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  • How far will a bike travel in 11/34 with one pedal stroke?
  • rob-jackson
    Free Member

    am i right in thinking:
    26″ wheel has a circumference of 207cm
    the 11/34 will give 3.09 rotations per pedal stroke/crank rotation

    there fore 6.4m?

    PaulD
    Free Member

    You look correct so far.

    This means that at 90rpm cranking you are doing 21.5mph

    More than enough for flat tarmac.

    PaulD

    rob-jackson
    Free Member

    cool 🙂

    umop3pisdn
    Free Member

    34/11 on 26” wheels is 80.3GI, probably a little high for general riding?

    somafunk
    Full Member

    Pretty much spot on ^

    34 x 11 on 172.5mm crank arms with a 26 x 2.25 tyre gives a gear inch of 83.4 = 6.65m for every revolution of the cranks

    Not worked out in my head nor am i a gear inch bore – I used the Bike Gears app for the iPhone, pretty nifty little app that is one of the few apps i continue to use – especially in the bike shop.

    avdave2
    Full Member

    I can’t see what crank length has to do with it.

    somafunk
    Full Member

    Neither can i avdave2? so here….have this award

    If i mentioned Gain Ratio then i guess it would have been relevant but seeing as i didn’t?….hey ho.

    The original poster did not mention what crank length he was using so as most folk either use 170mm or 175mm i thought i’d be a smart arse and use 172.5 to give a median gain ratio result but as i didn’t bother including the result in the above post i guess this entire explanation has been pretty irrelevant so far – fwiw the gain ratio is 6.15 so for every inch the pedal rotates around the bottom bracket the bike will travel 6.15″ forward.

    goatster
    Free Member

    A long way if its pointing downhill,

    avdave2
    Full Member

    Thank you Somafunk I have saved it with my collection of gold stars I have for eating all my tea. 🙂

    fourbanger
    Free Member
    geetee1972
    Free Member

    Well thought through; this is why I argue that very few people need a bigger gear than 34/11 or even 32/11 for anything other than road riding.

    Carax
    Free Member

    What would be the answer if on a 29″ wheel ?

    rob-jackson
    Free Member

    24.11mph

    somafunk
    Full Member

    No bother avdave2 🙂 , i gave myself a special “there – there” pat on the head for my cock-up regarding gain ratio.

    As for the 29″? :

    34 x 11 on 172.5mm Crank arms running a 29 x 2.25 tyre gives a gear inch of 89.1″ = 7.11m for every revolution of the cranks with a gain ratio of 6.58

    shermer75
    Free Member

    The only difference crank length will make is how far your shoes travel. Hrumph! 😉

Viewing 15 posts - 1 through 15 (of 15 total)

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