Aero bar power drop...

[peterwright]

Guys

I have now done 5 16km TTs in 6 weeks at a local event. The first one I did gave me an NP of 288 (no aero bars) the next 3 gave an NP of 271-274 with aero bars. Tonight I rode in the drops again and saw NP of 286.

around 5% more power due to no aero bars ?

Is this what you have experienced ?

Cheers

Peter

 

[gclark8]

Your aero bars may not be correctly set up, your elbows may be too close to each other and the body position too far back on the bike. What is the seatpost angle and is the seat offset to the front or rear? What bike is it?

 

[SolarEnergy]

Position on the bike is a compromise. The more aero you get, the less power you can apply on the pedals, vice-versa.

Now, the real question, were the "aero" TT faster than the "non-aero" ones?

 

[WarrenG]

Position on the bike is a compromise. The more aero you get, the less power you can apply on the pedals, vice-versa.

Now, the real question, were the "aero" TT faster than the "non-aero" ones?

Mr. Nail, meet Mr. Head.


At the 2005 US Masters Nat's Gil Hatton won the 45-49 kilo on regular drop bars.

 

[SolarEnergy]

It is a clear example. I admit.

Although, on longer TT, I think it is worthwhile to sacrifice a bit of power for better aerodynamic profile.

 

[JTE83]

Can someone explain what "NP" stands for ?

 

[WarrenG]

It is a clear example. I admit.

Although, on longer TT, I think it is worthwhile to sacrifice a bit of power for better aerodynamic profile.

Yes, yes. Your advice is exactly right. Gil's kilo was an extreme example to show that aero is not the first priority. As you suggested, speed or time over the distance is first priority. Maybe for a triathlete/duathlete there are other considerations when weighing aero vs power as they relate to time on the bike? Especially in events that allow drafting?

 

[whoawhoa]

At the 2005 US Masters Nat's Gil Hatton won the 45-49 kilo on regular drop bars.

Because of, or in spite of? I'm betting the latter. BTW, when was the last time a rider from a major track racing country won the Elite Pursuit on drop bars?

 

[whoawhoa]

Guys

I have now done 5 16km TTs in 6 weeks at a local event. The first one I did gave me an NP of 288 (no aero bars) the next 3 gave an NP of 271-274 with aero bars. Tonight I rode in the drops again and saw NP of 286.

around 5% more power due to no aero bars ?

Is this what you have experienced ?

Cheers

Peter

How often are you training in aero bars? I suspect power will come back up if you ride in that position more.

 

[Iron Man]

Your aero bars may not be correctly set up, your elbows may be too close to each other and the body position too far back on the bike. What is the seatpost angle and is the seat offset to the front or rear? What bike is it?

Clarkie is on the money I experienced the same thing when i started out with aero bars, Have you moved your seat forward? This often needs to be done to maintain a high cadence.



Also with the training you need to work on staying on your bars for as long as possiblethis trains you in keeping your head and back still so you get a nice smooth airflow over the top of your body, otherwise you generate turbulent air which slows you down.

 

[SolarEnergy]

Of course one must find a good riding position, when using aero bars.

Moreover, I have rarely seen a good position when installing aero bars on a classical road bike, without changing any parts, or at the very least, moving the saddle a bit forward (and higher very often).

How do you call the part on which the handle bar is fixed? A seam? A seant? Whatever, that part often need to be replaced too.

But more aero, means less power.

We concluded that riding a bicycle in an extreme aero-position increases the metabolic cost of cycling when wind resistance is not taken into account. However, when the mechanical power losses of 9 W (estimated by the [spacing dot above]VO2 increase) are compared with the expected aerodynamic power savings of approximately 100 W, it appears that aerodynamic advantages by far outweigh their metabolic cost

http://www.ms-se.com/pt/re/msse/abstract.00005768-199706000-00013.htm;jsessionid=DqbDITD1U84pSAVHX4o9OryfBlSsjOR6tgFOnNX1DIdLKDs7FS4Q!10514069!-949856145!9001!-1

That is one, there are probably others where power got measured with a power meter, instead of being estimated.

** Edit ** I found at least one that contredicts.

Here, anaerobic power got tested. Two groups. CT=Cyclists, AT=Triathletes. For some mysterious reasons, triathletes could maintain a higher avg power on a 30s duration, in aero position, compared to upright position.

But the peak power output was higher in upright position for the two groups.

http://www.asep.org/jeponline/issue/Doc/Oct2004/PevelerV2.doc

 

[acoggan]

Can someone explain what "NP" stands for ?

Normalized power. For a brief overview, see:

http://www.cyclingpeakssoftware.com/defined.html

For more details, including precisely how normalized power is calculated, see:

http://www.cyclingpeakssoftware.com/PowerTrainingChapter.pdf

(Note: the latter is the chapter on power-based training that I wrote for the USA Cycling level II coaching manual.)

 

[WarrenG]

Because of, or in spite of? I'm betting the latter. BTW, when was the last time a rider from a major track racing country won the Elite Pursuit on drop bars?

I suspect that if Gil spent a bunch of hours training and practicing with aero bars just like those elite riders he'd chose aero bars, but for someone like him, and many of us who won't spend lots of hours practicing and training in the aero position for a kilo his approach may be worth consideration.

BTW, doing a kilo at ~36-37mph peak speed is not that easy in the turns with aero bars unless you've some hours practicing at speed, or has your experience been different?

 

[SolarEnergy]

One thing I didn't mention.

For those who would be tempted to install aerobars on a road bike, without having your position analyzed.

Instead of the usual "just listen to your body" stuff, I would add, listen carefully to your nuts. Sitting on your toolbox for hours can be pretty damaging. I have seen it at some occasions. Be careful. And spend a lot of time playing with the adjustments.

 

[peterwright]

Position on the bike is a compromise. The more aero you get, the less power you can apply on the pedals, vice-versa.

Now, the real question, were the "aero" TT faster than the "non-aero" ones?

The 3 I have done with aero bars were around 15 seconds quicker at the lower NP. Another variable however is that the course is very very windy on the out leg and very fast on the return - this means that I definitely lose time on the return leg with no aero bars.

I am not that concerned about it as I simply bolt the bars on to my road bike and am not prepared to move the saddle etc as I do the event as a training session anyway.

I was just interested to note the diff in NP.

 

[SolarEnergy]

The 3 I have done with aero bars were around 15 seconds quicker at the lower NP. Another variable however is that the course is very very windy on the out leg and very fast on the return - this means that I definitely lose time on the return leg with no aero bars.

Could it be the opposite?

15sec isn't bad over 16k. I believe that by improving the biomechanical efficiency, you can gain an extra 15sec quite easily.

There are various types of aerobars. Some will put you in a steep, set forward position, bringing you almost over your front weel. They have very few potential for adjustability.

Others, you can easily adjust the "telescopic" extention. That way, you don't screw up the whole balance on the bike.

Have fun !

 

[frenchyge]

Instead of the usual "just listen to your body" stuff, I would add, listen carefully to your nuts. Sitting on your toolbox for hours can be pretty damaging. I have seen it at some occasions. Be careful. And spend a lot of time playing with the adjustments.

Those tri-guys sit on their nuts for hours at a time, too? That adds a whole new meaning to the term Iron Man!

Tilting the nose of the saddle down slightly will help when you push the saddle forward for power. I've also seen advice that suggested turning the saddle slightly to one side, to give the 'tools' a little more room on the other. That seems like it might feel a little weird, but has anyone tried it?

 

[shawndoggy]

I've also seen advice that suggested turning the saddle slightly to one side, to give the 'tools' a little more room on the other. That seems like it might feel a little weird, but has anyone tried it?

Yeah, I have my saddle turned ever so slightly down and to the right (a degree or two at the most). It makes a big difference for me. Note I also run an old school 80s Turbo saddle on the TT rig -- just can't get comfortable in the aero position with a new school flat saddle like the one on my roadie. The turbo has a big fat rounded nose that really supports the taint (too much information, I know).

Back to the OP -- I'm with the camp that says that if you practice and fine tune your position you'll get most (if not all) of that power back. It's almost like trying to make the same power between an roadie and a mtb. If you don't practice, in the new position you won't make the same power as the "old" position (where you obviously DO practice making power).

 

[SolarEnergy]

Back to the OP -- I'm with the camp that says that if you practice and fine tune your position you'll get most (if not all) of that power back.

With all due respect to your opinion (you seem to know your business), I disagree.

And because of this...

I am not that concerned about it as I simply bolt the bars on to my road bike and am not prepared to move the saddle etc as I do the event as a training session anyway.

...I even think the OP should simply unbolt his aerobars set, and do this "training" in a way that is more specific to his specialty, and that is, riding using the regular handle bars drops. After all, that event is probably between 21 and 25 minute long.

That way, he will only loose 15 or 20 seconds on the finish line, and in the same time, the higher power (NP), will make the ride more specific, at least biomechanically speaking. Not to mention about potiential for injuries.

 

[whoawhoa]

I suspect that if Gil spent a bunch of hours training and practicing with aero bars just like those elite riders he'd chose aero bars, but for someone like him, and many of us who won't spend lots of hours practicing and training in the aero position for a kilo his approach may be worth consideration.?

Excellent point, and something I didn't think about, but your conclusion still seems to be that aero bars will be faster, with some work.

BTW, doing a kilo at ~36-37mph peak speed is not that easy in the turns with aero bars unless you've some hours practicing at speed, or has your experience been different?

My "experience" on the track is nonexistent!