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crank arms

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  • March 29, 2018 at 8:22 pm #28304
    Newave2002

    hello people,

      I was wondering if anyone has ever switched form a 172.5mm arm to a 170mm arm and if you noticed any difference? The groupo I want to buy has a 170mm arm and not the 172.5mm/ I think  I will get the groupset with the 170mm and I can always buy 172.5mm if needed, but want to ask you.

    Thanks,

     

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Viewing 12 replies - 16 through 27 (of 27 total)
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  • March 30, 2018 at 5:45 am #915787
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    Anonymous

    Boatsie wrote:

    Boatsie wrote:
    kevvjj wrote:

    Get a pen, ruler and paper. Draw a vertical line about 1 cm in height. Now draw another 1cm vertical line exactly 2.5mm to the right of the first. Look at the size of the gap between the two vertical lines and tell yourself you could tell the difference when riding.

    You can notice it. Set your seat post at height. Can’t reach pedal if risen 25mm but who cares if lowered 25mm. Really depends upon your range of motion and like Kev indicates; most the time it wouldn’t matter. Longer stroke gives more torque, eg turns wheel using strength Shorter stroke revs easier, eg rhythm development of horsepower. Trucks have long stroke. Race cars have fast stroke. Each develop the equal horsepower yet each horsepower is different . If too easy too pedal then torque it with longer arms or if too fast when spinning, shorten. I’m lost too bro.. I’d use 165-185 and learn with what I’m given. I’d like longer cranks but that’s because I don’t climb, I’m tall cogged and the freewheel freewheels.

    25mm is a factor of TEN greater than 2.5mm, you really need to recheck what’s written and how mm/cm are different.

    Raising your saddle 2.5mm would not make a difference as to whether you can reach the pedals or not, to suggest so is simply bogus.

    the difference in crank length between a 170 to a 172.5 is going to produce such an infintessimally small change in torque that you would not know, it’s in your head.

    “Too easy to pedal” is down to the gearing, it’s virtually nada to do with the crank arm length, you even state yourself that you “learn with what I’m given”, you change your gear ratio to whatever you find best for the conditions, the crank length is not relevant to this and is more historical incorrect thinking repeated time and again.

    March 30, 2018 at 4:56 am #915785
    0
    SteveAustin

    i use 175 on all my bikes. I

    i use 175 on all my bikes. I bought a bike with 172.5 and it just felt odd compared to the 175 cranks i was used to. It might only be a small difference but when folk are being being convinced to part with money for bikefits, i think its worth getting the size you want and like. Im sure someone will take your money and tell you you need shorter cranks…

    I switched to a  180 crankset (ss if that matters) and it just felt too big. so have stuck with 175 as that works for me.

    March 30, 2018 at 4:47 am #915783
    0
    Boatsie

    kevvjj wrote:

    kevvjj wrote:

    Get a pen, ruler and paper. Draw a vertical line about 1 cm in height. Now draw another 1cm vertical line exactly 2.5mm to the right of the first. Look at the size of the gap between the two vertical lines and tell yourself you could tell the difference when riding.

    You can notice it.
    Set your seat post at height. Can’t reach pedal if risen 25mm but who cares if lowered 25mm.
    Really depends upon your range of motion and like Kev indicates; most the time it wouldn’t matter.
    Longer stroke gives more torque, eg turns wheel using strength
    Shorter stroke revs easier, eg rhythm development of horsepower.
    Trucks have long stroke. Race cars have fast stroke. Each develop the equal horsepower yet each horsepower is different .
    If too easy too pedal then torque it with longer arms or if too fast when spinning, shorten.
    I’m lost too bro.. I’d use 165-185 and learn with what I’m given. I’d like longer cranks but that’s because I don’t climb, I’m tall cogged and the freewheel freewheels.

    March 30, 2018 at 3:45 am #915781
    0
    Anonymous

    Get a pen, ruler and paper.

    Get a pen, ruler and paper. Draw a vertical line about 1 cm in height. Now draw another 1cm vertical line exactly 2.5mm to the right of the first. Look at the size of the gap between the two vertical lines and tell yourself you could tell the difference when riding.

    March 29, 2018 at 11:25 pm #915779
    0
    Boatsie

    I don’t notice much between a
    I don’t notice much between a 172.5 and a 175 mm crank.
    The 175 is on a fixie though and I like that feeling that while resting the leg will is cycling although not sure if because of the larger circle or the consent spin.
    There is a difference but they’re both fun and doing their job.

    March 29, 2018 at 11:14 pm #915777
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    Newave2002

    but will 2.5mm really make a

    but will 2.5mm really make a difference?

     

    March 29, 2018 at 10:28 pm #915775
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    Stef Marazzi

    I noticed 170mm is a lot more
    I noticed 170mm is a lot more spinny than the larger sizes.

    March 29, 2018 at 10:22 pm #915773
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    Jack Osbourne snr

    I have chainsets in 170, 172

    I have chainsets in 170, 172.5 and 175.

    Technically, a shorter crank should be better for spinning lower gears and longer ones better at lower cadence with higher gears.

    In reality, I dont notice the difference. 

    March 29, 2018 at 9:50 pm #915771
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    Newave2002

    so, going from 172.5 to 170

    so, going from 172.5 to 170 wouldn’t really make a difference. I guessing if I switched from 172.5 to 170 that I would soon forget about it. So with a shorter arm, my trunover would be quicker perhaps, than that of the 172.5 and good for climbing long hills.

    March 29, 2018 at 9:26 pm #915769
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    Anonymous

    I went from 175 to 165 and

    I went from 175 to 165 and you soon forget about it. 

    March 29, 2018 at 9:24 pm #915767
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    Newave2002

     I don’t think there would be

     I don’t think there would be much difference between the 172.5mm and the 170mm. I can definitely see there being a difference between 175 and 170. I think it wouldn’t feel right like you said. I’m wondering if I would have to adjust my seat height up a little to accomodate the 170mm

    March 29, 2018 at 8:40 pm #915765
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    Canyon48

    I used to have 175mm cranks
    I used to have 175mm cranks and bought a bike with 170s, it just didn’t feel right. Can’t put my finger on it but it didn’t feel right.

    I switched to 172.5 cranks and stuck with them. They feel right.

    I think it’s just in my head though.

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