rear gear wont keep straight


Active Member
Apr 4, 2016
chain keeps falling off. I've looked at all the forums and i know it has been discused. I know i need to get the rear gear on perfect in parallel to the single speed one on the other side and in parallax to the engine. I know all of this from practice and time put in from my many builds and never wanted to go back to a spoke mounted gear again but my customer is super mad at me because the bike breaks every ride we go on. either the right side chain falls off or the left side does.

so heres what happened.
The right side streched on my single speed coaster brake bike and kept coming off because it was too loose so i removed a link from both sides then adjusted the dropouts.
then i couldnt go more than 2 feet just rolling the bike without the left side pulling off. It was too tight and just slightly off.
like milimeters off! Then i was like f*** this after working on it all day and the customer calling every 5 minutes to ask if it was ready and stating "I want my money back" all day in 95 degree weather and just put it back to the way i found it. Now the left and right side fall off and i cant keep them on to save my f***ing life!

I really need help I have until 3pm tomorrow to fix this and im so tired and i hurt everywhere i just want it to be done.
motorized bicycles used to be fun!


Well-Known Member
May 26, 2008
Chains don't stretch they wear from a lot of use. Tight chain means too damn tight, out of adjustment or needs a link added. Sprockets if lined up properly and at 180deg you should have no issues. To me proper chain tension is a 1/2 to 1in movement up and down on the bottom of it. Is the motor/tranny sprocket lined up correctly, straight and parallel? It's not rocket science to figure it out. Take a deep breath and start off fresh to evaluate it. Seems to me the chains too tight and something is not aligned properly. Eye ball it from the rear holding the rear of the bike up so you can see the chain travel all the way to the front. Are both axle nuts centered on each side the same? Take pics and post them from every angle. A lot of people here to help you.