Does length matter?
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  1. #1
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    Does length matter?

    Derailleur length that is. For example, Ultrega offers rear derailleurs in short and long cage length to accommodate different sizes of cassettes. Other than that, does the cage length make any difference in shifting? Shorter crisper? Longer smoother? No difference?

  2. #2
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    I asked the same question a few years ago and the consensus was; No.

    If you think about that would make sense because all the extra length is added below anything that has anything to do with shifting.

  3. #3
    tlg
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    Quote Originally Posted by ivanthetrble View Post
    Other than that, does the cage length make any difference in shifting? Shorter crisper? Longer smoother? No difference?
    Weight. Shorter has less weight.

    Shorter (theoretically) shifts smoother/crisper. I've never noticed a difference. Modern derailleurs shift so well, you won't notice a difference. And of course, electronic derailleurs makes it irrelevant.

    Longer gives you more range in gears. There's really no reason not to go with a long cage. Unless a few grams matters to you.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  4. #4
    'brifter' is f'ing stupid
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    No...and the post above mine isn't exactly correct. Firstly, the extra cage length has ZERO effect on shifting. The shift takes place the upper pulley, so no difference in any way.

    Secondly the extra length really doesn't have anything to do with larger cogs directly. The ONLY reason for the longer cage is to wrap the extra chain you'll need for larger cogs. That's it. Nothing else. If you take a short cage derailleur(say Max 28t cog) and swap the cage to a longer one you won't have any success clearing bigger cogs (say 34t) because the upper pulley is traveling at the same angle as it moves across the cogs. If you changed the mounting point of the cage you'd gain some clearance which is generally how Shimano does it now. In a way I'm contradicting myself but my point is that the longer (Medium cage, Shimano doesn't make a 'long' cage road derailleur) is only long to wrap chain. In the old days when Shimano made doubles and triples the max cog size you could use was 27t for both derailleurs, the SGS just wrapped the extra chain you'd need for the triple up front than the SS short cage. There is some truth to the notion that the GS won't shift as well as the SS, but only on small cassettes. As the GS positions the upper pulley further away from the axle centerline as you shift to larger cogs the space between the upper pulley and cog gets bigger because it's designed to clear even bigger cogs. Obviously a derailleur designed to allow a 34 w/ proper clearance will have 'too much' clearance if you're using a 25 or 28 large cog.

    Thirdly...this is why products like the Wolf Tooth Road Link are not a great idea. They're an especially bad idea if you're using a double crank. Yes they add clearance for larger cogs but they don't magically make a derailleur pulley cage any longer. If you're at the capacity of the derailleur and want to get a bigger cassette you're obviously going to need 2 things: clearance and more chain wrap. Guess which the Road Link doesn't do? Usually shift quality is also compromised as the Link moves the upper pulley further away from the cassette in the smaller/middle cogs so it can have more clearance in the larger ones.
    #promechaniclife

  5. #5
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    Quote Originally Posted by cxwrench View Post
    No...and the post above mine isn't exactly correct. Firstly, the extra cage length has ZERO effect on shifting. The shift takes place the upper pulley, so no difference in any way.

    Secondly the extra length really doesn't have anything to do with larger cogs directly. The ONLY reason for the longer cage is to wrap the extra chain you'll need for larger cogs. That's it. Nothing else. If you take a short cage derailleur(say Max 28t cog) and swap the cage to a longer one you won't have any success clearing bigger cogs (say 34t) because the upper pulley is traveling at the same angle as it moves across the cogs. If you changed the mounting point of the cage you'd gain some clearance which is generally how Shimano does it now. In a way I'm contradicting myself but my point is that the longer (Medium cage, Shimano doesn't make a 'long' cage road derailleur) is only long to wrap chain. In the old days when Shimano made doubles and triples the max cog size you could use was 27t for both derailleurs, the SGS just wrapped the extra chain you'd need for the triple up front than the SS short cage. There is some truth to the notion that the GS won't shift as well as the SS, but only on small cassettes. As the GS positions the upper pulley further away from the axle centerline as you shift to larger cogs the space between the upper pulley and cog gets bigger because it's designed to clear even bigger cogs. Obviously a derailleur designed to allow a 34 w/ proper clearance will have 'too much' clearance if you're using a 25 or 28 large cog.

    Thirdly...this is why products like the Wolf Tooth Road Link are not a great idea. They're an especially bad idea if you're using a double crank. Yes they add clearance for larger cogs but they don't magically make a derailleur pulley cage any longer. If you're at the capacity of the derailleur and want to get a bigger cassette you're obviously going to need 2 things: clearance and more chain wrap. Guess which the Road Link doesn't do? Usually shift quality is also compromised as the Link moves the upper pulley further away from the cassette in the smaller/middle cogs so it can have more clearance in the larger ones.
    Or to summarize, the only way a longer cage derailleur can accommodate bigger cogs on the cassette is if:

    1) the derailleur is also changed so that the upper pulley is farther away from the cogs for the larger cogs or

    2) if the reason you couldn't use a wider range cassette was because you couldn't wrap enough chain when on the smaller/smallest cog, NOT because the cassette had a bigger biggest cog.

  6. #6
    'brifter' is f'ing stupid
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    Quote Originally Posted by Kerry Irons View Post
    Or to summarize, the only way a longer cage derailleur can accommodate bigger cogs on the cassette is if:

    1) the derailleur is also changed so that the upper pulley is farther away from the cogs for the larger cogs or

    2) if the reason you couldn't use a wider range cassette was because you couldn't wrap enough chain when on the smaller/smallest cog, NOT because the cassette had a bigger biggest cog.
    ^Exactly^
    #promechaniclife

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