Big people are more likely to be able to achieve that power number and crank length is just one lever arm among many when pedaling. so I would think height would think height would be more important than FTP.

I don't really buy the argument that crank length and chain ring don't matter because a super short crank (100 mm) or are really weird chain ring shape would be pretty much impossible to maintain a similar power output. I will be interest ti hear what you find

Not quite but close. 339 watts avg power on TT bike last week for 65 minutes. Later in the year it will get closer to 360.

160mm cranks. What specific questions?

Interestingly there is an interaction with leg length, although it definitely isn't as clear as it would appear.

So far we have found, zero riders with FTP over 350 choose short cranks, as they get higher their dislike of them appears greater.

However all of these riders were happy enough on 165s, apart from the guys with FTPs over 400.
For these 170-175 felt optimal.

Leg length was a factor in that athletes with FTPs of 300-350 but with longer legs struggled with the short cranks, but were ok on 165s.
We had athletes at lower powers with long legs fine on shorter cranks. (150-160).

We are currently doing some torque analysis, but it seems to related to the ability to apply a considerable amount of torque at an appropriate cadence in a constrained position (aero). With the short cranks the window is smaller, which only seemed to have a significant effect once we were getting into high power realms.

Cool, have you tried anything shorter? 160 seems to be a bit of transition point.

I think in order to make this useful and revealing you'll need to find a way to normalise your data. Perhaps that's where you're trying to get to with your testing, but it seems odd to throw out the question posed by this thread in that context.
It seems extremely unlikely that either 350W or 160mm are magical numbers. It's far more credible in my view, that there is a parameter or parameters, linked to power and crank length which is responsible for any pattern in preference or ability, and until you figure that part out, any data gathered will be of very limited predictive or diagnostic value to other cyclists.

The rational for asking the question was to help us decide whether to continue to collect data.
So far we haven't had any real FTPs over 350 that have happily settled on shorter cranks.

Slowtwitch has a huge body of athletes, so we wanted to poll to see if these indeed exist and if they do, then we will continue to collect.

We currently have a load of white swans, but I want to ensure we aren't missing any black swans out there.

FTP around 360, and still riding with 175mm cranks. I tested shorter cranks with Jim @ Ero back in the day when it was still called Final Fit, but we decided the 175mm was better because it gave me a better power output. (I'm 6' 1")

My ftp has been consistently 340-360. Off season around 340. When training smart, 360. Crank-length is 145. Avg cadence when riding at ftp is around 83-85.

For reference, I’m 5’9” and 150lbs.

Cracking thanks.
You're quite short, whats your leg length?

Presumably with that power and weight you're at a pretty high level?

Also, just to check what power meter are you using? and can you put out that FTP in aero position?

I think you're missing my point. how do you know your black swan isn't a smaller athlete with <350W FTP or a very long limbed one with >160mm cranks (assuming cranks scale with the athlete's proportions). The fact you're asking about 350W and 160mm seems to indicate you don't understand your data yet. Which is fine, if your analysis is still in progress but not a good place to stop. Thus my comment. I would think if you already have good data, it's time to start analysing it and let that tell you if it's time to stop gathering data, or if your data is intentionally or unintentionally biased, in which case your test protocol may need adjustment.

Let me put it this way. Proper testing starts with a plan rather than just gathering "data". Such testing would not be influenced much by the responses to a thread asking if anyone else had different results. The suggests a lack of confidence in the validity of the chosen test subjects or test protocol. Such information should be considered while planning the test or while analysing the data. It shouldn't direct the testing. From a scientific standpoint I believe that is inviting bias and undermines your work.

Below 160mm just didn't feel right to me although to be fair I didn't spend a terrible amount of time acclimating. Interesingtly I had no problem putting out similar power on the flats below 160mm, but rolling and going uphill my power suffered. I felt like I lost some ability to generate torque. Again, I spend a week below 160mm (want to say they were 150mm). I have no power loss anywhere between 160mm - 172.5mm cranks on the TT bike. I always can produce about 10 watts higher on a road bike, so my experiences I'm sharing are all specific to my TT position that is sustainable for 4h30.

181 cm tall. In seam length is 79cm. ~68 kg.

Inseam for leg length is 31”.

Power meter right now is vector 3. I’ve also used power tap rear hub and a power tap chainring. Ftp is a wee bit lower on the hub, but pretty much the same on chainring as pedals.

Yes...ftp in aero outside.

But... I do at least 90% of my riding on a lemond trainer inside. I don’t do much ftp specific stuff...and test it only a couple times a year at most. I do one day a week with super hard shortish intervals (4x3 mins at 120%, 3 min recovery) one day at 2x20@90% and one long ride 4hrs—with 6x10 at 90%, 3 min rest, and then 6x3 at 100%, 10 min 70-80% recoveries. If I don’t feel it on the 2x20 day I don’t stress about it. Just do a recovery ride instead...or take some caffeine and harden up. Some days I find the drive and some days I don’t...

Other days are recovery rides at 60% or less for usually 75mins.

When I first went to 145s I spun at avg 102 for about six months. But I’ve slowly found a more powerful and sustainable effort in the low 80s. When doing z2/3 I spin around 90.

Hi, I do not have 350 but I'm not far either.
2 years ago I had 175, but because I had it on the TT since it was used.
go to 172.5, go to 170, and with all the reading that I find, get excited for a 165, buy a new rotor crankset.
With much desire the potentiometer passes, installs and went out to roll, first very strange sensation.
I gave him a month, with all the desire and wanting outside what was supposed to be.
I gave him 2 months.
I could not with her, or maybe my head from the beginning felt bad and already said no.
against wind and ascent I was not happy, something was missing, I would not know what to tell you, it was like an extra fatigue in the main muscles.
Then I had to buy 170 again, we talked about nothing 5mm more.
And from then until now I'm doing very well, but I still want to be able to one day give back the opportunity to about 160 to have a good position and more comfortable.
But I keep my head with what happened to me.
And something still stops me from going for them.
I know this much not to contribute, but I do not think I bother my comment to anyone
my height is 175 cm, insane 79.5 cm

sorry my english.

I agree with Ai_1. Knowing the interaction of crank length, specifically with the TT position, I'm trying to wrap my head around a reasonable experiemental design to determine a valid rider PREFERENCE.

Rider preference is wrapped up in their belief system.
TT position, especially outdoors, is wrapped up in comfort and familiarity and handling characteristics.
Optimal power might take an adaptation time.
Leg length variation may/will affect all of this.
Body mass will affect total power, would watts/kg be a better measure?

So, how does one control for all these variables in psychology, physics, physiology, mechanics, and adaptation (and others I'm not considering off the top of my head) in some reasonable time frame with enough variance in subjects, and some method to manage the placebo to have meaningful implications?

That seems like a really tough nut to crack. And there hasn't even been a question about the overall impact on aero that the positional changes from shorter/longer cranks might have for a particular morphology.

5 minutes for a fit session, and 30 minutes on the road per crank length, per rider with a thumbs up/down isn't going to cut it.

Very interesting thank you.

Presumably you have pedalled outside at that power in aero for a full hour or close to?

With those numbers you are presumably racing at a high level?

Exactly right! Those studies by lab-coated geeks may not be compromised by the power-aero trade off which occurs with tight hip flexion angles. So those studies that show no difference are probably wrong for riding OUTSIDE in AERO position. Once the power-aero trade off comes into effect the advantage goes to the shorter cranks.
The fact that elite riders like what they're used to is likely psychological and cultural, not biomechanical or physiological.
Good for you for asking these important questions!
Cheers,
Jim Lab-Coated Geek Martin

What is "appropriate cadence"? Does it get higher as crank length gets shorter?

I also think that you need to include some metric for the appropriateness of the short crank to the fit of the rider. I would not be surprised if in the population of your riders, as FTP goes up, height goes up and therefore the usefulness of a short crank for fit goes down.

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Ed O'Malley
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Founder of VeloVetta Cycling Shoes
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The fact you're asking about 350W and 160mm seems to indicate you don't understand your data yet. //

I tend to agree with you here, a guy with a 37 inch inseam and riding 175's could be effectively riding very short cranks(for him) I think it should be obvious that more people are not riding that power with 160's is that bigger(and taller) riders just put out more power in general. Smaller riders who are riding 160's or less will traditionally put out less power, but of course may go as fast or faster because they punch a smaller hole in the wind. Seems like at the very least, height(and really leg length) should be taken into account in this discussion and data collection..

Holy leg strength, Batman! Dude... you are putting some impressive force into those pedals!

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
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Are you the Jim Martin that did a study comparing power output of stiff cycling shoes and clipless pedals vs. running shoes on flat pedals?

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
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Last HIM I did I held 312 for 2hrs. Fastest bike split. Haven’t done halves for a couple years now. Last full I did I held 260 for 4:15ish. All pretty much in aero.



I don’t race much. Will race this year in September.

I’ve been on 145s for about 4 years I’d guess.

I don’t think crank length matters as much as people whine on here. It’s mental. You adapt to whatever you decide is normal. The body does what you constantly ask it to do and...provided a minimal amount of attention to what you’re doing, over time things will settle to normal.

I went shorter to ride more aero. Drop my front end, lift my back end. And open my hips. I feel comfortable in aero and my knees don’t smack my belly.

Ha. I don’t know about that...

But at intervals over 400 I tend to reduce cadence to around 70. Just grind it out.

Do you think a a couple cm’s makes any real perceptible difference? 145 to 165 seems like no big change.

So if you were able to apply constant force to the pedals all the way around the circle...

145mm cranks, 80 rpm, 350 Watts requires 288 N or 64.8 pounds-force on the pedals (both legs combined).

172.5mm cranks, 90 rpm, 350 Watts requires 215.3 N or 48.4 pounds-force.

Pretty big difference!

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
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Ok. Those are big differences. But I think I’d be working really hard to get 170’s around to the power phase at 90rpms.

Is there a way of taking into account that we all mash through the power phase...even when we are trying to be smooth? I feel like I’m coming around quicker and easier on short cranks and getting to the mash with less work. Idk. I have no science to the madness...but I am conscious of applying power for a little spurt. I get a smooth rhythm. Short cranks feel like less work overall...

How does that fit with the numbers? Does not applying equal pressure change the overall efficiency?

Agreed. I'm 6'3" and ftp near 350 and tried moving to shorter cranks and felt like I was throwing away the natural leverage my long legs provide. The wider the diameter, the less force you have to apply at any given moment, delaying fatigue. If the crank length better fits your natural stride length, then your effort is easier because it fits your body geometry. But if you try to cram in smaller rotations, then you have to generate more torque to get a rotation, which is throwing away the longer levers you are carrying on you already - Like running short steps with heavy shoes for no reason. If you are going to put weights on a flywheel, put them out at 175 cm instead of 160 cm to get more power out of the system more easily. But as pointed out, you first have to have enough breathing room (engine compartment, height) to let a 175 cm flywheel spin freely under the air intake (lungs) in the first place. By the time you get up to 6'3", your chest in aero is clearing that flywheel pretty good. A beer gut becomes a bigger problem than crank length.

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At one point some years ago we were interested in bike shoes with only half the sole being stiff. Pearl Izumi made us a pair and we got some pilot data but we never did a full study.
Do you have a link to the study?
Cheers,
Jim

I suspect you are right that you would have difficulty turning 170's at 90 rpm as most people naturally have lower rpm as crank length get's longer because I think most people apply close to the same force to the pedals when they change crank length - rpm adjusts to keep power the same. Sorta.

To do the analysis on "mashing" vs. perfect circular pedaling would take more time than I want to put into it - probably could do a simulation in engineering equation solver or something. It might change your metabolic efficiency (i don't know) but it will not change mechanical efficiency. Pedaling style can also affect how many muscles are used, at what % of their maximum force they are being used and therefore affect muscle fatigue while aerobic cost remains the same.

But even with mashing, the relative difference in pedal force will be the same.

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
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No - Philip Majure (formerly of Pearl Izumi) was telling me about it though. I would love to see it. I'm working on a shoe/pedal system right now for an athlete to use in the mixed relay in the 2020 olympics and I would love to see that data....

Edit: though really what I'd like to see is if a running shoe midsole between the foot and a stiff pedal hurts power output. I found one study on that but it was at very low power levels.

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
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Damn you!

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https://connect.garmin.com/modern/profile/domingjm

I had a foot injury and switched to running shoes on big flat pedals on my trainer rides for a year and power was exactly the same after just a couple of rides getting used to it. On top of that, there was a big benefit on longer rides, where not being locked in allowed me to adjust front/back on the pedals and saddle all I wanted to remain comfortable. It has a lot of endurance benefits for 112 miles and then running, which won't show in a study looking at just power at the pedal. My experience shows that people should try it if they feel the need. PM me and I can dig up the pedal details I used.

Thanks! this will be for a very short (5km), very hard bike ride! And then a very fast 2km run after. There's no off the shelf pedal or shoe that meets the athlete's requirements, so we are working on a system to see if we can come up with something that works.

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

First you say this:

I don’t think crank length matters as much as people whine on here. It’s mental.

And then you follow up with this:


I went shorter to ride more aero. Drop my front end, lift my back end. And open my hips. I feel comfortable in aero and my knees don’t smack my belly.

So which is it, mental, or all the physical things you listed?? (-;

My threshold was about 375 when I rode 355watts for a hot 40k time trial on 155s. I had played with crank length for years. On my 785mm seat height on those 155s, I was equally happy on 160s, but did not feel correct after repeated trials on 150s. Getting down to 165 from 172.5 was a huge improvement. And 160mm was definitely better than 165mm.

My understanding of those particular crank lengths for myself came about from doing repeated (like everyday) threshold sessions on my fit bike and changing crank lengths OFTEN. The more you change them, the more tuned in you become to the effects. I knew if I was feeling fresh, the 160s would feel better, but if I was fatigued I liked the 155s better that day.

You can have too much knee flexion at the top of the stroke, so you shorten the crank. You can also have too little flexion, so you have made the crank too short. There is a range of crank lengths that the majority seem to fall into as a function of their seat height, but mitigating factors can indeed include FTP, with stronger riders tolerating longer cranks a bit better, while still generally trending to shorter than stock sizes.

I have not fit anyone who has chosen over 165mm in a long time. Including an 88cm seat height / 400 watt FTP pro on 165s, another 83cm seat height 360 watt FTP pro on 165s. You just gotta have a process that involves the rider, helps them find their positional limit, and zero in their awareness and your eyeballs on the specific areas and angles that are limiting further position improvements. Then maybe crank length helps solve some of those problems.

You have to be able to achieve and recognize when a rider is at basically the hip angle / thigh to torso / knee flexion limit of their existing crank. If you can't do that, there is probably no "a-ha!" moment for the rider when changing cranks.

Do I contradict myself? Very well then. I contradict myself. I contain multitudes.

It’s mental refers to the idea that it is harder or easier. I take that as a perceived difference. However, physics apparently differs from my theory and indeed it does take more force to move a shorter lever. So I’m wrong.

As for the physical benefits. I also bet I’m not any more aero than I was with longer cranks. I suspect I would benefit from small and careful attention to aero details a great deal more than I do from playing around with crank lengths.

I also bet I’m not any more aero than I was with longer cranks.//

Well, what crank do you think is more aero all things being equal, the longer one or shorter one? And the things you do when you shorten cranks have a tendency to make one more aero, so there is that. You dont have to think about it, you just do it and there you have it, flatter back, perhaps better hole punched into the wind up front, and you can ride it longer, all aero benefits..


So I would take your bet...(-;

I like 165 personally.
I found 155 just a little too short for my gargantuan legs (37 inches) I found they just felt too punchy, I used them for a year, including an Ironman with a top 10 bike split. But I could never make them work for harder sustained efforts around FTP
I’d like to trial 160 at some point

Small world! I'd still like to do something with it. Need to find an undergraduate who's keen on cycling.
Would like to get a size run of some brand of shoe, Chucks maybe. Figure out a way mount cleats on em and them compare with standard stiff cycling shoes. I wouldn't expect to see any difference in max sprinting power.

Without quantifying the weight of the person you are not going to gain much unless that is really part of your study that absolute watts matter. Fwiw, I have had an ftp of 5.14 w/kg at least during my peak, right at your 350 target at 68kg. I ran cranks as low as 115mm. 115 was a challenge for different reasons but there was no discernible drop off in power. I didn't like them for climbing however. Didn't spend much time on 115s but 145 were much more doable. I am a huge fan of short cranks for everything, road, tri, MTB.

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Thanks Thomas, what’s your leg length?

I found what worked great was lightweight but really large and super flat downhill mountain bike pedals like these. And then trail running shoes for the stiffer soles. You get all the stiffness of being locked in with bike shoes, but the freedom to move around all you want. It's amazing.

I did it to help get over plantar fasciitis and it worked great. I was able to keep riding and racing and move my foot around as needed to relieve pain as it developed. I won a local 100 mile gran fondo on flat pedals and running shoes, same power as the year before, no problems. It was funny getting off the bike and walking around to get beer like a normal person, no clack-clack like the "real" cyclists. ;)

I'm back on clipless now, but for no reason in particular.

I was 5 feet 8.75 with an inseam of 33.63. But I somehow "grew" in the last 18 months and I am closer to 5 10, haven't measured my inseam to see if it changed at all. I never did any aero testing, mainly because it was a PITA. I did the adjustable cranks via PowerCranks that allowed me to play around with it. I did slap aerobars on the commuter bike for a short while. I really like the 160-165mm range.

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Lol...you couldn't just round that to 9, and 34 (or 33.5)?

I have nothing else to add.

Ha! Thanks...I guess. ᕦ(ò_óˇ)ᕤ