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Aero bar power drop...

post #1 of 71
Thread Starter 
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
post #2 of 71

Re: Aero bar power drop...

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?
post #3 of 71

Re: Aero bar power drop...

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?
post #4 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by 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?

Mr. Nail, meet Mr. Head.


At the 2005 US Masters Nat's Gil Hatton won the 45-49 kilo on regular drop bars.
post #5 of 71

Re: Aero bar power drop...

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.
post #6 of 71

Re: Aero bar power drop...

Can someone explain what "NP" stands for ?
post #7 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by 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.
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?
post #8 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by WarrenG

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?
post #9 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by 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
How often are you training in aero bars? I suspect power will come back up if you ride in that position more.
post #10 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by 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?
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.
post #11 of 71

Re: Aero bar power drop...

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.

Quote:
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/abst...856145!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/.../PevelerV2.doc
post #12 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by JTE83
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/...ingChapter.pdf

(Note: the latter is the chapter on power-based training that I wrote for the USA Cycling level II coaching manual.)
post #13 of 71

Re: Aero bar power drop...

Quote:
Originally Posted by whoawhoa
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?
post #14 of 71

Re: Aero bar power drop...

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.
post #15 of 71
Thread Starter 

Re: Aero bar power drop...

Quote:
Originally Posted by 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?
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.
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