Cassettes 11-28 or 11-30

Rouge Penguin
Rouge Penguin Posts: 347
edited June 2014 in Workshop
Hi All,

Sold my old bike to a colleague and he's decided to get a bit more adventurous on it. He lives over towards the Chilterns and is struggling with the current Std chainset and rear 12-25 on some of the hills.

Ive spotted a couple of 11-28 or 11-30's cassettes on t'web. Pretty sure the 11-28 will fit fine, but will the 11-30 be a bit tight?

Or is he maybe better off changing to a compact chainset and leaving the rest?

Cheers for your thoughts....

Ian

Comments

  • zx6man
    zx6man Posts: 1,092
    depends on what the rear mech can handle.
  • DiscoBoy
    DiscoBoy Posts: 905
    If, as you say, an 11-28 is compatible, I would start with that.

    This is because a new chainset is considerably more expensive than a new cassette. And 39-28 is only 0.8 gear inches longer than 34-25.
    Red bikes are the fastest.
  • markhewitt1978
    markhewitt1978 Posts: 7,614
    Remember he'll probably need a longer chain too.
  • drlodge
    drlodge Posts: 4,826
    If the OP is moving from 39x53 & 12-25 to 39x53 & 11-28 he'll possibly need to shorten the chain, depends how the length was setup originally (e.g. setup on big-big, or small-small as I would do).
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  • Rouge Penguin
    Rouge Penguin Posts: 347
    Cheers all,

    Either way i'll be fitting a new chain as it did a fair few miles as my commuter. Pretty sure he wont need 11-30, theres nothing that harsh this side of oxford (Wycombe, Henley, Chistmas common etc) that he cant conquer with a few miles training.
  • Pokerface
    Pokerface Posts: 7,960
    drlodge wrote:
    If the OP is moving from 39x53 & 12-25 to 39x53 & 11-28 he'll possibly need to shorten the chain, depends how the length was setup originally (e.g. setup on big-big, or small-small as I would do).


    You definitely would NOT need to shorten the chain. (I assume you're referring to the difference in length from 39-11 to 39-12?) Besides the fact you shouldn't be riding in that gear, the 1T difference won't be noticeable in the chain length. However the difference that going from a 25 to 28 presents may require a longer chain.

    Personally I run everything from 26T to 32T cassettes on my bike and manage to do so without altering the chain length.
  • taon24
    taon24 Posts: 185
    My understanding is that a correct length chain is only vital to prevent damage when cross chaining badly as long as it is close to correct length. Too many links will cause the chain to rub against chain when using very few teeth, while too few links will cause the derailleur to straighten and possibly break when using maximum teeth.
    If you use the bottom 7 gears of a 11-28 with a compact it will be 14+34= 48 teeth minimum. the maximum will be 50+19 = 69 tooth maximum using the 7 smallest sprockets with the big ring. the 21 tooth gap will easily handled by a short cage dérailleur with the links approximately correct.
    Clearly if you completely cross chain the 50+28 = 78, While 34+11 = 45, which gives a much bigger 33 tooth gap, which probably requires a longer cage derailleur and a correct chain length to prevent damage

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