Equipment needed: Vice, Chain whip, A big long bar of some kind. hollow in the middle. A blow torch.(possibly) Step 1. Clamp crank into vice very tight. Step 2. Wrap chain whip around the cog, (so it will turn in an anti-clockwise rotation) Step 3.This is where the big bar is involved, The middle of the bar needs to be hollow so you can see straight through it, place the bar onto the chain whip, so you get extra lever age. (may come off easier) If it does not work try heating the cog and the crank up. Usually works It will be very hard to get off I guarantee. Hope I have helped. Ross.