Replacing Bosch bottom bracket drive on Yuba Spicy Curry

JackFlorey

100 kW
Joined
Feb 19, 2020
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1,653
Location
San Diego
I came across a used Yuba Spicy Curry for cheap and picked it up. I am in the early stages of modifying it for touring. My first thought is to add a direct drive hub for regen and higher power; the rear wheel is a 20 inch, and would work pretty well with an All-Axle or similar. It currenty has a 250 watt Bosch mid drive.

Question - can you get a "fake" mid drive that just has a bottom bracket, to let me get rid of the weight of the Bosch motor? Or can you hack up a Bosch (removing the motor/controller) so that it is just the bottom bracket?
 
I don't know of a unit built to replace the drive to provide just a BB. AFAIK you'd have to build a shell to hold the BB, that bolts to the frame's housing for the drive.

You could probably remove most of the stuff in the real drive unit to leave just the BB and support mechanics, but how much of it depends on how they designed the version you have. If they did anything silly like embedding the BB shaft in the motor or gearing, you'd have to leave those parts in (or machine / cut those parts off the shaft, and if any supports for the shaft are parts of other things, making replacements as needed to support the shaft).

But...is the drive that heavy or have a negative effect on the pedals, that requires removing it to solve the issue? If it's functional, it might be useful as a backup system. If only the motor is functional, you could drive it from an external controller (like the BBSxx has had done wiht Phaserunners, etc).
 
There's no reason you couldn't, in principle, use the same hardpoints that hold the Bosch drive to mount tubular spacers, and then use those spacers as components of a space frame supporting a conventional BB. You could even change the location of the BB in the process. It would be a significant amount of work, but I do like the idea of throwing Bosch's weaselly garbage out of your bike completely. If I did it, I'd send them a photo of how I improved my bike.
 
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