torque arm for bsob750w motor

[willcee]

With this in a good alloy hybrid Merckx frameset and having cycled approx 170 miles i am finding that despite my endeavours , I am a cycle mechanic, the motor is becoming loose and twisting downwards.. I realise that the 160n/m torque has a bearing and ime the std fitment set up isn't up to holding that sort of power for very long nor do I want it chafing up a tidy frame..I've seen a couple of endeavours to combat the twist but heath robinson and obtrusive would be a decent description.. subtle would be my way.... any one any answers?? will

 

[Fordulike]

Firstly, have you installed the bottom bracket motor mounting plate, with the knurled side facing inwards? This will ensure the plate bites into the bottom bracket, to help prevent torque from twisting the motor.

Secondly, make sure you use the proper tool to tighten the inner nut and locking collar tight, and I mean really really tight. Until your hand bleeds...... Ok, maybe not that tight lol.

 

[peter.c]

This solved my problem, California ebike shop in the us but the post was not cheap, it rivnuts to the frame https://california-ebike.com/shop/bsbf-1-bafang-stabilizer-bar-full-suspension-bike-bbs0102-bbshd/ hope this helps https://california-ebike.com/shop/bsb-1-bafang-stabilizer-bar-bbs0102-bbshd/ or this one

 

[tommie]

Will, i`ve two bikes with the BBS02/HD conversions, you really have you tighten that inner nut with an awful degree of ignorance!
Whatever you`re using get a length of pipe and stand on it, don`t worry it won`t strip the threads.
this is what i done here, no motor movement on both bikes..

 

[willcee]

thanks,i've likely built more bikes than most of the people who contribute here so when i say its tightened and with the plate correctly orientated rest assured its so.. The pic which peter c above sent looks proper and it would certainly contain any inappropriate movement....i have one on order.. will

 

[willcee]

Luna cycles spanner and torque arm here and fitted, but Realistically how do Bafang think that 2 nuts done up as tight as some have suggested will suffice to stop 160n/m or in old school 116lb/ft of torque from getting loose,, that torque which can haul a ton vehicle to over 100mph.. mines on a road bike its not spinning jumping and dropping over jumps as the MTB guys will be.. get a torque reaction clamp they fit over the Bafang yoke and are the proper shape to fit against the underside of the downtube. no real fettling needed.. will

 

[tommie]

Realistically how do Bafang think that 2 nuts done up as tight as some have suggested will suffice to stop 160n/m or in old school 116lb/ft of torque from getting loose,, that torque which can haul a ton vehicle to over 100mph

Never had a problem on the two BBS converted bikes here, and i`ve seen the display on the HD bike pull well over 1400w many times on these hills.
All i can think of in your case is possibly the frame material doesn`t grab that first serrated nut as tight enough as other frames.
Like i said before, proper spanner with length of pipe and stand on it.

 

[wheeliepete]

The torque of the motor pushes the motor into the frame, not away from it, so, as Tommy has said, if the motor is secured tight enough, there's no problem. Applying normal bike building technique to an electric bike does not always work, as you have found out Will. I'm glad you have found a solution to your problem, but those brackets do not work on every build.

 

[willcee]

Thanks Guys,i suppose my extended experience in race cars rallye cars and race bikes doesn't count here in your opinion.. all i can say is to me its a bit like fitting any engine with just one engine mount and expecting it to handle all the associated torque actions and reversals.. my experience and obviously Lunas would suggest other than your acceptance of Bafangs offerings.. will

 

[peter.c]

I am glad you solved your problem the luna bracket is a well thought out well made product and it gives and easy answer to odd bottom bracket problems