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  1. #1
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    Will I feel much difference between a 170 and 175 mm Crankset

    Recent events have me shopping for a new crankset. I have always ridden 175's but with the addition of new 5.5 rockers I have been having more pedal strikes than usual. I love the rockers except for this trait. Thought I might go 170mm on the new cranks to help alleviate this but have never ridden this size. What can I expect.

    Thanks.

  2. #2
    JMH
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    I have bikes with cranks as short as 165mm all the way up to 180mm. It doesn't bother me switching between them, the differences are marginal. You can spin a shorter crank more easily and you reduce pedal strikes, while longer crankarms are a bit more efficient for climbing.

    You may not even feel a difference.

    JMH

  3. #3
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    Thanks JMH. I'm also a novice at this outboard bearing deal. Are they really that much stiffer that the traditional BB setup. Thinking of the new XT FC-M770's. They will be replacing the old XT 751's with spined BB (ES71).

  4. #4
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    I really dont think you will notice a huge diff in rigidity, but you will find that they are more durable (properly setup of course).

  5. #5
    M070R-M0U7H FR3NCHI3
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    you WILL "feel" the difference. I run 170's on all my bikes because they have low BB's and I like the added clearance that they offer. I had to do some crank switching on some bikes recently and mounted some 175's on my HT and noticed it right away. I also feel I can corner a bit better with 170's - especially when the cranks are leveled to the ground...might have something to do with having my feet closer to the BB - who knows! All I know is that I like em'

    But like JMH mentioned - after a few miles you don't notice it the length difference anymore.

  6. #6
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    In my case, I feel 175 a little lethargic, while the 170 feels agressive.
    I used 175 before, and switched to 170.
    A week ago I tried a friend's bike with 175 crank arm length, and I felt the thing I said above

  7. #7
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    yes

    You will feel a difference, but for how long is anyones guess. My wife rides 170's and I 175, so when I work on her bike I give it a test and very much notice the difference. But, if I ride it for a mile or so the difference goes away, untill I get back on my bike and the 175 and then it is like, wow, for a mile or so then I am comfy again. What is better is up to you. How about a 172.5mm cranks?

    DT

  8. #8
    Amphibious Technologies
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    Quote Originally Posted by turnerbikes
    You will feel a difference, but for how long is anyones guess. My wife rides 170's and I 175, so when I work on her bike I give it a test and very much notice the difference. But, if I ride it for a mile or so the difference goes away, untill I get back on my bike and the 175 and then it is like, wow, for a mile or so then I am comfy again. What is better is up to you. How about a 172.5mm cranks?

    DT
    Ok, so there is a noticeable difference for about a mile, anyway. But what is the difference you speak of? Is the 175 easier to pedal uphill since it has more leverage?
    "The best you've ridden is the best you know" - Paul Thede, Race Tech

  9. #9
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    I prefer 170's. It gives a tad more clearance and, since I'm often out of shape, I find them easier to turn.

  10. #10
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    Thanks for weighing in everyone. I think I will go the 170 route. The new rockers give me an extra .4" on the downstroke. 5mm=.19". I also have been running my fork at 140mm instead of the 125mm I was before I got the rockers. Just feels better now at 140. This probably gives me an extra .1" at the BB. So all in all going with th 170mm cranks should restore things back to normal; except the ride is a lot smoother. Great job on those 5.5 rockers DT. Really breathed new life into the old Spot.

  11. #11
    trail fairy
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    Quote Originally Posted by SCUBAPRO
    Ok, so there is a noticeable difference for about a mile, anyway. But what is the difference you speak of? Is the 175 easier to pedal uphill since it has more leverage?
    Scuby I think DT talking about feel not advantages, as u said and JMH longer is better for leverage and climbing, but for the DJ/4X and the Spot would be the cut of point where a smaller crank might be better for some depending on u and the riding ya want to do.

    I feel the difference also, DH 165mm seems perfect for me, FR 170 (HL/RFX)
    RFX 175/170
    Spot ame could get away with it
    Flux nitrous well 175/180, I have a set of 180mm first gen XTR 2003 external bb model and they gave awesome leverage and power to my tree trunk legs.

    But little other bene's though I was smooth and wacked the pedals little, maybe I was better at picking lines way back then, though those followin me would never say that, the lefty was always straight and true from my view from the bars, but the rear end rarley stayed on the trail
    Just riding a muddy trail. . ..

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  12. #12
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    on the average, 170mm crank arms will be 5mm shorter than 175mm crank arms

  13. #13
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    Fo, will that be at the BB or pedal end?

  14. #14
    trail fairy
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    Quote Originally Posted by FoShizzle
    on the average, 170mm crank arms will be 5mm shorter than 175mm crank arms
    Fo your forgot to add in the rotatation of the crank 5mm at the bottom stroke 5 mm at the top that = 10mm

    So the answer is actully a full rotation will give you a 10mm leverage ratio differential

    Circumference = the square root divided by pie

    Just riding a muddy trail. . ..

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  15. #15
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    Quote Originally Posted by trailadvent
    Fo your forgot to add in the rotatation of the crank 5mm at the bottom stroke 5 mm at the top that = 10mm

    So the answer is actully a full rotation will give you a 10mm leverage ratio differential

    physics is ghey

  16. #16
    trail fairy
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    Quote Originally Posted by FoShizzle
    physics is ghey
    Qoute!! Forest Gump, greatest American Hero
    GHEY is as GHEY does



    Physics neva did get that far, I ride by feel, oh ctually everything I do is by feel, ya feel me
    Just riding a muddy trail. . ..

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  17. #17
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    only 5mm worth

  18. #18
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    Unicycle riders

    use all sort of different crank lengths. Shorter cranks will have a smoother spin, longer cranks will provide more leverage.
    Do you do lot of steep climbing, or tend to spin around the trails at speed?
    Craig, Durango CO
    "Lighten up PAL" ... King Cage

  19. #19
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    after years of riding 175's, I switched to 170's this year. I never noticed a difference other than less pedal strikes on rocks, but I must disclaim that: my wife says I'm an insensitive basturd, so....there you go.

  20. #20
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    Quote Originally Posted by Renegade
    my wife says I'm an insensitive basturd
    not only your wife, b!tch

  21. #21
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    Quote Originally Posted by FoShizzle
    not only your wife, b!tch
    okay, my bad:
    Evereyone says I'm an insensitive basturd. I agree. I'm good at it too.

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