it shouldn't cause any probs but do the first cut off with a dremel cutoff whell and then use a nice fine flat needle file to bring it flush to the back of the crank. if you are just shortening the shaft you should have no probs either but use that method and make sure you have a nut on the threads below the cut off area and then take it off it will clean up the end of shaft where you cut it and make for a easy take apart when its needed