Originally Posted by
OldCoot
I agree that respacing the rear will do little, but it should help make things run better once the issue is resolved.
Hadn't thought about a washer, good idea. Typically one on each side? How thick?
Also your point about rubbing on the inside, would rule out a larger cog as a solution, though I understood the OP to say on top. Again a photo would be helpful.
As I recall these Supercourse came in a beautiful green.
[MENTION=19743]USAZorro[/MENTION] nailed it. On a freewheel system, the hub bearings on the drive side are significantly inboard from the dropout, and there's significant stress on the axle. Modern cassette type hubs essentially eliminate that issue - the hub bearings are out near the dropout.
So if you're running a freewheel system, you can optimize it by making the axle locknut just clear the freewheel enough so the chain doesn't hit the chainstays. You do this with spacers. I recently modified a Campy high flange rear hub to fit a 7 speed freewheel, swapping out the axle for a slightly longer one.
Any futzing around with axle spacers will require a bit of redishing of your rear wheel to keep it centered on the frame, as noted by others, above.