Hi! I have an old Raleigh road bike that came with friction stem shifters. I was thinking of replacing them with a clamp on downtube shifter, a ratcheting model I like. I put it in place to make sure that it fit the tube okay, but I noticed that the cables would be a few mm farther away from the downtube than the narrow path from the old cable stops. Just about 3 mm farther from the tube on either side.
Would 3 or 4 mm change in the lateral position of the shifter cables at the top of the downtube make a serious difference in performance? Would I have to get a different cable guide for the bottom of the bottom bracket? Thanks.