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  1. #1
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    Help me understand compact gearing

    I apologize in advance for my ignorance on this topic.

    Over the winter I bought a carbon crankset for my Poprad. Looked cool, was carbon, weighed less than my existing crankset, and had similar (so I thought) chainrings -- the original Poprad (Bontrager) rings were 46/38, the FSA rings are 46/36. The FSA crankset I bought and installed is a compact crankset. I had no idea what that meant when I bought it. After one ride on the flats, I realized I was missing gearing on the high end.

    My question is, how off am I now, and what might I do to get back to where I was? I have two wheelsets, a cross set with 12-25, and a road set with 12-26. I thought the gearing was perfect then. I climbed well with those setups, rarely dropping to the 38 when climbing, and I live in CO (which makes me wonder if I'll ever use a compact 36) so I'm worried that I screwed up by unknowingly going to a compact crankset.

    So do I need new rear cog clusters? Or get bigger rings for the compact crankset?

    Thanks,
    Last edited by KeatonR; 06-01-07 at 12:04 AM.
    Lemond Poprad / Jamis Dragon Race 29er / Surly LHT
    "the feel of steel"

  2. #2
    Just a commuter stockholm's Avatar
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    this explained it all to me, at least: http://bikeforums.net/showthread.php?t=241679

    HTH

  3. #3
    cs1
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    Quote Originally Posted by KeatonR
    I apologize in advance for my ignorance on this topic.

    Over the winter I bought a carbon crankset for my Poprad. Looked cool, was carbon, weighed less than my existing crankset, and had similar (so I thought) chainrings -- the original Poprad (Bontrager) rings were 46/38, the FSA rings are 46/36. The FSA crankset I bought and installed is a compact crankset. I had no idea what that meant when I bought it. After one ride on the flats, I realized I was missing gearing on the high end.

    My question is, how off am I now, and what might I do to get back to where I was? I have two wheelsets, a cross set with 12-25, and a road set with 12-26. I thought the gearing was perfect then. I climbed well with those setups, rarely dropping to the 38 when climbing, and I live in CO (which makes me wonder if I'll ever use a compact 36) so I'm worried that I screwed up by unknowingly going to a compact crankset.

    So do I need new rear cog clusters? Or get bigger rings for the compact crankset?

    Thanks,
    A lot of riders that switch to compact swap cassettes to an 11 tooth version. See if you can beg/borrow one and try it out. It will return some of the top end you are missing. Good luck

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

  4. #4
    Double Secret Member CaptMatt15's Avatar
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    I don't understand how you are loosing speed in the flats when you're highest gear (46-12) is the same as with your old cranks. The only difference is going to be if you are in your smaller chain ring (a 36, as opposed to a 38).

    Technically, both of your cranks would be considered "Cyclocross Compacts" because the rings are different than a traditional Road compact (a 50/34).
    2007 Redline Conquest
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  5. #5
    Senior Member
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    I dunno, felt like I had a lot more pedaling that I could have done when I went out.

    From what I've now been reading from the link above, it appears I've been overthinking this a bit. One thing I will do is order a new 38 inner ring from FSA and ditch the 36, and then I'll think about going to a cogset with an 11 for the road wheelset, and leave the cross wheelset the same.
    Lemond Poprad / Jamis Dragon Race 29er / Surly LHT
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  6. #6
    Senior Member
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    Have done some more digging and this is looking really useful:

    http://sheldonbrown.com/gears/

    Especially for someone who is (obviously) not a math guy.
    Lemond Poprad / Jamis Dragon Race 29er / Surly LHT
    "the feel of steel"

  7. #7
    So I says to Mable I says somnambulant's Avatar
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    yeah, 46 = 46. Doesn't matter if it's a compact or standard crankset. Did you perhaps change the crank arm length as well?
    -Milpool

  8. #8
    cs1
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    Quote Originally Posted by KeatonR
    I dunno, felt like I had a lot more pedaling that I could have done when I went out.

    From what I've now been reading from the link above, it appears I've been overthinking this a bit. One thing I will do is order a new 38 inner ring from FSA and ditch the 36, and then I'll think about going to a cogset with an 11 for the road wheelset, and leave the cross wheelset the same.
    If your problem is top end gearing, don't waste any money on a new inner chainring. It has ZERO effect. Get the new cassette. Good luck

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

  9. #9
    Senior Member
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    Definitely now understanding that a 46 = 46. Was in a bit of a late-night panic when I first posted, thinking I had screwed up by going to a compact crankset without even knowing what it was.

    I think I will try an 11 on my road wheelset and from there think about a 38 inner ring. I never use the third ring on my mountain bike, and I liked the 38 on my previous setup for climbing.
    Lemond Poprad / Jamis Dragon Race 29er / Surly LHT
    "the feel of steel"

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