Cassette question

chopchopchop
chopchopchop Posts: 98
edited March 2016 in Road general
Hi, I have a 28/12 cassette at the moment. Can I just change it for a 30/12 or will I need to change the chain lenth?

also does changing the cassette need indexing again?
Specialized Roubiax elite
Pinarello Uno
Shwin MTB

http://www.strava.com/athletes/hughes_terry

Comments

  • chris_bass
    chris_bass Posts: 4,913
    You might need to check your rear mech can take a cassette that big.

    you'll probably be ok with chain length, it'll only affect the extreme cross chaining which is bad anyway!

    you will need to re-index the gears.
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  • Bobbinogs
    Bobbinogs Posts: 4,841
    mmm, I am not convinced with the re-indexing. It might need the odd tweak (half a twist either way on the barrel adjuster) but the cogs are staying in the same place so it should be ok.

    OP, you will probably need to adjust the B-Stop (as in, wind it down to its minimum setting without the screw actually dropping out). Basically this adjusts the clearance between the biggest cog and the guide jockey wheel.

    As above, you should be ok with chain length but you may not be depending on where you are with it at the moment. Don't forget that Shimano pins are not reusable nowadays so use a KMC Missing Link (and any old inner link lying around) to add length.
  • markhewitt1978
    markhewitt1978 Posts: 7,614
    chopchopchop wrote:
    Hi, I have a 28/12 cassette at the moment. Can I just change it for a 30/12 or will I need to change the chain lenth?

    also does changing the cassette need indexing again?

    As with many things it depends. You probably won't need a longer chain unless your current chain was already on the margins. You probably won't need to reindex unless your B screw was already on the margins.

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