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...for really stuck pedals, I heat the area around the pedal shaft where it goes into the crank arm with a MAPP gas plumber's brazing torch, but you can melt aluminum with one of those, if you get it too hot. Don't melt the aluminum, and if you have some Freeze-Off, do a couple of heating and cooling cycles. Unfortunately, when a pedal is really seized in an aluminum crank arm, sometimes some of the threads come out welded by corrosion to the pedal. But don't worry about it unless it actually happens.
