It is just this kind of "problem" that Tom's trip to the wind tunnel will help to answer. Since Tom rides PC's I think he will be attune to answer these questions when he gets back, i.e., just how much can we open the hip angle without hurting aero too much. Sounds like you have a good compromise, keeping your speed the same but improving efficiency to save your legs for the run.

Be nice to hear from others what they are doing.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

I'm a bit confused which is understandable since I haven't tried these things yet. I was under the impression that they were a training tool. Do people actually race on these things?

I could understand training on PC's on one of my road bikes but for the tri I'd get on a tri bike in a steeper aero position with regular cranks. Is this not standard procedure?

Most people still train on these and race on regular cranks. Some are starting to race on them for many various reasons, the most important one being that people find themselves faster on these than on regular cranks apparently because regular cranks will let them slip back to less efficient pedaling style when they start to get tired. But, either way, I think what people like Tom in AL are finding is that they are faster and more powerful on the PC's if they adjust their position to get slightly less aero but a lot more power. This should be their fastest position on regular cranks also as, when pedaling properly on the PC's one cannot tell the difference between PC's and regular cranks.

It makes no sense to me to train one way then change postions and race another, especially if that other way forces one to pedal in a less efficient fashion. Sort of like wearing new shoes (that cause blisters) on race day.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

How much one individual can "sit up" for better power could be different than the next person. It depends upon their initial positioning for one thing, how comfortable they are, whether they are in fact more powerful (just because they feel like they are doesn't mean they are), etc.

I am faster on PCs, but only after I get tired... I assume it is because I begin to waste potential drivetrain energy lifting the rising leg as I tire on regular cranks. I am always faster if I am standing going uphill with PCs, I think for the same reason...wasting potential drivetrain power from a less efficient pedal stroke when on regular cranks. All bets are off when my hip flexing muscles are fatigued, though...which now usually only happens on long straights, or into headwinds, when I'm trying to get more "aero".

When (and if) I have adapted well enough to not tire out in my more "aero" position, I might race on them on longer races. I don't know if PCs would give me an advantage on shorter races, because I seem to be able to keep my new, improved, more circular pedaling technique throughout the shorter races...and it makes setting my shoes up for the transition easier on regular cranks.

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Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)

Interesting article. Where it falls down regarding this discussion is it assumes power is constant (varying only on the ability level of the rider) regardless of position. When one has trained a little bit on the PC's this is clearly not true. So the problem becomes what is the best position to optimize the power/aero combination. This article does not address that problem - at least I didn't see it.

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Frank,
An original Ironman and the Inventor of PowerCranks

You were right, it was there ("If done badly, maybe, but if done well, no. Recently, Heil et al., (MSSE, May 1995) have investigated this question, and the results tend to show that your cardiovascular stress for a given power is increased by decreasing the trunk to femur angle. therefore, if you lower your elbow position, you may need to move the saddle forward to maintain your trunk to femur angle while getting a lower, more nearly horizontal torso position.") and it goes to exactly what I have been saying. Unfortunately, to say that it changes and can be fixed by simply moving the saddle forward I think minimizes this important variable. It may really be a small change but I don't think so and it may vary quite a bit between people. And, one can only move the seat so far forward and stay within the rules.

If one went to a wind tunnel and got drag numbers for various positions (instead of simply finding the position giving the lowest drag) then one could later do power analysis at these various positions and calculate which should be the optimum position for various conditions. This would be useful information for the serious athlete.

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Frank,
An original Ironman and the Inventor of PowerCranks

Seems to me that if I had data that told me aerodynamic data for various positions it would then be possible for me to attempt to assess the variability of power associated with position within myself and assess that variability over time as I train and get better and then make a decision as to what is best for me as opposed to taking the advice of Jim Martin, who may understand both aerodynamics and physiology in general but not the specifics of these physiological concerns as they relate to me. I would think others who are interested in optimizing performance would have the same concern. Jim Martin in his paper states this is a concern and then ignores it. A pretty good paper regarding aerodynamics (which was its purpose), not very good advice regarding the physiological interaction of power with position and the effects on speed.

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Frank,
An original Ironman and the Inventor of PowerCranks

One can only come so far forward as the superman position has been outlawed. Power does vary with hip angle, Martin and you admit this. While it may vary only slightly in elites (which is your assumption but we don't know), this may not be the case in us mear mortals. Further, aerodynamic changes may vary only a little also. One doesn't know unless one measures. And, while principles can be established from testing in others (probably more valid for aerodynamic testing than power testing), the individual doesn't know what their own personal changes are unless they are measured. It is easily possible for the individual to do their own power testing. Now with on bike power measuring devices it may also be possible for people do do their own "aerodynamic" testing, albeit this would be a lot harder to do.

Either way, unless one knows how BOTH power and aerodynamics vary with position in a particular individual, one cannot determine optimum positioning for sustained time-trial speed. For the very serious athlete or coach to ignore one component of this issue is foolhardy in my opinion.

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Frank,
An original Ironman and the Inventor of PowerCranks

I thought superman had more to do than with just arm position but opening hip angle also by moving forward. If I am wrong then it was a poor example.

I didn't say that measuring this stuff was easy and interpreting it may be even harder. Because it is not easy, one way to approach the problem is to ignore half of it and put yourself in the most aero position and train to power in that position per Obree. But, even Cobb doesn't recommend that as I understand he at least looks at how breathing restriction might affect power and modifies recommended position (not necessarily going with the most aero wind tunnel measurement) as a result. I don't think the Obree (ignore it and it doesn't exist) approach is optimal but it may be the most practical approach for ordinary folks with limited finances in view of the difficulties.

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Frank,
An original Ironman and the Inventor of PowerCranks