Is there any reason why I can't use a Ultegra 6603 (10spd) with an old 7spd setup? Is the cage too narrow for the 7spd chain? I'm thinking of swapping my RSX groupset over to a different frame which needs a braze-on front mech. Its only a tenner for the Ultegra in the Chain Reaction sale which seems far more reasonable than £17 for a bottom of the range 2300.