Installing an electric mid-motor

[IanW]

Hi Andre, Ian,

It looks like I too might be heading down the BBS01 (350w) ebike conversion route.
(No, I am not trying to do this to my RST)
But I am looking at the possibility of doing this conversion to a bike with 73 mm bottom bracket shell width.

Various descriptions of the BBS01 seem to indicate that it will only fit bottom bracket shells between 64 mm and 68 mm in width.
While other descriptions seem to indicate that it could work with widths up to 73 mm.

So my specific questions, if you are prepared to answer them, are:

1) What width of bottom bracket shell did you [successfully] fit the BBS01 to?

2) How much thread, if any, remains exposed after the mounting bracket + 2 lockrings have been installed?

Thanks
Ian[W]

[Andre Jute]

1) What width of bottom bracket shell did you [successfully] fit the BBS01 to?

68mm.

2) How much thread, if any, remains exposed after the mounting bracket + 2 lockrings have been installed?

This is a bit trickier. BBS chainline out of the box in a 68mm bottom bracket shell is 51mm. So I fitted spacers to the drive side to get a 54mm Rohloff chainline.The spacers are fitted flush to the end of the bottom bracket shell on the drive side (i.e. over the "bottom bracket" integrated into the motor, by which the entire shebang hangs on the bike, moving the entire motor assembly to the right). Since my spacers are painted the bike color, they're damned difficult to see but I think I fitted either 2.5mm or 3.5mm because I didn't have the precise 3mm. In any event, that left enough thread for both lockrings to be fitted on the non-drive side. There is however no leftover thread visible on the "bottom bracket" axle on my bike.

So, if you do without the spacers, as you would, you should have enough thread to use the BBS with a 73mm and that should give you a 53.5mm chainline, well within the 1mm tolerance demanded by Rolloff. If there isn't enough thread for both lockrings, a spot of Locktite on a single lockring will see you right.

Here is an additional data point of someone who intended building a BBS01 into an Ogre with a 73mm bottom bracket shell.
http://www.pedelecs.co.uk/forum/threads/rohloff-speed-14-hub-gearbox-with-bafang-bbs-mid-motor.22386

[Andre Jute]

 
It seems there is a minimum of easy adaptation required to fit the Bafang BBS01 to a 73mm bottom bracket. This is from a large supplier of kits:

[macspud]

Andre, I thought you may enjoy this eight part series of videos at Bafang.
Playlist: https://www.youtube.com/playlist?list=PLMsufmMBrYpAGX8HowBJJ_HSBRxruYrMi

They certainly have plenty of testing for quality control.

[Andre Jute]

Thanks! I'll get back to you when I've watched them all.

[Andre Jute]

Andre, I thought you may enjoy this eight part series of videos at Bafang.
Playlist: https://www.youtube.com/playlist?list=PLMsufmMBrYpAGX8HowBJJ_HSBRxruYrMi

They certainly have plenty of testing for quality control.

Fascinating, MacSpud. Thanks for the link. Bafang, clearly a serious operation, in their upmarket 8FUN persona also has a Swiss-based research and testing station. That's why when I first recommended them to forum members, several years ago now, I specifically recommended the QSWXK, in which the Q indicated that it was a special quality-controlled version of the SWXK (their highest torque model that was also legal) that was specified and inspected by the Swiss end of their operation, specifically aimed at picky (the Chinese probably described us as something less flattering like whatever the Mandarin for "pernickerty" is) European customers; they apparently believed that Americans could be palmed off with the same stuff they sold in China.