Just try to pry a big, heavy rock off the ground with a 6-inch plank. Cavemen figured out how to produce more force by using a longer lever. What part of this is hard to understand? Try riding with 100mm cranks some time. Or 50mm cranks. There is probably an optimal crank length for each rider and my guess is the Rohan Dennis knows which crank length suits him best. Cheers from NZ, Scott

Shame a garbage poster has hijacked an interesting thread. But it does show why so many dumb ideas never seem to fully die.

I'm presenting at ISCO in Munster Germany next month on Crank Length and Aerodynamics.

I'll be combining data from my lab on crank length with wind tunnel data shared by a few heavy hitters in aero testing. Here is the current draft of my abstract:

This presentation will focus first on crank length and then on aerodynamics. Research has consistently shown that crank length, across a wide range (145-195mm), does not influence maximal sprint power or efficiency during submaximal cycling. I will present data from several studies from my lab and discuss the underlying muscle physiology and biomechanics to help explain this somewhat controversial notion. Because crank length does not influence maximal or submaximal power, it can become an integrated element of overall bike fit, without concern for compromising performance. Perhaps the most useful application of crank length for bike fitting is in the area of aerodynamics where shorter cranks can open up the hip angle with a low torso position.
In the second portion we will address the factors that most influence aerodynamic drag and explore how aerodynamic drag influences cycling performance. We will begin with wind tunnel data to give realistic ranges of benefits for body position, skin suits, wheels, frames, and other details. We will then explore a number of scenarios using a validated model: Does aerodynamics matter for slower riders? How does drafting affect aerodynamic drag? Does aerodynamic drag matter when climbing? Finally we will address optimizing performance when faced with a “power vs. aero tradeoff”.

Shame a garbage poster has hijacked an interesting thread. But it does show why so many dumb ideas never seem to fully die.

Iif Andrew Coggan thinks I'm just furthering "old wives tales" my reply is that Dennis is the current world TT champ

I do get it that you have studied this concept to a degree that gives you great insight into how to set up a good TT position. I understand! What I'm saying about Rohan Dennis is that he's found the position and crank length that works best for him, or very, very close to it. A couple of things to keep in mind when looking at why he rides in the position he does and why he uses the crank length he does: 1) he's the best TT-er in the world, 2) a pro with great advice from professional advisors who help pro's become better, 3) has come from extensive track background including attempting the hour record, 4) rides his bike about 500-1,000km/week so is used to certain positions more than others, 4) had a bloody tough hill to go up in that world champs TT (so he was not stuck in one position like in the lab).
But my basic idea here is we all should give the guy credit for knowing how to go fast on a TT bike. I think we can agree on that? correct?

And to save me time typing further on here - if Andrew Coggan thinks I'm just furthering "old wives tales" my reply is that Dennis is the current world TT champ, not an "old wife". He's one if the fastest people to ever ride a TT bike. We should be asking what he's doing right!, not trying to figure out what he's doing wrong. I have read Coggan's books a few times, and loved it, but I don't have anything to sell. I do love this forum! And only hop on here when I feel the need to add some input to help all the people who come here looking for information and are in-undated with info/opinions that make them doubt everything about how they go about this sport and want to go out and change everything. Cheers, Scott

I mis understand power is the same as long as you're not 'at maximinum power'

... If you do, I'd like to know about it. If its something you believe without scientific evidence that's fine, you can believe what you want to believe. I'm just looking for studies I might have missed.
EDIT: Its also helpful if I understand why you and others believe longer cranks = more power so I can help dispel those beliefs when I present at ISCO. I presented on crank length to a group of USA Cycling coaches at TTown. Most were really receptive but a few clung to similar cultural beliefs. I am currently using the arguments they made to help refine my talk in Munster. The more of that kind of thing I can address up front the better.
Cheers,
Jim

This is not a research study, but I've seen this page on the interwebs. Looking over the blog page might help you counter bike culture beliefs, at least those that are not supported by evidence. From the looks of it, it appears to be an interesting common-sense argument about crank length and power. That said, I am all for following the hard evidence (which is your dept), but I would be curious to know, do you see major oversights in the logic of any of the argument(s) on that web page?

2) Shorter cranks do not increase the frontal area of the leg as you claim.

Also short cranks need a higher saddle, this increases the vertical component of the legs which the wind sees, it also turns the quad into a big flat cylinder, not aero!

^

Are you saying that moving the upper leg more/less towards the horizontal position at TDC has no effect on frontal area during the pedalstroke?