bafang motor with stabilizer bar - not so stable

[martinw]

Hi,

I noticed that my bbs01 motor is not fixed enough by stabilizer bar (https://california-ebike.com/shop/bsb-1-bafang-stabilizer-bar-bbs0102-bbshd). It's slightly moving (+-1mm ~ 0.04inch) inside of low bottom bracket (picture below). In my opinion that M33 axle nut is really tight ~ 50-60nm.

Do you think that current mounting of the motor could damage my frame in long-term perspective ? Sadly I do not have enough space to put original fixing plate together with stabilizer bar (wide 29er frame). What would you do ?

 

[markz]

Hmmmmm was the part precisely machined so the BB hole was snug and flush?
Perhaps with the movement it just got worse and worse.
Is your Bottom Bracket in tip top shape.
Bolt hole mounts for bracket are a tight fit with bolt?
When you move it with your hand you can feel it move can you. Not sure what else to check.

 

[martinw]

it's precisely machined and bottom bracket is fine. Main difference is that stabilizer bar does not 'bite' to the side of bottom bracket. I will try to put more torque on M33 nut.

Also I will have to mount motor somehow to downtube (e.g. steel hose clamps - large diameter) - currently there is no direct contact with downtube there's 12mm space (due angle of the stabilizer bar).

 

[markz]

The only better quality hose clamps I have seen are these type.

https://www.princessauto.com/en/detail/3-81-to-4-13-in-t-bolt-hose-clamp/A-p8251159e

I dont know about using rubber on the inside of the hose clamps, sure it saves the paint on the bike.

 

[E-HP]

Main difference is that stabilizer bar does not 'bite' to the side of bottom bracket. I will try to put more torque on M33 nut.

If you think adding ‘bite’ would help, you use a 20 LPI metal checkering file to add sharp teeth to to part of the stabilizer that contacts your bottom bracket to see if that would lock it into place better.

 

[Rassy]

Edit: Sorry, I reread your first post and you have pretty much done what I said. Perhaps a small block of hard rubber or some such item between the motor and the down tube would eliminate the tendency it has to apply too much torque for your brace to control.

Since the motor's torque is towards the down tube I have found that the best solution is to have the motor snug against the down tube. Then with everything tight there should be no movement. All clamps, braces, etc. should compliment keeping the motor tight against the down tube.

Having said all that, on my tadpole trike, I didn't want the motor up above the boom where it could be against the stock post that originally held the front derailleur in place. So in addition to the stock bracket I added the custom stabilizer made by LUNA, which has worked out great;

https://lunacycle.com/bsb-1-stabilizer-bar-for-bbs02-and-bbshd/