Can I Modify My Cassette or Do I Need to Buy a New One?

phearnde
phearnde Posts: 73
edited January 2009 in Workshop
My cassette is a Shimano Tiagra 12/25 9s, I think I could do with a lower gear as I'm struggling up the hills. Apart from just getting fitter, is it possible to change the 25 tooth cog for a 27 on my existing cassette or do I have to buy a new cassette?

Comments

  • redvee
    redvee Posts: 11,922
    You might find somebody with a casette that they have hacked about and have spare sprockets lying about but the easiest and quickest way is a new cassette.
    I've added a signature to prove it is still possible.
  • maddog 2
    maddog 2 Posts: 8,114
    if it has separate sprockets then yes you can, although the shifting pattern is not always identical, especially if you use a 27t mtb sprocket, so the last shift may be a bit clunky.

    I did something similar for the Fred Whitton - fitted a bail out gear to a road cassette to get over Hard Knott pass.

    I suspect you be better off with a 12-27. Only the last two sprockets are different to a 12-25. The former goes 24,27 and the latter goes 23,25. All the other sprockets are the same.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • El Gordo
    El Gordo Posts: 394
    I think Shimano cassettes are all held together with three allen bolts so the sprockets are easily seperated. Even if it's riveted you can just drill them out.

    But.. can you buy cheap individual sprockets anyway? Cassettes are pretty cheap so I'd be inclined to jsut get a new cassette but hang on to the old one so you have some spare sprockets to replace the middle cogs which invariably wear out first.

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