Rear derailleur - can I get away with it?

terongi
terongi Posts: 318
edited June 2007 in Workshop
I am changing over from 12-23 cassette to 13-28 on road bike for ride in the Pyrenees.

I currently have short cage Campag Xenon derailleur.

Standard advice tells me I need medium/long cage derailleur for sprocket with more than 26 teeth.

But what happens if I fit 13-28 cassette and leave short cage mech on the back?

Can I get away with it?

I will probably switch back to 12-23 after my trip, so I would rather not fork out extra œ50 for a new rear mech just for a few days. New cassette is only about œ20-25.

Comments

  • rustychisel
    rustychisel Posts: 3,444
    You'll probably get away with, ifffffff you avoid big-big combination. Depending on the frame and the amount of B adjustment (fore and aft on the derailleur) it should sit okay under a 28T.

    But really, you have to try it and see how the bits mate together. You're going into un known territory with your particular bike

    - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    I'm only escaping to here because the office is having a conniption
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    I\'m only escaping to here because the office is having a conniption
  • monty_dogcp
    monty_dogcp Posts: 382
    Many people run a 29 tooth cassette on Campag short arm mech with few problems - as said, avoid the big chainring when in a large sprocket
  • pbiggs
    pbiggs Posts: 9,232
    The specification seems to change from year to year. 2002 catalogue says max is 29t for Xenon short cage, 2004 says 26t.

    Anyway, have the chain just long enough for the big-big combination - even though you won't actually be using this combination.

    <i>~Pete</i>
    <i>~Pete</i>
  • Pirahna
    Pirahna Posts: 1,315
    Previous threads on here have said that using a 29 with a short cage on a 10 speed setup is OK. I hops so as I'm just about to order one.
  • terongi
    terongi Posts: 318
    <blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Pirahna</i>

    Previous threads on here have said that using a 29 with a short cage on a 10 speed setup is OK. I hops so as I'm just about to order one.
    <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

    Mine is 9 speed. Does that make any difference?
  • pbiggs
    pbiggs Posts: 9,232
    ....No.
    <i>~Pete</i>
  • moorjohn
    moorjohn Posts: 89
    Can I run an old (6-speed) chain with a modern 9/10 rear mech (and friction shifters)? My old suntour xt is getting a bit cranky and irritable. I fancy a shiny new 105, or maybe something Italian...
  • moorjohn
    moorjohn Posts: 89
    ... sadly more for use in the Chilterns than the Pyrenees...
  • moorjohn
    moorjohn Posts: 89
    found my answer courtesy of Chris Juden on ctc website:

    "It is possible to cram sprockets closer together only by slimming down the chain. This has been accomplished mainly by reducing the amount by which the rivet pins protrude from the link plates, thus 8-speed chain also works fine on 7-speed, 6-speed and 5-speed systems. With the development of 9 and now 10-speed cassettes it was necessary also to reduce tooth thickness, so 9 and 10-speed chains are incompatible with other systems. Exceptions to this rule are that Shimano 9-speed rear mechs will also accept 8-speed chain - so they can be used on any system with fewer rear sprockets - and that Campag "C9" chain will also run on Campag 8-speed sprockets, allowing a Campag 9-speed rear mech to be used."

    9-speed 105 it is then. No Campy (sob)

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