Help with Bafang conversion kit choice

[CJaMTB]

Hey all,

I'm looking to buy a fatbike, with a 100mm BSA BB, and am really lost as to what my choices are from Bafang. If possible, I'd like something in the region of a 60nm motor and a battery in the region of 600-700wh (though ideally say 450-500 with a range extender, if that's even a thing?!?), the whole system must be UK road legal (15.5mph cutout). I'd also like to have a torque sensor on the crank, again if possible. I've never done a conversion before, though am a long time bike mechanic and a former physicist, so the process isn't a problem, knowing which kits to look at is. Any and all help is very gratefully received!

 

[mike_kelly]

A good reference is the Bafang workbook.

https://bafang-e.com/fileadmin/Images/service/BAFANG_Workbook_OEM_2023.pdf

 

[CJaMTB]

Thanks Mike, much appreciated

 

[mike_kelly]

When you are wanting to retrofit to an existing bike there are limited options. I am NOT an expert but the mid-drive bottom bracket motors tend to be like the Bafang BB series. THe BBSHD and the BBS01 etc. They are fairly commonly available and I think have 100mm BB options but they are monster motors, relative to the 60nm you asked about, with 150nm of torque. all the more modern motors like the M820, which is 75nm, require a made for the motor frame. You can look at hub motors that would have the lower torque available but they don't get the benefit of being in the drivetrain to use the derailleur. They have a fixed internal gear and it may not suite the terrain you ride. I ride 60nm bike so I know the benefit of a lower torque motor.
You may already know all this...