I've replaced the rear wheel on my bicycle. The new wheel is different in two respects:
- I got a 8-speed freehub because 7-speed freewheel hubs seem to be difficult to find these days.
- I had a 7-speed cassette with 14-28 teeth and replaced it with 12-32, using an extra 12T cog as a spacer on the distal side.
Two problems emerged:
The previous cassette had a lot of space between the smallest cog and the dropouts. Not so with the freehub cassette. I had to put the spacer cog on the distal side rather than the proximal one because otherwise the chain had no clearance when on the smallest cog. Even then the lock ring touched some sort of round screw head used to secure the derailleur. With a wrench, I was able to bend the steel (more exactly, unbend it; without wheel, I measure 133 mm rather than 135 between the drop outs and they still bend a little to the inside in the back) on the drive side and now it doesn't touch anymore. However, the clearance is very small when the QR skewer is tight (less than 1/2 mm). The question is: is it a good idea to file the screw head a bit or bend the drop out more so as to get more clearance? I'm worried that under heavy load the frame will bend in a way that there is contact with the lock ring.
The derailleur can't handle the chain being the two largest cogs. This crossed configuration is not something that I would ever use, at least on purpose. Is there anything I should be concerned about here?