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Changing cassette - will it throw out the indexing?

themightywthemightyw Posts: 409
edited April 2016 in Road general
Hi

I'm considering switching from an 11-25 cassette to an 11-28 cassette. Do you know if I'll need to re-index my rear derailleur or should I be able to swap it out directly? Many thanks in advance for the advice.

TMW

Posts

  • fenixfenix Posts: 5,437
    It shouldn't but it might.

    Don't let it put you off though. If you need the 28 it's a tiny job to re index if at all.
  • Sirius631Sirius631 Posts: 1,015
    The indexing shouldn't be affected; after all, the cassettes are designed so that the sprockets are spaced at known locations away from the contact surface between the cassette body and the hub. You should be able to change between cassettes of the same manufacturer with impunity.

    Answer this: do professional riders have to re-index when they have a rear wheel change? If you're not sure, the answer is no.

    One thing I would keep an eye on, though, is whether you have enough chain capacity when you've added an extra three teeth. You don't want to mistakenly change to the big ring whilst on the big sprocket and drag your rear mech into your spokes due to the chain being too short.

    Riding a bike means being able to undertake regular maintenance. You should get to know how to disassemble and reassemble your bike, including re-indexing the drivetrain.
    To err is human, but to make a real balls up takes a super computer.
  • singletonsingleton Posts: 1,688
    It shouldn't.
    I've done this a couple of times and it's usually fine.
  • debelidebeli Posts: 582
    I've never known it to do so.

    Which is not to say it won't, but I'm not quite sure how it would.

    Indexing and sprocket size are variables whose effects are on perpendicular planes.

    You will be fine.
  • darkhairedlorddarkhairedlord Posts: 6,478
    probably takes longer to ask on the forum than re-index.
  • darkhairedlorddarkhairedlord Posts: 6,478
    Sirius631 wrote:

    Answer this: do professional riders have to re-index when they have a rear wheel change? .
    of course they do, that's why the mechanic hangs out of the window re-trimming the rear derailleur, isn't it?
  • veronese68veronese68 Posts: 23,475 Lives Here
    Sirius631 wrote:

    Answer this: do professional riders have to re-index when they have a rear wheel change? .
    of course they do, that's why the mechanic hangs out of the window re-trimming the rear derailleur, isn't it?
    I thought it was to give them a push so they could catch up again. :wink:
  • themightywthemightyw Posts: 409
    Thank you everyone :)
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