- Jul 14, 2011
Bombing down the hill at Kilbrogan
The idiot software of this board just lost my complete description of the installation and use of a Bafang BBS midmotor with a Rohloff hub gearbox because it claimed it was over 10K words. What sort of a motherless programmer writes a deadend loss like that with no return path?I'd love more info as i want to do a similar rohloff build and need info re alternate chainrings/chainline etc . PLEEEEEZ update!
bill in exeter
I don't have time to rewrite all of that for five people to read, Bill, so I'll just answer your specific questions and in future place my complete review someplace safer.
Bill "need(s) info re alternate chainrings/chainline etc"
The Rohloff chainline demanded by Bernd Rohloff is within 1mm of 54mm, measured from the centreline of the hub (on a well-built from from the centreline of the seat tube!) to the longitundinal centreline of the teeth on the chainring, i.e. to the middle of a roller on the chain if it doesn't fit too loosely.
The offset of a standard dished chaingring for the Bafang BBS mid-motor is 51mm. I used 3.5mm total of spacers, as 2.5mm and 1mm, mainly because I already had them and they were already painted bike color, between the bottom bracket shell and the rear ride of the motor supposed to rest on the bottom bracket shell's rim. This moved the chainline to within 0.5mm of the desired chainline.
Practical measurement is from the far (non-driveside) of the seat tube to the centre of the thickness of the teeth, minus half the diameter of the seat tube.
Spacers you can buy from Chainreactioncycles.com, which is where I got mine, as either dedicated bottom bracket spacers or, if you can determine that they have the same inner and outer diameter as your bottom bracket shell, as cheaper and often generic sprocket spacers.
I don't know what "etc" is. If you have a specific question, ask here and I'll try to answer. Good luck with your build, Bill.