Chain Keeps Coming Off

I have an old style exercise bike, (just like a regular bike that has brakes to provide resistance
on the front wheel.) that I have used about 5 days a week with no problems for about 2 years. Two
days ago the chain came off, I cleaned it some and oiled it some. It came off again yesterday, and I
used the adjustment on the front wheel to tighten the chain, and it came off again. (On the second
occasion, there was very little play in the chain, but it still came off.) What happens is that I
ride it about 30 seconds, I hear a little grinding noise, and it pops off. Any assistance in fixing
the cycle would be greatly appreciated.

Thanks,

JD

PS I don't see any visible screws or easy way to take off the foot pedals. I am assuming that they
somehow pop off. It would also be useful to take the pedals off because there is a plastic guard
by the chain, that makes it somewhat inconvenient to get to the chain.

 

Decij wrote:

> I have an old style exercise bike, (just like a regular bike that has brakes to provide
> resistance on the front wheel.) that I have used about 5 days a week with no problems for
> about 2 years. Two days ago the chain came off, I cleaned it some and oiled it some. It came
> off again yesterday, and I used the adjustment on the front wheel to tighten the chain, and
> it came off again. (On the second occasion, there was very little play in the chain, but it
> still came off.) What happens is that I ride it about 30 seconds, I hear a little grinding
> noise, and it pops off. Any assistance in fixing the cycle would be greatly appreciated.
>
>Thanks,
>
>JD
>
>PS I don't see any visible screws or easy way to take off the foot pedals. I am assuming that they
> somehow pop off. It would also be useful to take the pedals off because there is a plastic
> guard by the chain, that makes it somewhat inconvenient to get to the chain.
>
>
Unless the gears are recently damaged from some type of impact (seriously bent or missing teeth),
or something physically interfering with the chain, I'd guess the chain and/or gears are worn to
the point where the chain is slipping. Check out chain-wear at one of Sheldon Brown's many
informative pages:

http://www.sheldonbrown.com/chains.html