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8 sprockets on a 9 speed?

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  • 08-06-2011 7:57am
    #1
    RichieMag
    Closed Accounts Posts: 7 ✭


    Hi all,

    I need to get a new chain for my Trek 1000SL.

    The rear mech has "Shimano Tiagra 9-Speed" written on it, but I can only count 8 sprockets on the cassette.

    It was bought by my Dad from a local bike shop who tailored it for him, so could they have swopped the cassettes, or am I missing a trick here?

    Basically I need to know whether to get an 8- or 9-speed chain, as well as clear up some major confusion! :confused:


    Thanks!
    Tagged:


Comments

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    #2
    seamus
    Registered Users Posts: 68,317 ✭✭✭✭seamus


    An 8 or 9 speed chain will work fine on an 8 speed cassette, but only a 9-speed chain will work properly on a 9-speed setup as an 8-speed chain will be a little too wide. It looks like this bike comes 8-speed as standard. Theoretically speaking, the "9-speed" badge on the rear mech is just a badge. Mechs aren't indexed, so a "10-speed" mech will work just fine with 8-speed shifters and vice-versa.


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    #3
    Lashed
    Registered Users Posts: 138 ✭✭Lashed


    seamus wrote: »
    An 8 or 9 speed chain will work fine on an 8 speed cassette, but only a 9-speed chain will work properly on a 9-speed setup as an 8-speed chain will be a little too wide.

    Took advice exactly as above and tried a 9 speed chain for an 8 speed cassette. I have the same bike which uses a sram 8 speed cassette.
    The 9 speed chain would not work on the 8 speed cassette.
    The shifting was fine but width was not the problem. The 9sp chain continuously slipped one tooth when pressure was put on it.

    If there are 8 coggs then you have to assume its an 8 speed cassette so buy an 8 speed chain.


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    #4
    seamus
    Registered Users Posts: 68,317 ✭✭✭✭seamus


    Lashed wrote: »
    The shifting was fine but width was not the problem. The 9sp chain continuously slipped one tooth when pressure was put on it.
    This usually indicates an excessively worn cassette rather than anything else, however...
    If there are 8 coggs then you have to assume its an 8 speed cassette so buy an 8 speed chain.
    ...yes, always best to buy the right chain for your setup. No point in fitting a 9-speed chain unless you're in a bind or getting a particularly special deal.


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    #5
    Lashed
    Registered Users Posts: 138 ✭✭Lashed


    seamus wrote: »
    This usually indicates an excessively worn cassette rather than anything else

    I agree there but the cassette seems to have plenty of life left in it. This brings up the question, should you change the cassette with the chain? or what is the life of a cassette in comparison to a chain?

    I have a new ultegra 8sp chain on order from bike24.com so i'll see how that goes.


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    #6
    cython
    Registered Users Posts: 4,766 ✭✭✭cython


    Lashed wrote: »
    I agree there but the cassette seems to have plenty of life left in it. This brings up the question, should you change the cassette with the chain? or what is the life of a cassette in comparison to a chain?

    That question varies a lot depending on the maintenance and cleaning that the bike has seen. If you replace the cassette before the chain is too worn, then it wouldn't be unheard of to get 4+ chains to one cassette. However, if you run a worn chain on a cassette for too long, it will wear larger gaps between the teeth, and a new chain will not mesh properly with the wider spaced teeth, causing slipping such as what you describe. If the chain is let go this far, then the cassette must be replaced with the chain. Sheldon Brown has much to say on the subject.


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