Ryan Cousineau <
[email protected]> wrote:
> Mark Hickey <
[email protected]> wrote:
>> Remember that the 3% difference covers a range of human size that varies by more than 25%, and
>> not many complain about their cranks not fitting.
>
>It seems that mountain bikers are way less picky about crank lengths than road riders: roadies can
>generally find cranks from 165-175mm in 2.5mm increments (though the majority are 170 or 172.5).
>Almost all the mountain cranks I see are 175mm.
Isn't THAT the truth! I sometimes ride my wife's bike with it's 170mm crank (a Suntour XC Pro
gruppo), and really don't notice the difference. If anything it's easier to climb since it has a 20
tooth granny.
But I CAN feel the difference between a 170 on my tandem and the 172.5 on my road bikes. It's not a
big thing, and I don't worry about it... but when you're spinning real circles on smooth roads it's
more of an issue than when you're bouncing over rock gardens.
>Moreover, "leverage" seems to be a false god. You can get the same leverage with a smaller crank by
>lowering your gearing (thus requiring the same amount of torque at the pedal to move the bike
>forward).
Exactomundo.
>Furthermore, shorter cranks have two minor advantages and one huge advantage for most MTBers: the
>minor advantages are that they can be made slightly stronger and lighter, and the major advantage
>is better obstacle clearance.
They've done studies on biomechanical efficiency and found that there's basically a HUGE range where
the crank length doesn't really make a real difference. I think it's just what you're used to. If
the S-monster only built cranks in 150, 152.5 and 155, I'm sure we'd be having the same discussion
about the 150 vs 155.
>I ride 165mm on my road bikes (5'6", 156 lbs.) and I'm looking for shorter cranks for my good old
>94mm BCD rings, as it has 175mm on there now. This is completely rideable, but I hit things with my
>pedals too often and I think my pedalling would be more comfortable with smaller cranks.
The XT and XTR cranks do come in 165mm (as well as 180), but of course they're set up for 64/104mm
rings. I'm not aware of any 58/94mm crank that comes in 165mm length.
Mark Hickey Habanero Cycles
http://www.habcycles.com Home of the $695 ti frame