Downtube Shifter Bracket Slipping
I recently refurbished a bike set up with Campy nuovo record shifters on the downtube. It included removing and polishing the shifter bracket and paint underneath. After a couple of rides I find the shifters are going out of adjustment and the cables are going slack from the bracket slipping down the tube. I can even see an outline of the bracket in the paint that is slightly less sun faded telling me the bracket has slipped yet again! I tried the obvious: tightening the bolt and nut VERY TIGHT but still having the problem. I don't want to shear the bolt off. Anybody got a solution without drilling holes in the down tube?