The crank length thread

[FrankDay]

Frank,

Many of us feel that flexibility is rather unimportant in regards to getting into a good aero position. This from a very aero Jordan Rapp:

"Flexibility is a red herring. If you can touch your knees, you can ride like Dave Zabriskie. Flexibility is rarely a limiter to a good bike position,"

Jordan and I both contend that finding a saddle that meshes comfortably with your nether regions is vastly more critical to attaining and maintaining aero than pretty much any other factor.

http://forum.slowtwitch.com/cgi-bin/gforum.cgi?post=4413231#4413231

Now if your belly is so large that it interferes with your quads while trying to ride aero then that's a whole different problem and one better solved with diet than shorter cranks

YMMV,

Hugh

I guess we will have to agree to disagree on this. Of course, there is zero science on this point. Nothing to support Rappstar's position, nothing to support mine. So, this discussion regarding crank length, aero position, power, and flexibility is entirely theoretical. It would be interesting if Martin were to repeat his crank length study and compare the effect of position and flexibility on power. He did not do this but it would be an easy study for someone to do. Hopefully, someone will.

Anyhow, here is how I see the flexibility issue. Sure, we can stuff pretty much anyone into any position. The question is, can they produce the same power and be comfortable in that position for 5 hours? Forget "touching your knees". Stand against the wall bend over and raise one knee. See if it is easy to get it up to being as close to your chest as it is when you are in the aero position. If it is not easy then it seems to me that you will be losing power trying to push the knee to that position when on your bike. A solution to this would be to shorten your crank so the knee doesn't come as close to your chest. An alternative test would be to put yourself on your bike in your aero position and unclip one leg and then see how easy it is to lift the foot up to the pedal 90 times a minute. If it isn't easy then it is probably costing you power and your cranks are probably too long. We do have some preliminary data that supports that more power is lost on the upstroke with longer cranks compared to shorter cranks but this data does not reach any scientific certainty.

And, I simply don't understand why any saddle prevents or facilitates someone getting into a good aero position. The saddle to me is a comfort issue, not a positioning issue.

Anyhow, until someone does some science on this subject, we are all guessing.

 

[sciguy]

And, I simply don't understand why any saddle prevents or facilitates someone getting into a good aero position. The saddle to me is a comfort issue, not a positioning issue.

Anyhow, until someone does some science on this subject, we are all guessing.

I'd contend one doesn't need to do a study to realize if you are not reasonably comfortable then you won't be able to hold any particular position for very long. This would seem to fall within the common sense category for me.

Hugh

 

[FrankDay]

I'd contend one doesn't need to do a study to realize if you are not reasonably comfortable then you won't be able to hold any particular position for very long. This would seem to fall within the common sense category for me.

Hugh

It does seem to me that it might be reasonable to ask for a study to show that the inability to achieve a good, comfortable, powerful aero position is a problem only with the saddle choice before one made such a claim. Flexibility seems like a much more "common sense" explanation for such problems than saddle choice. But, without a scientific study or two we will never "know."

 

[sciguy]

We do have some preliminary data that supports that more power is lost on the upstroke with longer cranks compared to shorter cranks but this data does not reach any scientific certainty.

Anyhow, until someone does some science on this subject, we are all guessing.

It wouldn't surprise me to to see power lost on the upstroke with longer cranks as the hip flexors are placed in a more compromised position. Perhaps that's why many of the guys riding uncoupled cranks have seemed to gravitate to a very upright position allowing them to open their hip angle. For them, shorter cranks may solve a problem.

 

[FrankDay]

It wouldn't surprise me to to see power lost on the upstroke with longer cranks as the hip flexors are placed in a more compromised position. Perhaps that's why many of the guys riding uncoupled cranks have seemed to gravitate to a very upright position allowing them to open their hip angle. For them, shorter cranks may solve a problem.

Why does that problem only exist for those riding uncoupled cranks? Uncoupled cranks simply expose this problem to the rider. Our original "solution" to this problem was to recommend that they ride a more upright position to open the hip angle while they develop the necessary muscles. Now, we believe this is better solved by using shorter cranks, as that also opens the hip angle without worsening the aerodynamics of the riding position and shortens the transition process. This problem exists regardless of the type of cranks on the bike. It is simply the problem is hidden from the rider using coupled cranks.

I challenge you (or anyone) to find a single study on cycling power that details the subjects position when being tested. Or, any individual data such as flexibility compared to position. Such is the sad state of cycling science that those studying cycling power generation simply haven't considered position to be of any importance that it need even be mentioned, let alone studied. And, those doing bike fitting are simply guessing regarding "best position" as there is essentially zero real science to support what they do. Who knows which ones will be shown to have "guessed correctly" (if any) and which haven't?

Edit: BTW, that photo of Courtney was taken at IM Canada back when he was racing on 172.5mm PowerCranks (and he had the fastest bike split in that race as I remember despite that relatively poor aerodynamic position). When we started thinking about crank length a few years later he did some testing and he tested well down to 110mm crank length but he ended up racing on 145mm cranks. If I remember correctly he won IM WA on 145mm cranks.

 

[CoachFergie]

Why does that problem only exist for those riding uncoupled cranks? Uncoupled cranks simply expose this problem to the rider. Our original "solution" to this problem was to recommend that they ride a more upright position to open the hip angle while they develop the necessary muscles. Now, we believe this is better solved by using shorter cranks, as that also opens the hip angle without worsening the aerodynamics of the riding position and shortens the transition process.

Lets get this straight, you designed uncoupled cranks to solve a problem that doesn't exist which created a problem that requires you to open the hip angle either by raising the bars or shortening the cranks.

Well done, well done indeed!

This problem exists regardless of the type of cranks on the bike. It is simply the problem is hidden from the rider using coupled cranks.

If it is hidden, how is it a problem?

I challenge you (or anyone) to find a single study on cycling power that details the subjects position when being tested. Or, any individual data such as flexibility compared to position.

As Sciguy has suggested it is such a matter of common sense that it doesn't need to be studied. I have performed 100s of bike fits and flexibility has never been an issue. Injury, excessively developed mid-section or fatness are the primary limits to achieving a flat back position on the bike.

Such is the sad state of cycling science that those studying cycling power generation simply haven't considered position to be of any importance that it need even be mentioned, let alone studied.

Then get off your lazy **** and do the research. Just because you manufacture an uncoupled crank that allows adjustable crank length does not preclude you from publishing data in just the same way that myself being a Professional Cycling Coach does not preclude me from conducting research on cycling performance. Although I did have to convince the Ethics Board at AUT of that.

And, those doing bike fitting are simply guessing regarding "best position" as there is essentially zero real science to support what they do. Who knows which ones will be shown to have "guessed correctly" (if any) and which haven't?

What metric do you propose we use to determine any part of the bike fit equation?

 

[FrankDay]

If it is hidden, how is it a problem?

I guess it isn't if your philosophy is "ignorance is bliss"

As Sciguy has suggested it is such a matter of common sense that it doesn't need to be studied. I have performed 100s of bike fits and flexibility has never been an issue. Injury, excessively developed mid-section or fatness are the primary limits to achieving a flat back position on the bike.[/I]

Thanks again for demonstrating the hubris, common in the cycling community (and humans in general), that expresses that something is so obvious there is no need to confirm it. Wonder if science has ever before demonstrated that previously held but untested "obvious" beliefs were wrong?

 

[CoachFergie]

Thanks again for demonstrating the hubris, common in the cycling community (and humans in general), that expresses that something is so obvious there is no need to confirm it.

Yup I have an fat belly but in a sit and reach test can still put my hands right past my feet. My inability to achieve a flat back position on the bike is nothing to do with flexibility and running shorter cranks to open the hip angle up would be a band-aid to the better solution of doing more riding and watching my diet so I an also take advantage of a less weight, more efficiency and less frontal area.

 

[FrankDay]

Here is a germane thread currently going on over at SlowTwitch.

Power difference road to TT bike

a few excerpts:

why is it easier to hit the same power numbers (heart rate 3 to 4 heart beats lower) sitting up right than when in TT position - i have noticed this before on my road bike, almost certainly my functional power is higher on the road bike

Here is what my power tests showed when I first tested myself on both bikes:

20 minute road power tests: ~ 290 average with 175 cranks
20 minute tt power tests: ~ 270 average with 175 cranks

Switched to 165's on tt and my power was instantly ~ 15 watts higher. Mind you I had been riding 175's for over 20 years and had that instant of an improvement.

To give you an example, I lose about 25% power when I move to my TT bike. But, I gain a significant amount of speed by being in that aero position.
Road bike 20 min TT: 320w
TT bike 20 min TT: 255w

Just did an indoor trainer "test". W.U., Computrainer calibration, then 1 hour at 210 W, 87 rpm, alternating 10 mins upright (bars or pads), 10 minutes aero, i.e 3 cycles. Average HR was 122 bpm up, 132 bpm down. Then 1 hour at 240 W, 85 rpm, alternating. Average was 139 up, 145 down. Comfortable , professional bike fit.

I make the same power on both. Hip angle getting too closed is the primary cause.

I really don't understand why so many people think it's a 'given' that your power HAS to be less on a TT bike. Why??

Perhaps the only problem most of these people have is they are using the wrong saddle. What I fail to see here is what is so obvious that those in the know feel it is unnecessary to study this issue. Wait, I forgot, ignorance is bliss.

 

[CoachFergie]

Here is a germane thread currently going on over at SlowTwitch.

Power difference road to TT bike

a few excerpts:


Perhaps the only problem most of these people have is they are using the wrong saddle. What I fail to see here is what is so obvious that those in the know feel it is unnecessary to study this issue. Wait, I forgot, ignorance is bliss.

Cherry picking personal opinions from a cycling forum is so scientific.

 

[FrankDay]

Had a physician customer today who presented another possibility as to why some lose power assuming the aero position as they close the hip angle at TDC. He is convinced some have a crimping of the iliac artery when they get too low, which interferes with blood delivery to the leg. I guess that is a possibility. Should be fairly easy to look at scientifically with the right equipment. I won't hold my breath though.

 

[Boeing]

I like big cranks and I can not lie.....aint no other brother can deny...

 

[FrankDay]

As I have gathered some experience with crank length I have been thinking a bit about bike fit. What I have determined is that (aside from the physical proportions of the athlete themselves) crank length determines everything about the bike fit. It determines the pedal position at BDC which is the basis for setting seat height. It determines the pedal position at TDC, which (along with athlete flexibility) determines stack height. Stack height and seat height determine how flat the athlete is and that flatness determines reach. Crank length even affects the seeming steepness of the frame as shorter cranks move the foot backwards during the major pushing phase of the stroke.

The cyclist interacts with the bike at three locations, the pedals, the seat, and the handlebars. Most bike fitters ignore crank length, doing their fit based upon the crank length that is on the bike that walks through the door. Yet, crank length is just as adjustable as seat position and reach. It seems to me that one cannot do a proper bike fit unless one also knows the best crank length (or range of acceptable crank lengths) for the kind of riding the cyclist will be doing. Ignoring this parameter, it seems to me, is letting your equipment determine your maximum potential rather than finding out what the athletes maximum potential REALLY is and then choosing equipment that helps them to reach that potential. Crank length is one piece of equipment in that equation. It should not be ignored.

 

[CoachFergie]

As I have gathered some experience with crank length I have been thinking a bit about bike fit. What I have determined is that (aside from the physical proportions of the athlete themselves) crank length determines everything about the bike fit. It determines the pedal position at BDC which is the basis for setting seat height. It determines the pedal position at TDC, which (along with athlete flexibility) determines stack height. Stack height and seat height determine how flat the athlete is and that flatness determines reach. Crank length even affects the seeming steepness of the frame as shorter cranks move the foot backwards during the major pushing phase of the stroke.

The cyclist interacts with the bike at three locations, the pedals, the seat, and the handlebars. Most bike fitters ignore crank length, doing their fit based upon the crank length that is on the bike that walks through the door. Yet, crank length is just as adjustable as seat position and reach. It seems to me that one cannot do a proper bike fit unless one also knows the best crank length (or range of acceptable crank lengths) for the kind of riding the cyclist will be doing. Ignoring this parameter, it seems to me, is letting your equipment determine your maximum potential rather than finding out what the athletes maximum potential REALLY is and then choosing equipment that helps them to reach that potential. Crank length is one piece of equipment in that equation. It should not be ignored.

Welcome back Frank, great contribution to the debate. More speculation and opinion. Right back to square one. Way to ignore all the research showing that crank length makes no significant difference to performance or efficiency on the bike.

 

[FrankDay]

Welcome back Frank, great contribution to the debate. More speculation and opinion. Right back to square one. Way to ignore all the research showing that crank length makes no significant difference to performance or efficiency on the bike.

Fergie, could you point me to a single well done scientific study that looks at what constitutes a proper bike fit? I did find this which I think, will not help your cause: http://cyclingtips.com.au/2010/04/science-of-bike-fitting/

Edit: I also found this pdf link from Arnie Baker

Relatively few bicycle fit recommendations are based on solid scientific study. Much of what has been published has been of limited value…

Until then, everything anyone says (including you) about optimum bike fit is, from a scientific perspective, speculation and opinion.

 

[CoachFergie]

This isn't a bike fit thread, it is a crank length thread. Try and stay on topic.

 

[coapman]

This isn't a bike fit thread, it is a crank length thread. Try and stay on topic.

As usual any excuse used to avoid answering a question.

 

[CoachFergie]

As usual any excuse used to avoid answering a question.

Classic Frank Day misdirection should never be taken seriously as should your nonsense about pedalling.

 

[Boeing]

Classic Frank Day misdirection should never be taken seriously as should your nonsense about pedalling.

Classic Kiwi small man syndrome

 

[Oldman]

As I have gathered some experience with crank length I have been thinking a bit about bike fit. What I have determined is that (aside from the physical proportions of the athlete themselves) crank length determines everything about the bike fit. It determines the pedal position at BDC which is the basis for setting seat height. It determines the pedal position at TDC, which (along with athlete flexibility) determines stack height. Stack height and seat height determine how flat the athlete is and that flatness determines reach. Crank length even affects the seeming steepness of the frame as shorter cranks move the foot backwards during the major pushing phase of the stroke.

The cyclist interacts with the bike at three locations, the pedals, the seat, and the handlebars. Most bike fitters ignore crank length, doing their fit based upon the crank length that is on the bike that walks through the door. Yet, crank length is just as adjustable as seat position and reach. It seems to me that one cannot do a proper bike fit unless one also knows the best crank length (or range of acceptable crank lengths) for the kind of riding the cyclist will be doing. Ignoring this parameter, it seems to me, is letting your equipment determine your maximum potential rather than finding out what the athletes maximum potential REALLY is and then choosing equipment that helps them to reach that potential. Crank length is one piece of equipment in that equation. It should not be ignored.

After months....this is what it has come down to? I'm glad it's been awhile since I checked this thread.

 

[FrankDay]

After months....this is what it has come down to? I'm glad it's been awhile since I checked this thread.

Just out of curiosity, do you agree or disagree with the sentiment? You comment adds nothing to the discussion, what little discussion is allowed to happen over the noise of some of the posters.

 

[elapid]

Just out of curiosity, do you agree or disagree with the sentiment? You comment adds nothing to the discussion, what little discussion is allowed to happen over the noise of some of the posters.

Frank - I agree with Oldman. The regulars continue to bicker. It's not worth saying anything, whether we agree or disagree, because it is like an endless loop. You have your opinion and you shoot down anyone that doesn't agree with your opinion because there is no scientific proof to support their opinion. Because there is no scientific data to support your opinion doesn't seem to matter. That's why it is useless for most sane people to get involved with "discussions" with you. Banging my head against a brick wall would be more pleasurable than engaging in "discussions" on this thread.

 

[FrankDay]

Frank - I agree with Oldman. The regulars continue to bicker. It's not worth saying anything, whether we agree or disagree, because it is like an endless loop. You have your opinion and you shoot down anyone that doesn't agree with your opinion because there is no scientific proof to support their opinion. Because there is no scientific data to support your opinion doesn't seem to matter. That's why it is useless for most sane people to get involved with "discussions" with you. Banging my head against a brick wall would be more pleasurable than engaging in "discussions" on this thread.

Then, why comment at all? "Shooting down" others with different opinions is simply making counter arguments supporting my view. Do you really have a problem with pointing out that there is zero scientific support for some of the "generally accepted" views that are put forth in a supposed "discussion" of this topic? Would you have a problem in a discussion of evolution if I pointed out that there was zero scientific support for the Bible's concept that the universe is 8000 years old if someone raised that as an alternative view? People don't like having discussions here (and elsewhere) when their bias is confronted and it is apparent there is little scientific support for such views. I, at least, am able to admit that I cannot prove my hypotheses but I believe there is a good theoretical basis for presenting (and discussing) them.

 

[elapid]

Then, why comment at all? "Shooting down" others with different opinions is simply making counter arguments supporting my view. Do you really have a problem with pointing out that there is zero scientific support for some of the "generally accepted" views that are put forth in a supposed "discussion" of this topic? Would you have a problem in a discussion of evolution if I pointed out that there was zero scientific support for the Bible's concept that the universe is 8000 years old if someone raised that as an alternative view? People don't like having discussions here (and elsewhere) when their bias is confronted and it is apparent there is little scientific support for such views. I, at least, am able to admit that I cannot prove my hypotheses but I believe there is a good theoretical basis for presenting (and discussing) them.

Frank, you don't seem to get the point that there is no such thing as a discussion with you. So-called discussions with you are an endless loop - they involve you presenting your opinion and then continuing to present that same opinion over and over and over. The biases you so freely accuse others are the same biases that you ignore in yourself. You continually bemoan the lack of scientific investigation into crank length, but don't seem to realize that the majority of others don't share your interest/passion. Hence it is up to you to design and conduct this study. Put up or shut up as they say.

The multiple threads and tomes of pages on crank length are proof of your "discussions" and validate why so many members on this forum think this and similar threads on this topic are black holes. There is no discussion when you are involved because you don't know how to discuss.

 

[coapman]

Then, why comment at all? "Shooting down" others with different opinions is simply making counter arguments supporting my view. Do you really have a problem with pointing out that there is zero scientific support for some of the "generally accepted" views that are put forth in a supposed "discussion" of this topic? Would you have a problem in a discussion of evolution if I pointed out that there was zero scientific support for the Bible's concept that the universe is 8000 years old if someone raised that as an alternative view? People don't like having discussions here (and elsewhere) when their bias is confronted and it is apparent there is little scientific support for such views. I, at least, am able to admit that I cannot prove my hypotheses but I believe there is a good theoretical basis for presenting (and discussing) them.

The more you shorten your crank length, the more you reduce your range of gears on the higher side. Is that true?