Stop BB02 Rotating on a Recumbent

[SubRider]

I'm installing my Bafang BB02 to the frame of my Optima Falcon 'bent (not to the BB shell way out at the end of the front boom).
The motor mount is a custom U-bracket, which takes the place of the BB shell in a typical BB02 mounting. The BB02 mounts to the U-bracket and that mounts to the frame.

An issue is that the "toothed" Bafang plate (which bolts to the electric motor frame) does not bite into the U-bracket (which has a lot more surface area than the edge of a BB shell.

I've been looking for toothed washers, but washers that are big enough are rare.
I'd rather not use an adhesive.
It is easy enough to drill bolt holes to fix the left side, but that is not an easy option for the right side because I don't want to drill into the gear housing.
I prefer to fix both the left and right sides.

Do you know of a solution?
Perhaps a thin "toothed sheet of metal that can be cut into something like a large toothed washer.

Cheers,

 

[Rassy]

I'm having trouble envisioning how you are putting this system together, but the "toothed" washers are there mainly to prevent the Bafang from slipping "backward" in my opinion. On a normal installation the Bafang is positioned against the down tube to prevent the torque of the motor from making it spin so the washers really have no role to play at that point.

However, on my tadpole trike I did install the Bafang in place of the crank out on the end of the boom. I could have rotated the motor up until it contacted the tube that is installed for mounting the front derailleur, but partially for looks and partially because the built in drain holes for the Bafang would not be at the bottom, I decided to let it hang down, thus creating the same problem you are experiencing.

My plan A is working, which was to make a small plate that ties the Bafang shell to a little tit that is on the frame of my trike and meant to guide the cable that originally ran to the front derailleur.

plan B would have been to attach something to the frame that was shaped to hold the Bafang from turning.

I can't provide a picture at this point, because I'm going out of town for a few days of riding and the trike is already loaded in my car.

Good luck with your solution and I'd like to see a picture of the system.

 

[xrpb11a]

Hi Rassy,
I am also putting a Bafang BB02 on the end of the boom of a HPV StreetMachine and want to hang it straight down for the reasons you state.
When you get back can you post a picture of your bracket that holds the motor?
I'll need to make one too!
Thanks,
Bob.

 

[Rassy]

Here's a picture of the bracket (torque arm?) that I made for my BBS02. The first one was made out of a piece of 1/16" aluminum and the first time I hit the throttle hard in too high of a gear it broke out at the BBS02 bolt. I found a piece of 1/8" aluminum and made a new one, which has held up for hundreds of miles so far. I seldom use the throttle, which quickly ramps up to full power. When I do want to use the throttle I wait until the PAS system has engaged the motor and ramped up some power, even in assist level 1, which keeps the Bafang from "jerking" the chain.

The other item in the picture is a rusty old wrench that came with a circular saw. If the aluminum piece breaks again I'll make a new bracket out of the wrench.

The hose clamp is there to keep the bracket tight against the boom.

 

[tahustvedt]

Here's a picture of the bracket (torque arm?) that I made for my BBS02. The first one was made out of a piece of 1/16" aluminum and the first time I hit the throttle hard in too high of a gear it broke out at the BBS02 bolt. I found a piece of 1/8" aluminum and made a new one, which has held up for hundreds of miles so far. I seldom use the throttle, which quickly ramps up to full power. When I do want to use the throttle I wait until the PAS system has engaged the motor and ramped up some power, even in assist level 1, which keeps the Bafang from "jerking" the chain.

The other item in the picture is a rusty old wrench that came with a circular saw. If the aluminum piece breaks again I'll make a new bracket out of the wrench.

The hose clamp is there to keep the bracket tight against the boom.

You need more leverage for your torque arm. At 80 Nm torque the force at the bolt point is 300 lbf if the BB nut isn't holding, so no wonder it ripped up the 1/16". The bottom bracket clamping nut doesn't stand a chance against that kind of force on its own.

It's unclear to me why you don't just let the motor swing up and sit against the tube om top though.

 

[Rassy]

tahustvedt wrote:

You need more leverage for your torque arm. At 80 Nm torque the force at the bolt point is 300 lbf if the BB nut isn't holding, so no wonder it ripped up the 1/16". The bottom bracket clamping nut doesn't stand a chance against that kind of force on its own.

It's unclear to me why you don't just let the motor swing up and sit against the tube om top though.

You're right, and it probably wouldn't work for a hot rodder, but I ride for pure pleasure and a little exercise. Since the Bafang was designed to hang down on a standard bike, the controller housing has a couple of weep holes that would be on the top in the other position. If necessary, I will take the Bafang apart and drill out a couple of new weep holes and let it swing up against the tube on top of the boom, but in the meantime. I also like keeping that extra weight down low.

 

[xrpb11a]

I wonder how one of these would hold up instead of the c clamp..

http://t-cycle.com/seatside-mount-system-c-117/seatside-mount-system-hardware-c-117_119/heavy-duty-frame-clamp-p-278.html

turn the so the M6 bolt holes on the frame clamp are parallel with the motor bolt. Then it's bolted on both sides...

Here's a picture of the bracket (torque arm?) that I made for my BBS02. The first one was made out of a piece of 1/16" aluminum and the first time I hit the throttle hard in too high of a gear it broke out at the BBS02 bolt. I found a piece of 1/8" aluminum and made a new one, which has held up for hundreds of miles so far. I seldom use the throttle, which quickly ramps up to full power. When I do want to use the throttle I wait until the PAS system has engaged the motor and ramped up some power, even in assist level 1, which keeps the Bafang from "jerking" the chain.

The other item in the picture is a rusty old wrench that came with a circular saw. If the aluminum piece breaks again I'll make a new bracket out of the wrench.

The hose clamp is there to keep the bracket tight against the boom.