In article <8b4b7de4.0302251831.442928b
[email protected]>,
[email protected] (Bluto) wrote:
> Ryan Cousineau <
[email protected]> wrote:
>
> > Would going to smaller cranks help? I'm 5'6", ride 51-53 cm frames, and use 170 mm cranks. I've
> > got an opportunity to pick up some 167.5 cranks at a good price. Will the 5 mm crank circle
> > diameter change even be noticeable? I'm thinking yes, since it's close to the size of the saddle
> > height chances I have made, but was looking for some experienced opinions.
>
> I doubt you'll notice the difference in crank circle diameter unless the 170mm arms you've been
> using are detrimentally long for you (causing you to move some parts of your body other than your
> legs in order to perform your pedal stroke).
Thanks, first of all, to everyone for the opinions on this thread. It's been...interesting.
> There is some threshold at which a crank becomes too long, for instance when one's knees hit one's
> chest while riding in the drops, or when the knee at the top of the pedal stroke begins to bind
> and resist further bending. Whatever this threshold, it is certain and identifiable for any given
> rider and bike.
>
> I postulate that the "best" crank length for any rider/bike combination is the longest one that
> gives no ill effects. However, it's clearly preferable to err on the short side of that length
> than to exceed it by even a little bit.
> IMO it's unlikely that even at 5'6" your legs are too short to pedal properly with 170mm cranks.
> You are, of course, the one who gets to make that judgement. But my advice to you is, if you think
> that 170mm cranks are actually too long for you, then why shorten them by only
> 2.5mm? Why not 165mm or even 155mm cranks? There's no point in almost addressing a suspected
> problem when you could be certain about
> it.
I actually don't have major mechanical problems with 170 mm cranks. At most, I'm sure they're not
the major thing keeping me from being faster on the bike at the moment.
What has been bothering me is issues other than power. As I mentioned, I have an achilles tendon
issue. Of course, the standard solution is to drop one's seat slightly, and work on cleat
positioning. That's fine.
But I also have had serious knee issues in the past, long predating cycling, and as you know, the
proper solution for that is to raise the seat.
I think the needs of these two conditions are not necessarily overlapping. It doesn't bother me on
short rides, so for now, I will do nothing. But the third way that occurred to me was shrinking the
crank circle. With a smaller crank, I will get less knee AND ankle flex on each stroke, which should
help free me from my knee and ankle problems. I'm going to keep tracking it for now, but we'll see.
> Legs vary in length by much more than the 8-9% difference between "very short" (165mm) and "very
> long" (180mm) crankarms. If your leg length is outside of the middle 10% of the overall range, it
> stands to reason that you might be better served by a crank that is shorter or longer than Shimano
> and Campagnolo supply.
My legs are not unusually short for my height. I can't remember all the leg measurements I've done,
but I wear a 30" pant leg.
Thanks,
--
Ryan Cousineau,
[email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club