Was hoping someone out there might know what to do about a rear wheel slipping in the dropouts.
I just recently built a classic steel bike. The frame is a Concorde with chromed dropouts. 130mm spacing, Shimano 105 kit. Planning on using it this winter/spring as my beater bike. However, the last two times I tried to ride the bike, the rear wheel would slip out of the dropouts any time I apply any power to the pedals. What happens is the wheel slides to the left (the cassette is pulled forward by the chain), which leads me to believe it's a derailleur issue (I have tightened the skewer appropriately, and tried two different wheels). So the left side of the wheel goes against the horizontal chain stay on the left side and I have to stop and re-center the wheel.
It occurred to me that the B-tension adjustment screw might be the issue, so I checked it and it seemed like the screw wasn't in the right spot. But to put it in the right spot (following the Shimano directions), I needed to back it out, almost to the point that it would unthread from the derailleur. This would bring the top jockey wheel close to the cassette.
I haven't had a chance to test whether this adjustment worked, but I'm inclined to say it did not.
Anyone out there have a similar issue? What was the solution?