Derail chain from sprocket and chainwheel	Pull chain tight around bottom bracket shell

Here’s one for fixed wheel road riders who may not have a chain whip in the tool box. (Trackies, of course, have one as a matter of course.)

The idea is to use the bike’s chain itself as the removal tool, but in a more considered, purposeful and effective way than simply sitting on the bike and trying to pedal backwards. It assumes that any lockring has been removed; who uses one anyway?

Address the machine anyway you like, but one way is to remove the front wheel and rest the bike on fork dropouts and brake levers. Unless you can find soft ground, rest the levers on a piece of cloth or paper to avoid scratching them.

Wrap chain around sprocket	Closer pic of chain wrap

Slacken the wheelnuts and derail the chain. With this way of working on the bike, the chain will hang below the bracket shell. Now, if you are removing the sprocket, pull the ‘top’ run of the chain under the bottom of the sprocket, keeping it engaged with the teeth. Turn the wheel in the normal direction of riding rotation, making sure the lower run of chain rests squarely on the piece of chain now engaged with the sprocket. This is vital; if the chain falls off the side during the removal manoeuvre, it may get bent.

As the slack in the chain is taken up, align it so that the free end comes up against the face of the bracket shell further away from the rear wheel. Now, as the wheel is turned, the chain will tighten against the sprocket and lock itself around it as illustrated. Keep turning the wheel and the sprocket will come loose. Voila!

Obviously, the same technique can be used to pre-tighten lightly the sprocket prior to riding by simply reversing the way the chain is wound onto the sprocket. This should be done as a matter of course to avoid any chance of stripping the thread.