A hair drier won't get hot enough to help, I think. A heat gun might, but I doubt it. Aluminum tends to wick heat away from where you want it quite rapidly. You might try heating the bolt with a small torch, then let it cool before wrenching it. If you can support the frame horizontally with the derailleur boss resting on something substantial, you can whack the bolt a bit to break up the corrosion. PB blaster or Chrysler's rust penetrant (part# 04318039AC) are very helpful. And flammable, so be careful if you use heat after applying. Michael Shiffer EuroMeccanica, Inc. 114 Pearl Street Mount Vernon, NY 10550 (914) 668-1300 euromeccanicany.com