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Long or Medium cage rear derailleur shall i choose??

buzzme84buzzme84 Posts: 16
edited November 2014 in Workshop
Hi,

i had a crankset 53 - 42 - 30 teeth.
and willing to have a 11 - 25 teeth cassette.

base on the calculation of the chain wrap (53-30) + (25-11) = 37 total capacity

For Campagnolo chart:
Short - Maximum Cassette Cog is 26 and Total Capacity is 27
Medium - Maximum Cassette Cog is 29 and Total Capacity is 36
Long - Maximum Cassette Cog is 29 and Total Capacity is 39

my question are:
1. can i use medium cage on 37 capacity chain wrap which is 1 unit difference?
2. can i choose a over large long cage? will it have any issue with 2 units differences?
3. or shall i need to change my cassette to 12 - 25 which giving 36 in total capacity to fit the medium cage?

or any better suggestion without changing crankset.

thank you.

Posts

  • keezxkeezx Posts: 1,316
    1-Certainly no problem, I've used that (12-26) even with a short derailleur.
    2-Long cage can, but isn't necessary.
    3-No need to change, but do you use the 11? If no, drop it and get a useful cog instead.

    Alltogether is buying a medium derailleur the best option which can take almost anything.
    A short derailleur can do this, but requires more thinking during shifting (no 53x26 or 30x12)
  • lesfirthlesfirth Posts: 1,203
    Chain wrap or lack of it is not a problem. I run a 12- 29 cassette and 50-39-28 chain rings with a centaur short cage rear mech. Chain is as short as it can be without causing a problem just in case I inadvertently cross chain into big big . I only use the small chain ring with the 3 or 4 biggest rear sprockets. If I inadvertently use smaller sprockets I have a drooping chain. I have used this without a problem for a few thousand miles.
    Before you ask I am, as someone on this forum depressingly put it, in my twilight years and I ride mostly in the Pennines.
  • pinnopinno Posts: 42,682
    lesfirth wrote:
    Chain wrap or lack of it is not a problem. I run a 12- 29 cassette and 50-39-28 chain rings with a centaur short cage rear mech. Chain is as short as it can be without causing a problem just in case I inadvertently cross chain into big big . I only use the small chain ring with the 3 or 4 biggest rear sprockets. If I inadvertently use smaller sprockets I have a drooping chain. I have used this without a problem for a few thousand miles.
    Before you ask I am, as someone on this forum depressingly put it, in my twilight years and I ride mostly in the Pennines.

    What yer sayin' like? Is the OP supposed to get a rear mech to accommodate a 28 front, 32 rear granny gear in preparation for his future retirement in say the Peak district? :wink:

    It's a funny thing. In all my years of cycling, I have never calculated how much chain I need. I have just reduced the number of links in a new chain until it looks right.
    seanoconn - gruagach craic!
  • Keezx wrote:
    1-Certainly no problem, I've used that (12-26) even with a short derailleur.
    2-Long cage can, but isn't necessary.
    3-No need to change, but do you use the 11? If no, drop it and get a useful cog instead.

    Alltogether is buying a medium derailleur the best option which can take almost anything.
    A short derailleur can do this, but requires more thinking during shifting (no 53x26 or 30x12)

    thank you for you kind answer, i will go for medium cage which look nicer XD
  • lesfirth wrote:
    Chain wrap or lack of it is not a problem. I run a 12- 29 cassette and 50-39-28 chain rings with a centaur short cage rear mech. Chain is as short as it can be without causing a problem just in case I inadvertently cross chain into big big . I only use the small chain ring with the 3 or 4 biggest rear sprockets. If I inadvertently use smaller sprockets I have a drooping chain. I have used this without a problem for a few thousand miles.
    Before you ask I am, as someone on this forum depressingly put it, in my twilight years and I ride mostly in the Pennines.

    wow... any reason why not go for medium cage or suitable cage to solve the problem?
    any advantages on short cage?
  • keezxkeezx Posts: 1,316
    The advantage of a short cage could be that you own aready one......
  • keezxkeezx Posts: 1,316

    It's a funny thing. In all my years of cycling, I have never calculated how much chain I need. I have just reduced the number of links in a new chain until it looks right.

    Modern times.
    Paople believe some figures on a screen are better then 30 years expierience....
  • lesfirthlesfirth Posts: 1,203
    Keezx wrote:
    The advantage of a short cage could be that you own aready one......

    Correct! I had one. I needed lower gears than I had with a compact chainsets so I tried a triple . It worked without a problem so it stayed on the bike.

    My point to the OP was that in practice you do not need a rear mech. that will take up the full chain wrap.
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