deepfraught wrote:Does the installation use the bottom bracket threads, or does it thread one side of itself into the other, floating in the BB and clamping itself to the faces?
The latter is basically the case -- the axle assemble is inserted into the BB shell, with a threaded retaining ring (and a locking ring, depending on BB width) compressing the unit against the BB faces. The internal threads on the BB shell do not come into play.
Incidentally, in some other threads, people were worrying that this would damage the BB shell internal threads, such that a normal BB couldn't be re-installed. I don't think this would be the case, because the threads are cut into the the shell, rather the shell being cut away from the threads.
I’ve had BBS02 on a Raleigh 20 for about 300 miles of riding.
Like the kit a lot, but decided it was overkill on a bike with 20” wheels, and I would move it to a bike with larger wheels.
So I dis-assembled the Raleigh 20 / BBS02 build yesterday, and rebuilt the Raleigh 20 to its original configuration… eg, reinstalled original bottom bracket, etc.
Did have one problem.
The BBS mounting plate has small ‘protrusions’ that dig into the steel of BB shell and serve to fix the motor assembly in place relative to the bike frame.
Turns out those protrusions did deform the outermost BB shell threads slightly. I fixed the problem by filing down the BB shell very slightly (~1mm) to remove the deformed section of thread. Was then able to reinstall original bottom bracket.
Maybe more concerning: there was some evidence that the torque of motor had in fact been rotating the entire assembly slightly within the BB shell. I expected to find a single, sharp, V-shaped indentation in the steel of BB shell from each of the mounting plate ‘protrusions’. In fact, I found that each of the indentations was a bit wider than expected. Instead of a perfect V shape… each indentation was shaped more like \_/ That is, each of the indentations was slightly wider than expected.
Retaining ring and locking ring were torqued down tight when originally installed, the BBS02 was not movable by hand force, and the retaining ring and locking ring showed no signs of having loosened since the original installation. My best guess is that the power of the motor was resulting in very slight rotation of the entire assembly within the BB shell over time... eg, the mounting bracket 'protrusions' weren't sufficient keep it perfectly static, and the steel of BB was deforming slightly over time. If so, that is kind of worrisome.