Ok, I just upgraded my old bike. I had the frame rear triangle widened (to 130mm). I put on an a new wheel with an 8-speed cassette hub. I also replace my inner chain-ring (shimano ultegra) from a worn 42 to a new 39 (I kept the big 53 ring). I replaced my old ultegra rear with a new 105 rear derailler. Seems to work fine with a minor nuisance: Using the small chainring with a rear cog gear between the bottom and 3 cogs from the bottom, the chain rubs on the large chainring on the bottom of the chainring. I brought the rear wheel back as much as possible to avoid to reduce the angle. I'm wondering if the problem would be reduced with a 42 inner chainring? Trying to see if the large chainring is warped, but hard to tell. Is this just unavoidable with the new wider cassettes, creating larger angles on tighter frames?