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Crank length and gearing

RichMTBRichMTB Posts: 599
edited March 2010 in MTB general
I'm replacing my old XT cranks with new ones and I've ordered 170mm crank arms

My main thought was to get a little bit more clearance when pedaling as I do get the occasional pedal strike on my Blur LT.

Will the shorter crank arms have any appreciable effect on the gearing. I have some memory of the term "gear inches" and know its related to crank length and gearing, but is 170mm vs 175mm big enough for me to notice any difference?
Step in to my hut! - Stumpy Jumpy Pacey


  • nicklousenicklouse Posts: 50,675 Lives Here
    sheldon has a big article on it.

    if you notice anything it will be that pedaling can be a bit harder as you are losing some mechanical advantage.

    Pedal strikes are more to do with technique than crank length.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • bomberesquebomberesque Posts: 1,701
    I'd be willing to bet that you won't be able to tell the difference tbh
    Everything in moderation ... except beer
    Beer in moderation ... is a waste of beer

    If riding an XC race bike is like touching the trail,
    then riding a rigid singlespeed is like licking it
    ... or being punched by it, depending on the day
  • Ho humHo hum Posts: 236
    You are only losing 5mm on your cranks, which is a fall of 2.9%.

    So, all other things being equal you will have to have the force on the pedals by 2.9% to generate the same amount of torque at the crank.

    Not really noticeable I think.
  • RichMTBRichMTB Posts: 599
    Sheldon (RIP) says not to worry either.
    Step in to my hut! - Stumpy Jumpy Pacey
  • bannedbikerbannedbiker Posts: 382
    nicklouse wrote:
    Pedal strikes are more to do with technique than crank length.

    +1 :wink:
    Giant Reign - now sold :-(
    Rockhopper Pro - XC and commuting
    DH8 - New toy :-)
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