Hi
Perhaps the rear derailler is out of alignment or bent. Had similar problem. I took it to a LBS and they aligned the RD and cured the problem. The bike fell down on the RD side a few times over the years which accounted for the misalignment.
John Hawrylak
Woodstown NJ
> Hi All,
>
> I've just rebuilt my recently-acquired Claud Butler,
> 'Electron' Super Five model. It's a lovely, smooth ride, too.
> The problem is that when I change gear, the chain also
> derails off the chainwheel, almost every time. Yes, I can
> reach down and lift it back on, but that's a bit dangerous
> in traffic. It's when changing to a higher gear only, I can
> look down to watch the process, and see the nice, smooth
> change at the back as the chain flicks across to the next
> smaller sprocket, and then watch the 'wave' in the chain
> travel along to the chainwheel, and presto! off again.
>
> I should mention that the chain is a new Sram PC 38,
> a low budget chain, sure, but my other bikes with this chain
> don't misbehave in this fashion.
>
> I know that some other bikes had this problem in the past,
> and one cure was to fit a front der. mech. as a 'chain keeper'
> for the single chainwheel. I'm not sure I want to do that.
>
> The bike had been fitted, at some time,
> with a six-speed cluster, which
> required two heavy washers to be added on the axle to
> allow the chain to clear the stay. That left only two or
> three threads for the R/H axle nut. Luckily, I've managed
> to recover the threads, and adjust accordingly. That plus
> the derailleur was bolted hard on the hanger, so it couldn't
> pivot. Aaarrrggghhh!!! There's a used Suntour five-speed cluster
> on now, a good one.
>
> The chainwheel looks good, i.e., not worn out.
> The chainline, well I think it's a straight line when on 2 nd gear.
> And I swear there's only 20 to 25 thou" between the R/H crank
> arm and the chain, when in top gear. The cotter pins don't allow
> for any lateral adjustment :-(
>
> I can't help feeling that this frame was originally meant to take
> a gear hub, i.e. a single chainline, and that the derailleur was
> added perhaps to fill a gap in the model range.
>
> Any suggestions will be much appreciated.
>
> Paul Aslanides.
> Ferntree Gully.
> Melbourne.