fix won't be easy.

Might be worth starting a thread in the Cube forum so everyone's information can be gathered?