maybe a dumbass question but will a 9 spd rear mech work fine with a 8spd road cassette and 8 spd stx rc shifters??? they use the same freehub for both 8 and 9 spd so the total distance travelled by the mech is the same, so why are the mechs defined as either 8 spd or 9 spd, not both??? I cant get mine to set up correct. surely the only problem wud be if i was using 9 spd shifters with 8 spd cassette n mech???? cheers all