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Anyone with an FTP above 350w using short cranks?
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Just a question as per title.

I'm determining short as 160mm or less.

Currently doing some testing with a range of athletes including a few pro cyclists and we are finding an interesting relationship between power output in AERO position and minimal acceptable crank length.

Please note this is in AERO position and is OUTSIDE.
Therefore has no relationship with the studies on crank length done sat up on an erg.
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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?
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Re: Anyone with an FTP above 350w using short cranks? [grumpier.mike] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [turdburgler] [ In reply to ]
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Cool, have you tried anything shorter? 160 seems to be a bit of transition point.
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [Ai_1] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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TriByran wrote:
Just a question as per title.

I'm determining short as 160mm or less.

Currently doing some testing with a range of athletes including a few pro cyclists and we are finding an interesting relationship between power output in AERO position and minimal acceptable crank length.

Please note this is in AERO position and is OUTSIDE.
Therefore has no relationship with the studies on crank length done sat up on an erg.
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")
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [Hesiod] [ In reply to ]
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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?
Last edited by: TriByran: Feb 26, 19 7:15
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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TriByran wrote:
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.
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.
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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TriByran wrote:
Cool, have you tried anything shorter? 160 seems to be a bit of transition point.

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.
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [turdburgler] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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.


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Re: Anyone with an FTP above 350w using short cranks? [Hesiod] [ In reply to ]
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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?
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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TriByran wrote:
Please note this is in AERO position and is OUTSIDE.
Therefore has no relationship with the studies on crank length done sat up on an erg.

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
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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TriByran wrote:
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.

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.

-------------
Ed O'Malley
www.VeloVetta.com
VeloVetta is developing AERO cycling shoes with CFD and wind tunnel testing.
InstagramFacebook
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Re: Anyone with an FTP above 350w using short cranks? [Ai_1] [ In reply to ]
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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..
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Re: Anyone with an FTP above 350w using short cranks? [Hesiod] [ In reply to ]
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Hesiod wrote:
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.

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

-------------
Ed O'Malley
www.VeloVetta.com
VeloVetta is developing AERO cycling shoes with CFD and wind tunnel testing.
InstagramFacebook
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Re: Anyone with an FTP above 350w using short cranks? [Bio_McGeek] [ In reply to ]
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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?

-------------
Ed O'Malley
www.VeloVetta.com
VeloVetta is developing AERO cycling shoes with CFD and wind tunnel testing.
InstagramFacebook
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Re: Anyone with an FTP above 350w using short cranks? [TriByran] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [RowToTri] [ In reply to ]
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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.
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Re: Anyone with an FTP above 350w using short cranks? [Hesiod] [ In reply to ]
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Hesiod wrote:
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!

-------------
Ed O'Malley
www.VeloVetta.com
VeloVetta is developing AERO cycling shoes with CFD and wind tunnel testing.
InstagramFacebook
Last edited by: RowToTri: Feb 26, 19 10:21
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Re: Anyone with an FTP above 350w using short cranks? [RowToTri] [ In reply to ]
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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?
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