Is there an ideal crankarm length with a SS?- Mtbr.com
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  1. #1
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    Is there an ideal crankarm length with a SS?

    I'm considering putting together a rigid single-speed 29er and found that I have a general question regarding SS crankset that I hope someone can help me out with.

    What size crankarm is typical for SS, assuming a 32 tooth chainring? I was about to default with my familiar 175mm but started wondering if that was typical for SS.

  2. #2
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    I run a Truvativ Stylo with 180mm arms on my Dambala. Does the extra 5mm make a noticeable difference in leverage? I don't know but the bike really climbs with them.

  3. #3
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    Hey Moozh, I am not hijacking your thread but I have wondered the same thing and IF I could add a second question to your thread it would be, to be answered by the ladies, What is your ideal crank size?? Hope that's cool with you?

  4. #4
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    Quote Originally Posted by blasted
    Hey Moozh, I am not hijacking your thread but I have wondered the same thing and IF I could add a second question to your thread it would be, to be answered by the ladies, What is your ideal crank size?? Hope that's cool with you?
    If you have to ask, it's too small.

  5. #5
    Ovaries on the Outside
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    This is just going to be a personal preference, based on whether you are a spinner or a masher, how tall you are, how long your shins are, if you wear socks or VFF, run marathons or like pink thongs (on you or someone else).

    Sorry, but I answered for the ladies. That being said, I am pretty sensitive, so my opinion should count for something.

  6. #6
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    Same as your road bike, cross bike, mountain bike. The optimal crank length for your body measurement does not change across platforms.

    Relevant here, does a longer than normal crank give more leverage?

    It's been tested empirically and the benefit (very, very small if any) is made moot or worsened by the loss of efficiency in spinning the less efficient crank length.

    A crank longer than optimal for your body creates bigger dead spots in each revolution. If you don't believe this then you don't believe there is such a thing as a most efficient crank length for each person's physique. Perhaps you don't, your choice.

    But if you do believe there is, then you agree that using a longer crank lengths on an mtb for increased gain is a very popular and unchallenged myth..

  7. #7
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    Get your dam mind out of the gutter!!!

  8. #8
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    Quote Originally Posted by the pope
    Same as your road bike, cross bike, mountain bike. The optimal crank length for your body measurement does not change across platforms.
    Disagree! I like my 175mm for singletrack, but I hate spinning on them. SS with my road bike is 170 because otherwise it is too hard to keep a good speed up with good pedaling technique.

  9. #9
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    There is indeed an ideal crank length for SS, and it varies with each individual rider. Just like there's an ideal frame size for each rider.

    --Sparty
    disciplesofdirt.org

    We don't quit riding because we get old.
    We get old because we quit riding.

  10. #10
    All 26.5" all the time!
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    With a single speed mountain bike, the traditional rules of crank sizing get thrown out the window beacuse:

    1. We don't have multiple gears.
    2. We don't stay seated.
    3. It's impossible to maintain a steady cadence.

    The pedaling dead spot is the least of our worries. If efficiency mattered, we'd be on geared bikes.

  11. #11
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    The 165 mm setup i have on my 26er works pretty well, then again i am a shorter rider on a frame size that wasnt designed for me
    "If women don't find handsome , they should at least find you handy."-Red Green

  12. #12
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    Quote Originally Posted by Zanetti
    With a single speed mountain bike, the traditional rules of crank sizing get thrown out the window beacuse:

    1. We don't have multiple gears.
    2. We don't stay seated.
    3. It's impossible to maintain a steady cadence.

    The pedaling dead spot is the least of our worries. If efficiency mattered, we'd be on geared bikes.
    Your last sentence is a mystery to me.

    An inefficient crank length doesn't become efficient when removing gears or standing - just as an efficient crank size doesn't become less. And the (seldom) trails or significant areas of trails where geared bikes riders can maintain a steady cadence provide the same opportunities for those on single speeds.

  13. #13
    master blaster
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    Quote Originally Posted by SeaBass_
    I run a Truvativ Stylo with 180mm arms
    i have the same set up on two bikes. one 29er and one 26er. also rode the same on a 650b but sold that bike.

  14. #14
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    Good replies... I was thinking if there was perhaps a tendancy to favor 180mm crankarms just for the additional leverage and torque it may afford but wasnt sure if it much of a consideration or noticable benefit. It would seem as with many things bicycle related the debate is not a settled one.

    and at "Blasted"..lol..n/p. But I've heard plenty say that size doesnt matter so long as you know how to use it all the while having a collective distain for the owners of notably short "cranks". All I can recommend if you employ of short "crank" is to turn out the lights, play in the dark and get yours before you get found out. YMMV... lol.

  15. #15
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    Quote Originally Posted by Sparticus
    There is indeed an ideal crank length for SS, and it varies with each individual rider. Just like there's an ideal frame size for each rider.

    --Sparty
    *ding*

  16. #16
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    Here's what I do...

    I'm left-footed (like most right-handers), so I have a 185 mm crankarm on the left, and 175mm on the right, but my SS is a fixie so I wobble all over.

    Is this wrong?

  17. #17
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    from a guy with wisdom, Wisconsin style, 175mm.

  18. #18
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    Quote Originally Posted by Jim Beam
    Is this wrong?
    Yes.
    - recognize

  19. #19
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    Quote Originally Posted by Jim Beam
    I'm left-footed (like most right-handers), so I have a 185 mm crankarm on the left, and 175mm on the right, but my SS is a fixie so I wobble all over.

    Is this wrong?
    make sure your crank arms are offset by 180 degrees, you should be fine.

  20. #20
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    Always rode a 172.5 on the road bikes and for the most part on my mtb. But my current set up has me on a 170. I can say that I spin like a bandit when on the smooth flats and guys on the 29'rs are rolling away from me. Granted this has alot more to do with gearing than anything. I can't say that 2.5mm has made any difference what so ever. I have ridden my bike and my wifes back to back with the seat set at the same height and can't tell any difference between the two.

  21. #21
    Retro Grouch
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    Yes, one my two track bikes I have a 165 on other a 166.5. I have three SS mtn bikes, two have 180s and one has 175. These are all ideal and typical crank sizes for single speed bikes
    Just one more rep and I get the toaster!

  22. #22
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    no.

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