Problem: Chain comes off sprocket

Hello all,

I just completed my second build, a 26 inch beach cruiser w/ 80cc engine. Everything came together great but I had the same problem I had before, the chain keeps coming off the sprocket onto the spoke side. I looked closely and it appears that it starts to come off from the bottom and then works its way all the off quickly. Its also a real pain because I have to thread the chain out of the spokes. Everything looks pretty good in terms of alignment and chain tension to (a little loose but not much).

Last time I took my bike to this guy in San Diego and he fixed the problem. I believe that he fixed my issue by putting a 50 or 52 tooth sprocket onto the wheel. I could be wrong though because he had it already to go when I came by his house. I might just take that sprocket off and place it on the new bike. ****, I might just take off the whole wheel and put it on the new bike. My issue w/ that is that the new bike is 7 speed, old bike is single speed. New bike also has sweet red rims

Would a sprocket w/ more teeth help my problem? Any other suggestions?

Thanks a ton guys.

Thanks Tom. I think you are right on. I'll cut a few links out of chain (to get that tension you spoke of) and then I'll see if everything lines up. If so, I'll give it a go and let you know what happens