The local bike shop is an evil villain… *always* talking people out of the correct crank length or a Eric Reid AeroFit.

<shrug>

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Male pro road racers and triathletes are two completely different animals doing totally different sports. Not good to compare.

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Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Elite athletes use elite crank lengths .

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Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Yes, three phenomena:

1. Elite athletes use what’s available
2. Elite athletes use elite crank lengths
3. Elite athletes are the last to know

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“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Are you finding power losses across the spectrum or just at threshold? The benefits of short cranks usually outweigh any perceived losses for long course races at submaximal efforts.

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Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

I would add that elites are typically bound by sponsorship, so whats available to them is ironically less than whats available to amateurs. Half the pro peleton is still using Shimano power meters although it's well known they have significant big/little ring measurement disparity.

Is there any evidence (anecdotal, peer reviewed, or otherwise) that shorter cranks have no benefit, negative benefit, or less benefit, on shorter courses like, say, a 40 km TT at near maximal effort?

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I wouldn’t frame it that way. Stop saying “shorter” and start using “optimal”.

Everyone can be on optimal length cranks, but only elites are on elite crank lengths.

IOW we should copy elites because of their optimalness, not because of the length.

In my personal work, I see 10% like shorter cranks and increase power, 80% like shorter cranks and have no power change, 5% dislike shorter cranks despite positive or neutral power, and 5% dislike shorter cranks and have a loss of power.

My theory is that when you’re riding at 65% of FTP, you can have whatever position you want, ie the most aerodynamic one, so the longer the race the lower you go, which is counter intuitive. IOW your power usage spectrum is not linear. Your position or cranks might cost you 5% of FTP but 0% of IM power.

YMMV.

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I understand this reply, but your earlier post seemed to imply that the optimal crank at near maximal efforts for shorter distances (like 40km TTs ?) is longer than the optimal crank for IM distances?

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Just like optimal cadence depends on power output and duration of effort.

Excellent. So what is the relationship? Relationship to power output? Relationship to duration of effort? Direct relationship, inverse relationship, other?

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Beats the hell out of me... but I bet you'll find more people at long duration- lower power efforts liking shorter cranks and lower cadence. The little guys pushing 400W in pro TTs are spinning pretty fast and almost lifting off the saddle already, so unless they have impingement issues, shorter cranks aren't going to make a lot of sense. Also IMO, short cranks do not feel "right" climbing hills, and it probably would be a bad idea to change too much between road and TT.

I'd expect it to also depend on femur length, foot length (?), whether a person's muscles work better at greater motion- less force- lower cadence, or lesser motion- more force- higher cadence.

Lots of wee little factors that can contribute.

Yes - the bicycle/human interface is actually very complicated (the gazillion variables I referred to in my first post), with many things interrelated, which is why I question simplistic solutions, especially for us without access to a wind tunnel.

You switch from 170's to 165's and do a PB. You sure your seat wasn't 5mm to high to start with? Oh, you raised your seat 5mm at the same time. Guess what, you just dropped your bars 5mm - you sure that's not it? Maybe you're just having an exceptionally good day...and on and on!

In the mean time, I put the 170's back on my bike (from the 165's), seat back down 5mm, and did 25 miles into a strong headwind. My legs feel much better! Is that simplistic enough? :) :)

comparing pro TTs to triathletes is like comparing American football to European football... they're both football but they're two totally different sports. Lots of wee factors contribute but one of the wee factors is decisive... aerodynamic drag.

They only thing that's comparable is the concept of "optimal" for the demands of your sport, your physiology, your morphology. The reason is because a) UCI TT bikes are limited by UCI rules and b) UCI TTs are supramaximal whereas most triathletes on here are doing submaximal efforts while intending to run fast off the bike. Both can have "optimal" positions.

Bottom line it's about comfort for triathletes. Comfort begets aerodynamics and power in triathlon with a proper bike fit. What everyone calls "high hands" is really my "open shoulder angle" concept which is more aerodynamic, more powerful, and more comfortable.

UCI riders work for their bike, because their bikes are fixed. Tri bikes work for their triathletes (or should) because they are changeable in many degrees of freedom. This is what LBSs and lower case bike fitters don't understand, and why capital "B" bike fitters have a job. Bad bike fitters make athletes work for them, good bike fitters work for their athletes.

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

In my case, my position with my previous cranks had me right at my limits: as low as I could get, and right at the limit of hip and knee angles. Going to a shorter crank allowed me a lower more aero position, while at the same time opening up those angles. More comfort, more power, less drag...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

This is my "Big Lebowski" theory of bike fitting... the cranks (rug) tie the whole fit (room) together.

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Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Several sites, GCN, Dylan Johnson (the best) to name a couple have tested longer, shorter, spinning, grinding etc etc and have all come to the conclusion, with real numbers, that you perform pretty much the same no matter the crank length or how fast you spin. And now that TT positions are relaxing because width trumps height and gives better power, the advantage of shorter cranks is questionable. I have gone backwards and forwards from 170 to 175 really can't tell the difference.

Go with anything you already have.

Try 150... you'll tell a difference. Maybe not in speed, though...

I used my bike on the track for a while and so I put on a set of 165s for pedal strikes and also to deal with instances of very fast cadence. I'm now back trying to be a triathlete and left them on as I converted the bike back to a geared TT bike.

I feel like I've got my position dialled now and I love the feeling of the 165s. Also I think my decent run off the bike is partly due to them as well. But I find the handling of the bike a bit sketchy and am contemplating sticking on my 175s just so I can lower the saddle and bring my centre of gravity down. I'd like this for some of the more fast/technical descending in some of the races I do.

For people that have switched between cranks a bit, do you notice a difference in the centre of gravity when raising/lowering the saddle?

I don't want to ruin what feels like it is working for me in triathlon.

This is why I switched from 170's to 165's on my tri bike. I was able to get into a more comfortable and lower position. That was last year and I love the 165's on my tri bike. I then switched my roadie to 165's thinking it would be a great idea and it felt like crap. Those cranks are for sale in the Classifieds now, and I went back to 170's on my roadie.

Didn't read the whole thing because too long, but here's my case. Used bike I bought came with 172.5mm crank(bike size is Cervelo P2 51cm). I had no clue about crank length and I thought whatever came with the bike is all good and correct. I saw someone's post on here about the shorter crank, I was curious, so switched to 165mm. I PRed my bike time at 70.3 and I think run feels much easier. I will NOT go back to the longer crank.

What's your height?

I am not a believer in the instant "Ah Ha" moment other's have commented on, but rather, a believer in how something feels after many miles and time in the saddle. Only then, IMHO, can you really pick up on ALL the subtle ramifications (good and bad) due to a change in position.

I'm 5'7 and ride Cervelo tri bike size 51, Felt bike size small, Trek 52cm. I've done so many 70.3 races before I switched to 165, so I can tell my bike has improved after I went for the shorter crank.

At 5' 7'' you probably should not have been on 172.5mm cranks, even prior to the "short crank" revolution.

I didn’t know any better. Glad that I ran into one of the posts on here. That’s when I started looking into it.