Hi
Just did mine in 10 minutes, no removal of anything and wow what a difference. Be sure not to over do it I would do half a turn of the allen key (clockwise) at a time after loosening the lock nut. Be carefull not to move the allen bolt as you undo the main nut as you will loose the point of reference..
It's a tight squeeze and if you are in any doubt let someone who's done it before do it....
Good luck..