Tiagra GS cage rear mech and 32T cassette.

jimsam33
jimsam33 Posts: 59
edited February 2010 in Workshop
Hi,
I have just bought a new bike from a local bike shop and wanted a set-up that would help me up those hills.

My set-up is (how it came out of the shop) is 9 speed shimano 50/34 on the front and 11/32 on the rear.

The rear mech is a GS Tiagra road. Shimano state that the maximum cassette size for this is 27T. The total capacity for the mech is 37T which fits okay.

My question is:

Will this be okay? or will it have some lasting problem.

I have been out on the bike for a couple of decent rides (30miles and 20miles) and had obsolutely no problems; the rides involved trying out all the gears (including small/small and large/large to see if they worked)

Should I consider changing the rear mech for a MTB one or just leave it as the shop mechanic set it up.

Would really like some thoughts from you guys.

Comments

  • Monty Dog
    Monty Dog Posts: 20,614
    As long as the top jockey wheel doesn't hit the big sprocket then you should be OK
    Make mine an Italian, with Campagnolo on the side..
  • jimsam33
    jimsam33 Posts: 59
    There seems to be plenty of clearance.

    Everywhere you read though, people state that the largest you can go is 28T.

    Just a little bit concerning, especially when Shimano state 27T max.
  • John.T
    John.T Posts: 3,698
    Shimano are being conservative with their recomendations but there are other factors that can affect how big you can go. Not all mech hangers are the same length and if your bike has a slightly longer than average one then you will be OK.
    My Fleet.
  • salsarider79
    salsarider79 Posts: 828
    TBH (I'm a bike shop mechanic) I would have fitted a long cage rear mech. However if all the gears work then it'll be fine. If you struggle to find a few of the gears, and it's not an adjustment problem, then I would be looking at an MTB rear mech. You say all gears work, so it should be fine.
    I ran the tiny short cage XTR rear mech on my Stumpy FSR with a 11/32 and a 22/32/44 triple (which is designed to run with a small cassette and a double ring not a triple), for a year with no problems.
    jedster wrote:
    Just off to contemplate my own mortality and inevitable descent into decrepedness.
    FCN 3 or 4 on road depending on clothing
    FCN 8 off road because I'm too old to go racing around.
  • John.T
    John.T Posts: 3,698
    TBH (I'm a bike shop mechanic) I would have fitted a long cage rear mech.
    I will give your shop a miss. A GS mech is long cage. :shock: :wink:
    My Fleet.
  • jimsam33
    jimsam33 Posts: 59
    Thanks for the input so far. My understanding is that a GS mech is actually a medium cage (that is sometimes referred to as a long cage on road bikes). A SGS Mech is actually a long cage.

    The shop have offered to change the mech to a MTB SGS one. I think this will be best all round.
  • skyd0g
    skyd0g Posts: 2,540
    You should be okay so long as you avoid extreme combinations of gears (which you should do anyway) such as small/small and large/large combo's.
    Cycling weakly
  • John.T
    John.T Posts: 3,698
    jimsam33 wrote:
    Thanks for the input so far. My understanding is that a GS mech is actually a medium cage (that is sometimes referred to as a long cage on road bikes). A SGS Mech is actually a long cage.

    The shop have offered to change the mech to a MTB SGS one. I think this will be best all round.
    Correct. SS is the normal road short mech and GS is the longer one for a triple. The only difference is a longer cage to take up more chain. It does not have any more clearance between the top jockey and cassette. The jockey does however move through a smaller arc for a given no of teeth and this may affect the clearance. The GS gets called both a long cage and a medium cage, often by the same shop. Just think of it as the longer road one.
    You definately do not need a SGS mech as that is the long cage MTB one with 45 max teeth limit. A GS MTB one with 35 teeth limit will do all you want and more and will look a lot better.
    If your current set up works well as it is and changes cleanly on and off the 32 on both rings I would not bother spending money on a new mech unless you want to go to a 34.
    My Fleet.
  • jimsam33
    jimsam33 Posts: 59
    LBS changed my RD for a Shimano Deore one for a nominal charge (£10), as they had to put another chain on as well. New chain sram pc-971 as opposed to the original shimano hg-53.

    I am comfortable that this mech meets all my needs and is what shimano reccomend aswell. And should I wish to change my gear situation in the future this mech can cope with a 28 - 34 rear and a triple should I ever need to go down that route.

    It may not look as good as the tiagra but this is my second bike, so i'm comfotable with that.
  • maddog 2
    maddog 2 Posts: 8,114
    John has it.

    Any more than 28t normally needs a mtb mech

    it's not about cage length, it's about mech geometry and mtb mechs give more clearance
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer

Categories