Stating a fact: Bafang BBSxx motors have a bottom bracket shaft diameter of 33.5 mm and are designed to fit into the bicycle bottom bracket standard known as JIS or Japanese Industrial Standard, which is very similar to our standard here in the US commonly referred to as "square tapered spindle", ISO/English.
I purchased a BBS02 from Johnnynerdout, but it didn't fit my Cannondale Hybrid, which has a slightly smaller bottom bracket shaft diameter. So now I am looking for a used bike which matches that standard. It is hard to find the bottom bracket specs for potential bikes. For example. the Trek 7.3 FX hybrid. Any advice would be appreciated.
I had hoped the 95% number is true, but am just unlucky I guess. The first 2 bikes I wanted to mount the motor on were fails, as they are Cannondale (one I own) and Trek (one I found second hand). As you can see from the linked article, Trek bikes are incompatible with the BBS02. And when we tried to mount the motor on my Cannondale Quick-4 it wouldn' t fit. The Bottom Bracket "socket" was a couple mmm too small. So even though it says in this article (below) that it should fit, we could not figure out why it did not.
https://www.empoweredcycles.com/blogs/news/101474694-bottom-bracket-standards-and-bafang-mid-drive-motors#
"BB30: This was introduced as a new international standard utilizing a new, larger-diameter crank spindle and bottom bracket shell. With BB30, 42mm bearings press into the frame against inner snap rings. This is an open standard, like ISIS, that was originally introduced by Cannondale and has been adopted by crank manufacturers FSA, SRAM, and Zipp. If your bike has a BB30 bottom bracket, no worries, just get a BB30 to BSA adapter and the Bafang BBS02 or BBSHD will fit beautifully. Make sure to buy either a 68mm or 73mm BBSxx because BB30 is only made in these two widths. BB30 = good :"