Loose motor

[Pmc1]

Hi,
I've recently fitted a bafang bbs01 motor to my wife's cannondale full suspension bike.
I'll post some pics when we get back from our holiday.
Yesterday after returning from a 30 mile canal towpath ride I noticed that the motor was hanging loose from its mounting bracket.
The two nuts holding the motor tight against the bottom bracket had come loose.
I tightened the nuts with a pair of pipe pliers - the correct tools being at home - and zip tied the motor to the frame as an additional support.
Today's ride showed no loosening of the motor.
Is this a common problem?
The manual says to torque the nuts to 50nm, should they be tighter than this?
Any advice appreciated.

 

[soundwave]

lock tight

 

[Woosh]

The two nuts holding the motor tight against the bottom bracket had come loose.

Make sure that the triangular bracket is correctly mounted with the ridges to the inside so they key into the bottom bracket shell when you tighten the first M33 lockring. That will stop the motor from rotating. I usually tighten the first M33 lockring with a C spanner.
The second M33 is there to stop the first from spinning loose. You don't have use much torque on the second lockring..

 

[tommie]

I usually tighten the first M33 lockring with a C spanner.

Make very sure this is super tight, if using a C spanner put a length of pipe on the end and stand on it.

 

[Deleted member 4366]

A few people have had that. It's just a question of how tight you screw up the locking rings. That's if you fitted both.

Obviously if you had a bike with press-fit bottom bracket bearings, you'd need to add a tie-bar of some sort.

 

[Nixtoo]

I frequently tighten my mid drive motor. I carry the c spanner when i’m out just in case I see movement!

 

[Pmc1]

Thanks for all the replies.
I'm back from holiday now so will take all your advice.