TT hip angle versus watts for best aerodynamic?

Training
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Hello TT experts,
After lots of TT work on the kickr in winter and starting squats and deadlifts as well, I feel like I can close my hip angle again.
I opened it most possible in the UCI limits last years on my TT.
In last weeks my seatpost got lose and sunk down about 2 cm. And I did not feel it… :slight_smile:
I could do threshold without a problem. The watts were there…
My question: For best aerodynamic should be the hip as small as possible, without losing watts?

Hope I could explain it…
Greeting from Bavaria
Chris

2
  • That’s pretty much impossible to answer with any certainty.

You are implying that:

  • A more closed hip angle comes from more rotation at the hip and/or upper body (assuming the saddle height and fore-aft remains unchanged), and lower upper body as a result of that rotations (again, assuming appropriate changes to aerobar setup that allows for all changes mentioned before) which is is more aerodynamic.

The problem is that lower is not always more aerodynamic. In a pure frontal area sense it can be, but there is more to aerodynamics than frontal area. The side profile matters as well. It’s been mentioned by some people connected to pros that some people are actually more aerodynamic with a somewhat higher position than what they may be capable of sustaining for time and power requirements.

  • I would have to do some CAD modeling work to know for sure, but this example has some give AND take. Lowering the saddle will shorten your pedal stroke and leave your thigh bone higher, which could act to close your effective hip angle.

  • BUT, with the lower saddle (and same height aero bars), you may also open the hip angle since your back is presumably a bit more upright.

  • That’s what I mean by give and take. As with most fitting changes, even moving a single component in a single direction usually has multiple consequences to the body on the bike. It’s sure possible there is a mix of impacts that saddle drop delta caused, so I’d be cautious about drawing a firm conclusion without looking at ALL the aspects that got effected.

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Sadly aerodynamics aint that straight forward. You can try to find a “good” position using a mirror / filming yourself while on the indoor trainer, but in the end you will have to test it. As someone also from Bavaria I can recommend the guys from Aerofitting. They do all their testing on the Velodrome in Augsburg.