Not a PCer wrote: "As long as your hip joints are fixed in space relative to the bottom bracket, it is impossible for upper body movement to either add to or substract from power output."

Glad to see we are back to disagreeing. I think hip angle has a lot to do with power application. It may be that the explanation as to why power increased while standing is related to hip angle, which is more open while standing. Decreasing hip angle decreases power. The only reason it is of any benefit is because it improve aerodynamics such that the overall effect is, typicaally, more speed. Not a PCer would understand this implicitly if we could only get the Not off of his moniker.

One more thing. The angle of concern regarding affecting power is the angle between the femur and the lower spine, not the clavicle.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

Rats :-) Another missed opportunity for the lurkers out there.

Then I misread the original question which I thought went to power vs hip angle. I agree, if the elbows are on the aero bars, the butt is on the seat, and the feet are on the pedals, then all of these angles are essentially fixed for one pedal rotation, although there is lots of room for tweaking the angles by varying crank length, seat height, and aerobar position, which is where the art of fitting comes in (it is an art isn't it?)

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

The place that I get clavicle from is from Dan's fit page:

(A NOTE ON MEASURING ANGLES: Finding the proper point on your shoulder can make these angles tough to measure, and the points differ depending upon which angle I'm measuring. I find that when measuring the hip angle the line ought to pass from the greater trochanter through the shoulder, and through the [i]collarbone[/i] which, while in the aero position, will be in front of the shoulder. But when you're figuring your shoulder angle, the line representing the upper arm ought to pass through the centerline of the arm midway from front to back. The intersection of these two lines represents the apex of the shoulder angle being measured.)

It seems to me that looking at the clavicle/hip positions would be useful from an aerodynamic perspective but not from a power production perspective (especially in someone with a flexible back). I think one needs to look at both although I am not sure how one would do so as one cannot "know" from simply measuring someone how much of a quantitative effect a position has on either. Or am I missing something Dan or Tom.

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Frank,
An original Ironman and the Inventor of PowerCranks

Cobb's argument for pad positioning having an effect on power output had to do with the power gained from an "active" upper body - pushing and pulling on the aerobars (like Lance rides.) His research seems to indicate that by moving the forearm pads back, at a certain point you reduce the body's leverage on the aerobars, and thus reduce overall wattage.

As Dan pointed out to me last week, Greg Lemond's first comment on his use of the then-new aerobars was not that they increased his aero-ness, but that they gave him an additional point of leverage on the bike, which increased his power output. Interesting stuff.

MH

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

I agree with the concept of using aerobars to apply leverage, and also believe that this aspect of their use is very overlooked - it may even be their raison d'etre. By tensing the arms, the rider can lever their legs off the upper body. This is not dissimilar to riding out of the saddle.* As evidence for this, in the pre-aerobar era, top riders could both obtain and maintain aerodynamic positions on road or pursuit bars (I emphasise top riders here because doing this can be very uncomfortable), yet the introduction of aeorbars rapidly led to faster times, suggesting a positive biomechanical effect. (From having watched a documentary about one of Boardman's hour record attempts, I have a feeling that the UCI-outlawed superman position took this one step further.)

(*One of the posts gives an article that shows how standing on the pedals did not improve power output significantly. From what I could tell that research was done using a bicycle fixed to an ergometer. Assuming so, the participating cyclists would have been unable to rock the bike in the normal way for out-of-the-saddle cycling, and so could not have applied the leverage that this method should enable.)

What does this mean in practice? Apart from the pad placement mentioned above, the wrists should be kept low relative to the elbow. This opens up the elbow, aiding the application of force. (Note this is how most of the road pros set up their TT bars - eg look at Botero, someone who's fairly quick in a timetrial.) Achieving this set-up may affect bar choice. For instance, at the start of last season, I changed from Cinelli Angels to Vision-Techs. These prevented me from getting my hands low enough relative to my elbows, limiting the application of leverage. It took me some time to adapt, and I was never really happy. In addition, more force will be applied to the bars and they must be strong enough to withstand this, and bolts must be tightened appropriately. The Vision-Techs were at least rock-solid. In comparison, over the last couple of years, a number of pros in the three week tours have suffered loose or broken aerobars (again consistent with use of the bars for leverage). When using aerobars for leverage one tends to pull oneself forward, meaning regular sliding back on the saddle can be necessary.

duncan