Cassette change 25 - 28

kayo74
kayo74 Posts: 299
edited May 2013 in Road general
Looking at changing rear cassette from 25 to 28 would I need to change the length of chain or adjust anything else?. Ultegra full spec on bike present.

Cheers

Comments

  • diy
    diy Posts: 6,473
    Yes you will. TBH if you are changing cassette you may as well get a new chain too, since you can often get a bundle deal.

    However, the bigger issue is if your mech has the capacity for the 28. If you currently use say a 25-12 and are going to a 28-11 you may not have sufficient capacity in the mech.

    You need to check the capacity of the mech and calculate if you can do it using this:

    http://home.earthlink.net/~mike.sherman/shift.html
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  • shmooster
    shmooster Posts: 335
    Recent Ultegra short cage derailleurs have no problem dealing with a 28 rear cassette. Older ones might be different.

    If you go above 28 you need to switch to a long cage.

    http://www.shimano.com/publish/content/ ... ype-..html
  • CiB
    CiB Posts: 6,098
    I swapped from an 11-25 to 11-28 Ultegra with no issues whatsoever.
  • Anonymous
    Anonymous Posts: 79,667
    Am about to try an 11-28 instead of current 12-25 with my Dura Ace derailleur.

    The bike was originally a double but changed at point of sale to a compact (50/34). LBS said that chain was fine and they did not remove any links, so am guessing chain will be fine.

    What do I need to look out for to see if derailleur can cope with the 11-28 when I try it out?

    Friend put an 11-28 on his Ultegra and its been fine.
  • CiB
    CiB Posts: 6,098
    With the chain on its shortest path - so 11/34 - check the the chain still passes freely without rubbing against itself or the mech. If there's too much slack the mech will allow the lower jockey wheel to spring back up far enough that it doesn't hold the chain clear of the rest of the mech.

    Similarly on the longest path 28-50 the lower jockey wheel can be pulled so far forward that chain isn't held round enough teeth on the cassette and that changes don't happen properly. That's more of a judgement call.
  • Bar Shaker
    Bar Shaker Posts: 2,313
    I did this on my last two bikes with no problems at all.
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  • Critch
    Critch Posts: 60
    Went from 11 - 25 to 11 -28 no changes needed at all. Im using an Ultegra 12 - 32 right now though.

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