Anyone ever tried a manual hub transmission?

Jan 21, 2015
Portland, Oregon
So I was thinking it might be possible to convert my bike from having 2 gears in the front over to just one gear, then I could steal the front derailleur, modify it, and put it onto the motor chain and add a 46t sprocket next to my 36t on the rear hub, then fashion some sort of spring loaded chain tensioner to take up the slack, and then I could have a two speed manual transmission to go with my new engine upgrade! Has anyone ever attempted to do this, and what were your results, also what are other's thoughts on this idea?


Staff member
Sep 15, 2008
Littleton, Colorado
I did some experimentation with a two-sprocket system a few years back. I wasn't trying to have a shifting system but was only looking at having the option to run either a 48T or a 36T rear sprocket. Chain/sprocket misalignment problems were the result. Seperating the two rear sprockets enough for chain clearance resulted in the chain not tracking correctly to either one.

You can get away with the misalignment on the pedal side chain but the engine drive chain needs to be aligned with the sprocket and not off-set to either side. I'm also not a fan of spring loaded chain tensioners.

Not saying it can't be done just telling you what I ran into. Good luck if you try it.



Active Member
Jul 29, 2012
Central Illinois
Yes. I admire the creative thought, too.

But getting it right is going to be tricky. And I do wonder if you're going to be able to bump-start your bike with a spring chain tensioner.


Well-Known Member
Nov 28, 2012
sf bay area
Chain alignment will be the killer. I've had chain about 1/4" out of alignment but it was about 6" farther from the wheel than yours will be.

Also chain slack will get you. Chains don't like huge jumps but small jumps are OK.

Modifying a derailleur made for bicycles to use on a motor chain is a bad idea. The heavier use, much larger chain slack, and higher chain speeds will make short work of one. It would be better to design your own based on an existing design.

If you still want two sprockets on the back like this, I suggest you go with v-belts. It would be easier to custom make a derailleur and you wouldn't need to worry so much about alignment. Running machinery with v-belts, I was able to roll the tensioned belt over with my fingers to the next speed with usually minimal effort. But then with belts, spacing becomes a problem. Two v-belts side by side take up as much room as a 9-speed cassette. Good luck!