Power out put difference between Road bike and tri bike

I Had fit in the last year and half around 60 people most of them triathletes, and this is the first time that a customer came with the question :
He can power around 200 Watts, constant in his road bike ( which I fit him ), recently he bought a Cervelo P3 ( also fit him) and he can’t generate the same power.
He will be 10 to 15 % less powerful, and mostly when he is in the aero position.
His knee angle 149 , seat angle is 79,8 shoulder angle 90 .Every thing looks so perfect.
Is any thing that I missing here?
Thank you very much in advance for a good feedback if you know the possible steps to follow.
Marcelo

Completely normal. Mainly it’s related to the hip angle being more acute on the TT bike than the road bike.

It may be worth the decreased power output if they are significantly more aero. If it’s some lousy FIST fit with all 90 degree angles then it’s not worth the reduction in power.

How much time does the athlete spend training on each bike? More time on the TT/Tri bike will narrow the difference.

It is certainly not completely normal to lose 10-15% of your power when riding aerobars. Maybe 10 watts/ 2-3%. Maybe.

What you are missing is hip angle. When you measure it, it should not be any different then a road bike hip angle when the rider is forward and low, “breakaway style”.

I will try to answer to three of you ,
Is true that the hip angle change, but remember that following the F.I.S.T I can’t really test his closed Hip angle.
The other thing this guy is been working very hard during a year on his road bike now every thing change , he has to work more with hamstrings and gluts.
May be is the answer, or combination of both.
I wish I had the silver bullet for every difficult case .
Thank you, if you think about any thing else I will appreciate.
Marcelo

so torbjorn and rappstar have lousy fits?

If it’s some lousy FIST fit with all 90 degree angles then it’s not worth the reduction in power.

I Had fit in the last year and half around 60 people most of them triathletes, and this is the first time that a customer came with the question :
He can power around 200 Watts, constant in his road bike ( which I fit him ), recently he bought a Cervelo P3 ( also fit him) and he can’t generate the same power.
He will be 10 to 15 % less powerful, and mostly when he is in the aero position.
His knee angle 149 , seat angle is 79,8 shoulder angle 90 .Every thing looks so perfect.
Is any thing that I missing here?
Thank you very much in advance for a good feedback if you know the possible steps to follow.
Marcelo

what is his OPEN hip angle? That serves as a reasonably good proxy for closed hip angle, which is why FIST uses it.

Completely normal. Mainly it’s related to the hip angle being more acute on the TT bike than the road bike.

It may be worth the decreased power output if they are significantly more aero. If it’s some lousy FIST fit with all 90 degree angles then it’s not worth the reduction in power.

Completely “normal” doesn’t actually means it something you should tolerate. It is now “normal” for a random person off the street in America to be obese. Likewise it’s “normal” than a person riding a bike with aerobars has a shitty fit.

There are numerous ways to get around too closed a hip angle on a TT bike. If it’s a tribike, you can move them steeper. If it’s a UCI-restricted TT position, moving to shorter cranks is another very good option. For UCI riders, you can also look at something like what Joe Santos of Davis Wheelworks is doing where he moves them quite slack and then the bars way up. He’s had some consistent success with that.

As far as the lousiness of FIST, let’s look at the success - in pro cycling - of FIST (here’s a hint - Dan taught it to Gerard Vroomen, who brought it to Bjarne Riis, who uses it across the board). Recall, on this very forum, Dan saying, “Alberto is too stretched out.” 'Berto joins Saxo Bank. Bjrane looks at his position. Alberto says, “I was too stretched out, and it was costing me power.” Funny that…

What’s your counter-example again?

Completely normal. Mainly it’s related to the hip angle being more acute on the TT bike than the road bike.

It may be worth the decreased power output if they are significantly more aero. If it’s some lousy FIST fit with all 90 degree angles then it’s not worth the reduction in power.

Completely “normal” doesn’t actually means it something you should tolerate. It is now “normal” for a random person off the street in America to be obese. Likewise it’s “normal” than a person riding a bike with aerobars has a shitty fit.

There are numerous ways to get around too closed a hip angle on a TT bike. If it’s a tribike, you can move them steeper. If it’s a UCI-restricted TT position, moving to shorter cranks is another very good option. For UCI riders, you can also look at something like what Joe Santos of Davis Wheelworks is doing where he moves them quite slack and then the bars way up. He’s had some consistent success with that.

As far as the lousiness of FIST, let’s look at the success - in pro cycling - of FIST (here’s a hint - Dan taught it to Gerard Vroomen, who brought it to Bjarne Riis, who uses it across the board). Recall, on this very forum, Dan saying, “Alberto is too stretched out.” 'Berto joins Saxo Bank. Bjrane looks at his position. Alberto says, “I was too stretched out, and it was costing me power.” Funny that…

What’s your counter-example again?

Jordan, it’s funny you mention Contador. I was just watching the TT from this years Vuelta a Castilla y Leon last night on my computer. While his position does look better than before, I think he still looks stretched out. He still does “the Contador” where he slides forward on the saddle gradually over 4-5 seconds and then shifts back. Is this just the nature of his power output vs weight (or lack thereof)? Or is there still something fit related going on with him? I don’t see other pro riders doing this, so I can’t imagine it’s due to the UCI setback requirements.

My watts on a flat road are the same in either position.

Isn’t being stretched out more aero? Maybe he was faster that way. We will never know.

I was wondering the same thing. I’m on a road bike with a TT setup. Anyway, I did all my training this winter in the road position and recently got aerobars. I haven’t officially tested in aero position but I plan to next week. To do a test set before testing aero FTP, I arbitrarily decreased my road position FTP by 10%. Performed 2x20 at 95% of that number in the aero position. I had a really tough time and had to come out of aero during the second set. Legs were really killing me.

Was just trying to make sense of what’s going on. Not sure if it’s the bad aero position or just not enough time at high power output in aero. I’m assuming a tri bike would allow me to get into a better position where I can maintain power but I’m just guessing here.

Isn’t being stretched out more aero? Maybe he was faster that way. We will never know.

It CAN be. But it’s also VERY hard to sustain. The only way it seems to be sustainable is if you ride quite slack (a la Lance), which is what Joe Santos does. Otherwise, your spinal erectors have to do too much work. The other way in which it can be sustainable is for quite short races (20km or less) and if you are REALLY light in the upper body. There are quite a few female TTers (Kristin Armstrong being the most notable) who are “too stretched out.” But Kristin is TINY (most cyclists are small, and females tend to smaller than men, and… Well, most female cyclists are pretty dang little), so her upper body simply weighs less. And she races generally about 1/2 as far as the men do.

You also need to be quite short to be able to be too stretched out and still not violate the UCI 75cm cockpit rule. Pretty much, you’d need to be someone with a saddle height of <75cm, which generally means a pretty little rider. But I also think that it’s only really sustainable for super short periods of time unless you ride quite slack, which most people do NOT want to do. Though some folks have trained themself to do so successfully.

Here’s the problem with your statement as it reads. More aero DOES NOT necessarily mean faster. It only means faster if you don’t lose power. Or, more specifically, if you do a good job balancing power loss with drag reduction. Now, the BIG mistake most people make is doing this math for flat ground. That math doesn’t hold though if you start to go uphill at 1% grade. So it’s very hard to figure out how much power you “can” lose without it being problematic, since it’s totally dependent on course topography.

My own advice/opinion is that balancing that equation is basically impossible. Therefore find the position in which you generate the most power. Then optimize aerodynamics. You should also experiment with things like shorter cranks, etc. to attempt to eliminate the most common things which kill power in an aero position - too closed an acute hip angle.

Is it possible the road bike position has the KneeOverSpindle, and the P3 with the steep saddle angle moves the knee farther forward resulting in a bio-mechanical loss of torque?

In away your problem is different, because you are changing the angles.
You are in a road bike position and you put aero bars and what look’s liked that you are pedaling quite a bit with your quads instead using your gluts and hamstrings .
thank’s
Marcelo

Maybe lousy was too strong a word.
http://groups.google.com/group/wattage/msg/ad8dc4a0abf02514?hl=en

I think he had a cockpit problem AND a saddle problem. Now I think he just has a saddle problem.

This is what happen , when I position the laser over knee over the spindle he was forward , I moved the saddle as much as possible, but was not enough .
If I change the position in the next hole in the back he was completely out .
I think you are with right answer, even do F.I.S.T. doesn’t measure this but Paul Swift from bikefit ,is his ABC.
Thank you all of you for this outstanding answers.
Marcelo from Calgary Canada.

I think he had a cockpit problem AND a saddle problem. Now I think he just has a saddle problem.

By that, do you mean you think his setback is too much? Or do you mean he has a saddle choice problem? Looked to me that he changed from his griptaped carbon saddle to a prologo, but I couldn’t tell which one.

I Had fit in the last year and half around 60 people most of them triathletes, and this is the first time that a customer came with the question :
He can power around 200 Watts, constant in his road bike ( which I fit him ), recently he bought a Cervelo P3 ( also fit him) and he can’t generate the same power.
He will be 10 to 15 % less powerful, and mostly when he is in the aero position.
His knee angle 149 , seat angle is 79,8 shoulder angle 90 .Every thing looks so perfect.
Is any thing that I missing here?
Thank you very much in advance for a good feedback if you know the possible steps to follow.
Marcelo
what is his OPEN hip angle? That serves as a reasonably good proxy for closed hip angle, which is why FIST uses it.

I’m a little confused by what you are trying to convey. Are you suggesting his open hip angle should be the same on the tri bike as the road bike? Or that FIST has guidelines for hip angles? Not trying to challenge what you are saying, just trying to understand what you are getting at. Thanks