bloke

https://www.nettally.com/palmk/crankset.html

What do you think?
Make sure you read all of it.

urbanknight

Makes sense, and it came up with 170 for me. I ride 172.5 but I also have long thighs. From what I've read here on the forums (and we know that everything here is 100% accurate) you'd be better off deriving a formula that is based on the femur length. The competitive cyclist calculator has directions on that. They also recommend a book between the legs for the inseam measurement, which is probably better because more people have a book laying around than a clipboard.

Keep up the good work.

MrCjolsen

Where do I find 190mm cranks?

urbanknight

lol oops! I guess the equasion needs some adjustments. I did the math backwards and MrCjolsen has a 34-35" inseam, and I doubt that should require 190mm cranks.

It would be nice to do a study on people's thigh lengths and the length of cranks they ride. Use their guide on how to measure.
https://www.competitivecyclist.com/za...LCULATOR_INTRO

I'll start. Mine is 22.5" or 57mm and I ride 172.5 cranks.

urodacus

all my bikes have different length cranks.

Tequila Joe

33" inseam = 180mm cranks. A bit long IMO

littledjahn

Didn't Big Mig use 190s during TTs?

urbanknight

I believe so (at least in time trials), but I also believe that was with a cadence of 70-80

531Aussie

I'm not shooting the messenger, but I reckon it's crap, a bit dangerous, and the worst 'long crank' site by a mile.

When I was obsessed with crank length 2 or 3 years ago, I read his whole site about 5 times! In fact, I've got a printed out copy here with highlighter ink all over it. I read all of his stuff, all of Lennard Zinn's stuff, all of Andrew Bradley's stuff ( https://www.cranklength.info/ ), then I went out and bought 3 pairs of 180mm cranks for my 3 best bikes (I'm 6ft; 89.5cm inseam; size 43 shoe), grinded on them for a year, and have since gone back to 172.5s (mostly) and 175s. I rode no faster or more 'efficiently' with longer cranks -- all they did for me in the end was wreck my postion and hurt my knees a bit. The day I went back to 175s I felt like Superman, and smashed all my friends

Fair enough that cranks should be proportional, but this guy has basically pulled this "21.6% of inseam" figure out of his arse to suit his preferences. His whole premise for this "formula" is that a bunch of dudes with 31" inseams used 170mm cranks, and he just happens to think that this was "correct". In the 'old days' when everyone used 170, 172.5 and 175mm cranks, there were a whole stack of dudes with 32", 33" 34" and 35" (etc) using all those lengths. Why wasn't it "correct" that all the guys with 33" inseams were using 170s (20.3% of inseam)? Or why didn't he conclude that the guys with the 34" inseams using 172.2mm cranks was "correct" (20% of inseam)? He doesn't explain the difference, he's just found a figure to suit his theory.

He spends most of the site justifying proportional cranks -- which is obviously fair enough -- but he doesn't justify his ridiculous 21.6% measurement. If he insisted on a more reasonable proportion, like, say, 20% or even 20.5%, then ok, but 21.6% is insane!! I had a hard time pushing 180s, yet his formula would have me using 193mm cranks!! I laugh a little louder every time I write that. The bottom line is, there is no 6ft pro in whole world using 193mm cranks! Ulrich used 177.5s, so does Backstedt (he's 6ft3"), and Indurain used 180s (190s for some time-trials), but he's 6ft2" and probably one of the strongest time-trialers EVER! These lengths wouldn't be anywhere near 21.6% of inseam, unless they have unusually short legs for their height. The only pros using relatively very long cranks are the very short guys, and almost all of them are crap time-trialers.

Basically, longer cranks are harder to use: it's more difficult to "get on top of" them and pound the pedals, because your knees come up into into your chest, and the reach is too long. The only time I liked my 180s was pounding off the saddle over short hills.

There are no doubt a lot of short guys using relatively very long cranks, but should they be? I've got a theory that this could be one reason why shorter guys tend to be 'weak' on flat roads.

Kirby Palm also says that it's an old wive's tale that long cranks put more stress on knees. I reckon that's BS, and I'm sure a lot of people would agree with me. His 'buddy' Lennard Zinn even acknowledges that longer cranks can injure knees, and has included it as a warnig on his site.

All three of the main advocates of long cranks are all tall guys who were frustrated in the 70s and 80s at the lack of availability of cranks longer than 175mm, and I reckon they've generalised from their experiences and 'relief' at eventually finding longer cranks.

MrCjolsen

34.75 to be exact.

bloke

531Aussie, thank you. Perhaps, I need to do a bit more research before I go and change my cranks.