Discussion: Wow.

Wow.

thanks!

How do you like the big cranks?

They're pretty much the greatest thing ever. The mtb feels like a kids bike now.

It's so cool that you like it.

I was trying to figure out why crank length isn't talked about much. It seems like there ought to be more sizes of cranks out there.

I got some 1988 U.S. Army Anthropometry survey data (they have it for men and women).

For men, Crotch Height is:

Average 837.19mm, 32.96in
s 46.25mm

-3s: 698.45mm, 27.50in
+3s: 975.94mm, 38.42in

Assuming 170mm cranks are "average" and scaling linearly:

-3s: 141.8mm
+3s: 198.2mm

For women the data is:
Average: 771.35mm, 30.37in
s: 44.14mm

-3s: 638.92mm, 25.15in
+3s: 903.78mm, 35.58in

I'm guessing there is an advantage for long legs to have a slower cadence, so I'm thinking the linear assumption is faulty. Or maybe the idea is to have a specific amount of hip motion (the swept angle of the thigh?). It seems like that would be linear, though.

Somewhere I've got a copy of Bicycling Science. I think they talk about this in there.

We missed you and cjross this weekend, though your epic ride looks to be a satisfactory proxy.

Yeah we were planning on going, but any useful tickets were stupidly expensive this weekend for some reason. Plus I've been riding too much instead of running, so I would have bailed on the long anyway.

heh, running.

Big crank blog post:

http://bikeblather.blogspot.com/2014/07/crank-leng...