Is Time Trial position different than Tri position?

Triathlon Forum
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The post on Max Testa’s fitting pointed out that road riders such as Lance, Indurain et al. ride with a more shallow seat angle than FIST position. Is this a better position for riding, if you don’t have to run off of the bike or should FIST put you in a more aero and better position regardless of time trialing or cycling as part of a multi-sport event?

I thought I understood from reading Dan’s articles that in moving from a road position to an aero position you want to maintain the same angles at the hip but rotate the body forward, requiring the steeper seat angle.
This would imply that TT’ers and triathletes should both use FIST fitting.
But this is not the case in the real world.
Can Dan and others comment on whether or not FIST applies for both Time Trialing and multi-sport and why cyclists ride Time Trials with more shallow seat angles?

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“TT’ers and triathletes should both use FIST fitting.”

A number of factors to consider with TT’ers

  1. the rules stipulate that the saddle tip must be 5 cm behind the BB. This means a shallow angle.

  2. Even if the rules were changed it’s likely that most wouldn’t go steep because they ride many hours shallow in road racing/training and the conventional TT position mimics this and this is what their bodies are used to.

  3. They don’t have to run afterwards

  4. The world’s fastest TT’ers are faster than the world’s fastest triathletes so it’s unlikey that they are going to change just because some triathletes tell them so.

  5. Nobody has actually proven (there was one limited study on a stationary bike) what the optimum seat angle really is. It probably varies from individual to individual.

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There is a definate difference in the set up for a TT v the bike leg of tri (even ignoring UCI regulations for TT bikes). Let’s start by looking at the nature of what the two disciplines entail:

TT: Maximum sustainable effort for normally a relatively short duration (1 hour or less). Fractions of a second can be significant. No running afterward. Speed are higher.

Bike Leg of a Tri: A metered out effort leaving enough in the tank to complete a running event immediately following it. Often just the bike leg of a tri is longer than a TT, much less looking at the combined duration of the whole event, thus effort leves need to be lower. Speeds are thus lower.

OK, keeping that in mind it is important to think about the strategy for maximum performance. In a TT the fastest way to ride a course is not actually at a steady pace. For example, going a bit over a sustainable effort on the climbs and slightly backing off the effort on the downhill sections leads to a faster time that keeping a perfectly steady output (due to the increase in velocity per unit engergy being higher on a climb where drag is less of a component than on a downhill where drag is effectively the only component, which goes up at a cubic rate, meaning you use more energy per unit increase in velocity). This means considering a position which can allow for higher torque loads needed for accelerations is important. In a tri, such efforts will come back to haunt you on the run, often leading to a slower combined run/bike.

Next, looking at not having to run off the bike means you don’t have to worry about the position’s effect on running for TT set up. Because of this you can close the acute angle at the hip down more than for tri. Because of this an athlete can stay further back on the bike, which can lead to a more aero position assuming the athlete has good ability to go deep into flexion at the hip. Given the higher speeds in time trials the added aero advantage is significant.

I’ve been lucky enough to set up the positions of some really fast time trialists and triathletes alike, and I can tell you that the positions some of those TT riders end up in are not ones you would ever want to consider trying to hold for any length of time, nor would you want to try to run from them.

As a side note, one area Slowman and I differ is in hip measurements when doing fittings - he looks at the obtuse hip angle and I concern myself with the acute angle, particularly for TT fitting when using up basically all of the athletes range of motion is important to reducing drag. We both see the merits of the other measurement - just different approaches.

This is the short, to too well explained answer to your question, but I hope it helps shed some light on the subject.

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“Slowman and I differ is in hip measurements when doing fittings - he looks at the obtuse hip angle and I concern myself with the acute angle”

I’ve wondered about this myself. The 90 degree obtuse angle is a standard for everyone but there could be quite a bit of difference in the acute angle from rider to rider depending on individual hip flexibility. Each rider would have to be measured individually.

I think setting up a TT position is even more of a challenge than setting up a tri position for the reasons you’ve already described.

Since I’m a chiropractor with a fairly sound understanding of biomechanics I’ve always though some of my basic examination could be utililized into bike fitting. I have a number of metering devices in the office that measures cervical or lumbar spine flexibility for example. Then test the flexibility of the hamstrings, quads, hips, etc. The problem as I’ve seen it is that in a standard fitting you could have any two riders with identical static measurements but their dynamic measurements of flexibility could be quite different.

Just curious how you incorporate an acute angle measurement into a bike fitting? I have not actually used this as a crtieria but have some ideas why it could be important, so am very curious to hear your reasoning.

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