Ideal Crank Length (Page 2)

Originally posted by mike761

Originally posted by marcag

Originally posted by Left Brain

Originally posted by DarkSpeedWorks

Originally posted by Left Brain

I enjoy reading these discussions....but I also know that you could take 10 riders of varying abilities, keep them training the same, and change their their crank lengths all you want.....they will finish in the same order.   So, there is that.

That may be true. Or not. It is kind of like saying that youu could take 10 riders of varying abilities, keep them training the same, and change their head wear all you want (some going bare, some using road helmets, some using aero road helmets, some using basic aero helmets, and some using advanced aero helmets).....they will finish in the same order. That could also be true. But, I bet in both cases, even if they finish in the same order, they likely won't finish with the same time spreads between each. Especially in the case of crank length, if you test on highly varying terrain (can't just do this test on the flats) and if you use some very short and very tall riders. The short riders will have a tough time with the long cranks and the tall riders will have a tough time with the short cranks. Or, at least, such has been my experience.

For the lengths that are most discussed with regard to this board and triathlon (160-175...BARELY OVER 1/2 INCH) I would be willing to bet on an absolutely negligible difference from one rider to the next as far as power, cadence, etc.  I can maybe see a bit of a difference due to opening the hip.....but no way on the other data.  It's mostly much ado about nothing.

yep. The hip difference can be significant for old farts, speaking from experience With the Vectors you can measure all kinds of wonderful things that I have measured with my 165s and 172.5s on my road bike. The one thing that I found for me, is that cadence is not the thing that is self selected, the force you apply to the pedals is, and you will adjust cadence to the crank length to achieve the right force. At least it did for me. Winter on a computrainer is a wonderful time to play with all kinds of stuff.

I went from 172.5 to 165, It may not seem like much but I noticed the difference. I did it on borrowed cranks at first($0 invested), because I just did want to spend the money if was not going to make a difference. Where I noticed it most was going up inclines somewhere between 2% and 5% where I was able to stay aero and breath easy going up in aero vs before the change always breathing hard and coming out of aero. This was on local rides that I did all the time. So it was immediately a noticeable difference. The other advantage was going with shorter cranks you raise the seat to compensate which puts you in a more aero position. (something LB can't even argue with

I don't argue with the hip angle......I'm not so sure about the "more aero" position.  Yes, your seat has to come up with shorter cranks.....but it has to be moved back too.....now your bars may have to be moved, and possibly the pads.....more aero?  I dunno...... maybe, maybe not.  I won't argue that if you are more comfortable you will stay in an aero position longer, so there's that.

Look, we've been dealing with Jr.s set-up for a few months so I've been having these discussions a lot. (he got a quarq on a sponsor deal so made some changes that had been recommended) Switched him from a compact crank to standard, shortened his crank arms 10mm to start with, then ended up at 2.5, blah,blah,blah.......and this is on a road bike.  He and I have listened to all manner of "experts" regarding gains and losses in power, cadence gain or losses (he rides  at ~110 normally with a FTP ~340), ability to run better off the bike (a surprising number of triathlon "experts" subscribe to that), ability to breath better on the bike, and on and on.  Last week, as we were talking about it again, the kid looks at me and goes, "I'm done, this is all a bunch of bullchit....I was fine on the compact and 175's and this is just pizzing me off changing stuff". (his knee started bothering him, then his back)  I think he's right.  I'm watching and talking to some of his peers who are being pushed that direction as well.....everyone's spending more money....nobody is making any magical gains....hmmmmmm.

For comfort on a tri bike I can concede a possible benefit.  For ANY other reason......no.

Yeah, that ain't all.

It can be frustrating to put all the time into something only to find out it may have already been pretty good. Probably not the only time it'll happen. I can be a real PITA for some otherwise good fitters too. I have felt the 2.5mm crank size difference (though did get used to it with time). I did feel the slight saddle adjustment the fitter made (had me go blind for it) and ended up going back. I've still tried to take in their thoughts on how they're going about making decisions and tweaking things on my own as it's just really frustrating for them dealing with a special situation at times. Or my stubbornness. 

Oh....I get it.... and I'm damn certain of my own stubbornness to fall back to "forget this crap and go to work" (I'm thrilled that I may have passed that on to my own kid).....my problem is that "go to work" has been a winning formula.... some of this other stuff, not so much because the time/money spent on it is just wasted.  I don't begrudge someone spending the money (it ain't mine), but for chrizzakes , take that money and put it into some good work overseen by someone who really knows how to get the most out of a bike workout and get THAT knowledge.....now you've bought something that REALLY helps your race.

I think it's good that many folks who do triathlon have money to burn...truly, I do.  It keeps the local shop floating and props up the "industry".  BUT....a pig in a silk dress is still a pig.  That's where I fall off the page.

Originally posted by Left Brain

Originally posted by mike761

Originally posted by marcag

Originally posted by Left Brain

Originally posted by DarkSpeedWorks

Originally posted by Left Brain

I enjoy reading these discussions....but I also know that you could take 10 riders of varying abilities, keep them training the same, and change their their crank lengths all you want.....they will finish in the same order.   So, there is that.

That may be true. Or not. It is kind of like saying that youu could take 10 riders of varying abilities, keep them training the same, and change their head wear all you want (some going bare, some using road helmets, some using aero road helmets, some using basic aero helmets, and some using advanced aero helmets).....they will finish in the same order. That could also be true. But, I bet in both cases, even if they finish in the same order, they likely won't finish with the same time spreads between each. Especially in the case of crank length, if you test on highly varying terrain (can't just do this test on the flats) and if you use some very short and very tall riders. The short riders will have a tough time with the long cranks and the tall riders will have a tough time with the short cranks. Or, at least, such has been my experience.

For the lengths that are most discussed with regard to this board and triathlon (160-175...BARELY OVER 1/2 INCH) I would be willing to bet on an absolutely negligible difference from one rider to the next as far as power, cadence, etc.  I can maybe see a bit of a difference due to opening the hip.....but no way on the other data.  It's mostly much ado about nothing.

yep. The hip difference can be significant for old farts, speaking from experience With the Vectors you can measure all kinds of wonderful things that I have measured with my 165s and 172.5s on my road bike. The one thing that I found for me, is that cadence is not the thing that is self selected, the force you apply to the pedals is, and you will adjust cadence to the crank length to achieve the right force. At least it did for me. Winter on a computrainer is a wonderful time to play with all kinds of stuff.

I went from 172.5 to 165, It may not seem like much but I noticed the difference. I did it on borrowed cranks at first($0 invested), because I just did want to spend the money if was not going to make a difference. Where I noticed it most was going up inclines somewhere between 2% and 5% where I was able to stay aero and breath easy going up in aero vs before the change always breathing hard and coming out of aero. This was on local rides that I did all the time. So it was immediately a noticeable difference. The other advantage was going with shorter cranks you raise the seat to compensate which puts you in a more aero position. (something LB can't even argue with

I don't argue with the hip angle......I'm not so sure about the "more aero" position.  Yes, your seat has to come up with shorter cranks.....but it has to be moved back too.....now your bars may have to be moved, and possibly the pads.....more aero?  I dunno...... maybe, maybe not.  I won't argue that if you are more comfortable you will stay in an aero position longer, so there's that.

Look, we've been dealing with Jr.s set-up for a few months so I've been having these discussions a lot. (he got a quarq on a sponsor deal so made some changes that had been recommended) Switched him from a compact crank to standard, shortened his crank arms 10mm to start with, then ended up at 2.5, blah,blah,blah.......and this is on a road bike.  He and I have listened to all manner of "experts" regarding gains and losses in power, cadence gain or losses (he rides  at ~110 normally with a FTP ~340), ability to run better off the bike (a surprising number of triathlon "experts" subscribe to that), ability to breath better on the bike, and on and on.  Last week, as we were talking about it again, the kid looks at me and goes, "I'm done, this is all a bunch of bullchit....I was fine on the compact and 175's and this is just pizzing me off changing stuff". (his knee started bothering him, then his back)  I think he's right.  I'm watching and talking to some of his peers who are being pushed that direction as well.....everyone's spending more money....nobody is making any magical gains....hmmmmmm.

For comfort on a tri bike I can concede a possible benefit.  For ANY other reason......no.

I've said forever that crank length is a biology issue, not a physics issue. If shorter were better then we'd all pedal with our ankles and be crazy aero. Dominant muscles and range of motion are a bigger consideration. Ran across this a while back that does a better job making the point.

http://alancouzens.com/blog/cranklength.html

" a crank length that is too short (a less common problem) will result in a loss in economy as the athlete is not taking the prime mover muscles through their full range of motion. Muscles are most efficient when they fully contract from their maximal resting length. Contracting from an already shortened position is less efficient. Period. "

I also find it interesting when you look at the crank length of some of the stronger cyclists in our sport. Why on would someone like Kienle ride 175's or Hoffman 172 or Frommhold 175 or Van Lierde 175. I'll be the first to say there are big names on shorties, but if it was so universal like using aerobars or discs, then everyone would be doing it.