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Thread: Compact crank and long-cage rear derailleur

  1. #1
    Saab2000's Avatar
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    Default Compact crank and long-cage rear derailleur

    Does one require the other?

    If I take my bike to Europe for a trip into the Alps this summer (which I would like to do) I may break down and get a compact crank. I doubt I can get over the big passes in the 39x23 anymore.... A 34x23 or even 34x25 might be needed.

    Does a compact crank basically require a long-cage rear derailleur?

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    dpcompt is offline VSalonistas
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    Default Re: Compact crank and long-cage rear derailleur

    Assuming you are talking about Campy, my 50-34 crankset and 12-25 cassette work perfectly with a shortcage rear derailleur. You may want to use a chain catcher in the front.
    don c.

  3. #3
    Miles is offline VSalonistas
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    Default Re: Compact crank and long-cage rear derailleur

    I believe a larger rear cog like a 28 may require one but don't see a reason the compact crank needs one.

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    lavi's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    your current rear der should work just fine. I have a compact on 2 bikes and have zero issues. A compact crank is all you need.

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    Default Re: Compact crank and long-cage rear derailleur

    I run a compact as well as a 12-27 or 12-28. It shifted fine for the mostpart.
    However, I opted to go for a medium cage derailleur; there was too much slack in small-small-ish combo on rough roads with the short derailleur for my liking.

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    bikinchris is offline VSalonistas
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    Default Re: Compact crank and long-cage rear derailleur

    Nope, but if the only change you make is a compact crank, you MAY have to shorten the chain a little.

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    Default Re: Compact crank and long-cage rear derailleur

    I run a 50/34 compact with an 11-25 cassette - I have this setup on two bikes. One bike has a short cage rear derailleur, and one has a medium cage. They both work just fine.

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    rustychisel is offline VSalonistas
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    Default Re: Compact crank and long-cage rear derailleur

    nope, as said.

    go compact, drop front derailleur about 3~4mm, tune carefully.
    A short cage derailleur on rear will take a 12-25 or 12-26 no worries, but best to avoid the big=big and small=small combinations, as you do. In any case depending on the bike and chainstay length you might find the 34 x smallest 2 cogs give unacceptable chain rub on the outer plate of the front derailleur. No biggie.
    Maybe take 2 links out of the chain, but it usually matters not one whit.

    Have fun

  9. #9
    sjb
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    Default Re: Compact crank and long-cage rear derailleur

    Heck, I run a Campy compact, 50x34 with a Chorus short cage RD and a 13-29 (you ever try the La Sal Mountain Loop in Moab?) without any problems.
    Yup, I avoid big-big, but that's all I do.

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    Someguy_Onabike is offline VSalonistas
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    Default Re: Compact crank and long-cage rear derailleur

    Chiming in here, I run compact cranks (34-50) on both 9 and 10 speed bikes and switch between 11-27, 12-25, and 12-27 with standard Dura-Ace and Force rear derailleurs. Running Shimano cranks/rings and I have no problems. However I tried running a compact (34/50) from another company and seemed to have issues with dropping the chain. Moral of the story, buy a crank with good rings. That experience was the genesis of the advertising campaign: "*** cranksets, now with automatic chain dropping technology". Dropping the chain sucks so I left the chain catchers on when I changed cranks.

    When I first got the compact years ago I got the FSA front. d. that was supposed to work better with the smaller rings. That was a waste of $.

  11. #11
    twowheels's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    jim you could retain the 39-53 and run a campy 13-29 with a short cage rear. but i have no experience with the combo in your question but note that campy also makes a medium cage rr drlr.

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    lavi's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    Quote Originally Posted by twowheels View Post
    jim you could retain the 39-53 and run a campy 13-29 with a short cage rear. but i have no experience with the combo in your question but note that campy also makes a medium cage rr drlr.
    I've run this above combo too. However, I think a 27 out back with compact will still give a lower climbing gear. This would most likely be the most inexpensive fix with just grabbing a new cassette.

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    Dave Thompson is offline VSalonistas
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    Default Re: Compact crank and long-cage rear derailleur

    Quote Originally Posted by Saab2000 View Post
    Does one require the other?

    If I take my bike to Europe for a trip into the Alps this summer (which I would like to do) I may break down and get a compact crank. I doubt I can get over the big passes in the 39x23 anymore.... A 34x23 or even 34x25 might be needed.

    Does a compact crank basically require a long-cage rear derailleur?
    Typically the change to a compact crankset doesn't require a change to the rear derailleur.

  14. #14
    Rico's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    With Record 10 Campagnolo rcommend a mig-cage only for 50x34 and 13-29. I use this setup on Brevets in the hills.
    There are some pretty big jumps in gearing but the 29 is nice for the long long cimbs.
    People have run a short cage in that setup if:
    1. Deraileur hanger is long enough and/or you can adjust the B-scew to move the upper jockey wheel enough to clear the 29.
    2.Pay careful attention to the chain length. OR you can just avoid the big/big.

    I think later Record-11 modified the RD to allow this gearing w/o a mid cage.

    The long cage was intended for the triple.

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    Shinomaster's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    My cross bike has short cage Centaur Rd with a 36/46 up front ( 13-26 in back). Works great.

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    SteveP is offline vSalon Legend
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    Default Re: Compact crank and long-cage rear derailleur

    my europe bike has gone compact w/27. short cage no problem.
    those climbs take a loooong time.

  17. #17
    Saab2000's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    Quote Originally Posted by SteveP View Post
    my europe bike has gone compact w/27. short cage no problem.
    those climbs take a loooong time.
    Yes, they do. I'd like to ride over the Klausenpass again. I've done it a couple times before and I think it was probably the better part of 90-120 minutes to get to the top.

  18. #18
    SteveP is offline vSalon Legend
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    Default Re: Compact crank and long-cage rear derailleur

    saab,
    you must be stuck somewhere at some airport, no?
    funny, it never snows east of the mississippi, hardly.

    my longest climbto date is the stelvio. 1:55. one flat spot in the middle of a k or so.

  19. #19
    Saab2000's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    Quote Originally Posted by SteveP View Post
    saab,
    you must be stuck somewhere at some airport, no?
    funny, it never snows east of the mississippi, hardly.

    my longest climbto date is the stelvio. 1:55. one flat spot in the middle of a k or so.
    Actually, I'm stuck at my crashpad in Norfolk..... No mountains here, except the bridge over the waterway down in Pungo. Sometimes you have to shift to get over it. But a single-speed road bike would be just fine down here too.

    The Klausenpass is long, something like 29km from bottom to the top, but this total length includes a flat section and even a km or so of descent, which is heartbreaking because you fight for the elevation and then descend and then have to re-climb that stuff. But it's a spectacular climb with lots of places to fall thousands of feet (motorcyclists do this every year once or twice) and at the top there's a tiny chapel and a place to buy something and fill up the water bottles. But you can't hang around because it's cold. My times up there I am guessing it was only in the 40s at the top. And getting chilled before a 15 mile descent is no fun....

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    steve garro's Avatar
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    Default Re: Compact crank and long-cage rear derailleur

    you only need a long cage {usually} if you go over 30T on the rear cassette. if you turn in the B-tension screw and the chain/pulley still run roughly with chunky resistance against the big cog then you need to bump up to a med. or a long cage. - Garro.
    Steve Garro, Coconino Cycles.
    Frames & Bicycles built to measure and Custom wheels
    Hecho en Flagstaff, Arizona desde 2003
    www.coconinocycles.com
    www.coconinocycles.blogspot.com

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