COMMUNITY : FORUMS : SPORTS

Most of the single-to-multiple speed conversions I found on the Web involve changing out the rear hub for a multispeed hub. It sounds like you don't want to (or can't) do that because of the electric motor. I can't see any reason why that's necessary, though. Here's what I would do:

First, replace your crankset with a 3-speed crankset (that's your Google or Amazon search term) and the associated shifting hardware.

You will also need to mount a chain tensioner at the rear hub, since the three gears require different chain lengths. The tensioner should just mount to the frame behind the hub, and not require any wheel modifications.

If you've got a true fixed gear (pedals must turn if the wheel turns) I can't help--but if it is a single speed freewheel, there used to be a BMX setup that would work. Single rear freewheel, chain tensioner (basically a rear derailleur but locked in one gear) and a standard front derailleur. The BMX ones used a brake lever for shifting-you would hold the lever for low gear, release it for high.

I have no idea how to do that, but I *know* it would be a popular build if you managed it - a geared electric bicycle would be very useful here in San Francisco.