Will a 12-30t cassette need a rear mech change?

Foulplay Posts: 7
edited March 2013 in Workshop
Hi all,

I'm looking at options for putting a lower gearing on my 2012 Wilier Izoard XP with Campag Centaur and compact chainset... I found a 12-30T cassette which should give me what I need to comfortably manage the Gavia/Stelvio in September, but would very much appreciate some advice on whether or not it's as straightforward as just swapping the cassette and chain over, or if I'll need to make any changes to the rear mech also?



  • dennisn
    dennisn Posts: 10,601
    Don't know if your Campy rear D will handle a 30 tooth. Some bikes rear D hangers have a greater vertical distance between the axle centerline and the hanger hole and can handle a tooth or two more than a bike with less distance. Hard to say in your case. Try it. If it goes you're good. Just make sure the cassette doesn't hit the derailleur pulley("B" screw).

    Another option might be to buy a 33 tooth front chainring from TA Specialties. That's assuming you're running a 34 on the front now. It's not a big deal but every little bit helps.
  • Monty Dog
    Monty Dog Posts: 20,614
    A regular short cage rear mech will handle 29t, so you may be able to get away with a 30 - it may be close because of things like the length of your frame rear mech hanger.
    Make mine an Italian, with Campagnolo on the side..
  • Foulplay
    Foulplay Posts: 7
    Thanks gents. Very much appreciated... The 30t cassette that I saw was being sold as a Campag Centaur, which kind of indicates it should work with the existing mech, but as we all know, it's never quite so straightforward as that.