aerodynamics of an inch

[acoggan]

In this particular case, the one thing that is clear is that the effect of the proposed modification will be below the experimental noise of the methods you suggested. Not to be misunderstood, those methods are perfectly fine, in principle, but they are not sensitive enough to decide this question.

While I think you raise a valid point, I don't believe that you can automatically conclude that a 1" change in aerobar height would be undetectable in a field test. (Note that I'm assuming we're talking about a change in the rider's position, and not the impact of the extra 1" of round spacers themselves.) For example, starting from an already low position I found that lowering my elbow pads 3 cm made a small, but consistent, difference:

http://home.earthlink.net/~acoggan/whichisfasterthecervelop2torthejavelinarcole/

In this case, you'd have to do a lot of trials to establish statistical significance, but that wouldn't necessarily be true for somebody else starting from a higher position.

 

[Dietmar]

While I think you raise a valid point, I don't believe that you can automatically conclude that a 1" change in aerobar height would be undetectable in a field test. (Note that I'm assuming we're talking about a change in the rider's position, and not the impact of the extra 1" of round spacers themselves.)

Oh yes, I agree with this. When I wrote the quote you gave in your post, I was assuming, incorrectly as it turned out, that the rider's position would not change.

 

[frenchyge]

I found that lowering my elbow pads 3 cm made a small, but consistent, difference:

http://home.earthlink.net/~acoggan/whichisfasterthecervelop2torthejavelinarcole/

Cool, but would it be possible to see Figure 1 and Table 1? Sorry if I missed a link somewhere.

 

[Old Junker]

Alright, my fault, but I was confused by your reference to other things being equal.

no problem dietmar but i am finding some links /info finally what do you make of this one


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12355191&dopt=Abstract

 

[frenchyge]

no problem dietmar but i am finding some links /info finally what do you make of this one

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12355191&dopt=Abstract

That must have been the study that Wilmar commissioned.

 

[Old Junker]

That must have been the study that Wilmar commissioned.

how about this one

http://www.montana.edu/etd/available/unrestricted/Klippel_1204.pdf

 

[frenchyge]

how about this one

http://www.montana.edu/etd/available/unrestricted/Klippel_1204.pdf

106 pages? I'll wait for the cliff notes.

How about: http://analyticcycling.com/RiderAeroStudy.html ?

 

[Dietmar]

how about this one

http://www.montana.edu/etd/available/unrestricted/Klippel_1204.pdf

The first of the links you gave is not really relevant for you, the one in the quote above is mrginally relevant, but it talks about how your physiological efficiency is affected by (an aspect) of your position on the bike. May or may not be worth reading anyway, but my guess is that you will get little out of that one.

 

[Dietmar]

106 pages? I'll wait for the cliff notes.

How about: http://analyticcycling.com/RiderAeroStudy.html ?

That's a keeper, definitely! Quite useful, as far as it goes.

 

[wilmar13]

That must have been the study that Wilmar commissioned.

Well those Indian studies are not any good (damn Indian engineers, always great at theory terrible at application ).

Just for experimenting I raised my bars 30mm on my TT bike and moved my seat back 10mm. With this position I was less aero by judging from my (highly scientific) store front glass reflection. I did a TT on Wednesday in this position and had my best result so far this year (it is a series). The assumed aero drag increase, was more than offset by increased power. I did a 21:15 for the 10mile TT with previous best of 21:50 in the old aero position. It is also important to note that conditions were worse than any other time with a stout headwind on the uphill section of the track (it is around a paved 1.5mile oval racetrack)

Unfortunately I do not have power for the 21:50 time, but I did have a new high for 20 min power with a 405 watt NP for the TT (usually my max 20 minute power is 360-380 watts). I have also gained about 10 pounds putting me up near 200, so I can't say that all the extra power is due to the higher position (or more fat stores ), but I did feel much more comfortable during the TT.

At least in my case Power > Aero... so as others have already stated, the lower position IF more aero, may still be slower if you lose any power. Probably highly dependant on the individual.

 

[acoggan]

At least in my case Power > Aero

Given all the variables that you have changed at once, the fact that you don't have power for the 21:50 performance, etc., do you really think you can draw this conclusion? I don't (obviously).

 

[wilmar13]

Given all the variables that you have changed at once, the fact that you don't have power for the 21:50 performance, etc., do you really think you can draw this conclusion? I don't (obviously).

I will acknowledge that:
1) I don't know that the higher position is less aero
2) I don't know how much of my power increase is due to increased muscle mass, fitness/recovery level, etc. rather than position (but I was much more comfortable)
*forget about the lack of power data for the previous best time... in the higher position I was able to get a 20min power output that trumps what I have done all year in training and racing on that bike, in that lower position.

since I don't know that the higher position is less aero (although I am less "flat") you are correct... let me restate what I said:

higher position may = more power and who knows what the aerodynamic ramifications are

 

[wilmar13]

higher position may = more power and who knows what the aerodynamic ramifications are

Basically I was basing the Power > Aero on the perceived notion that lower = more aero even if not accurate, this thread seemed to make the assumption that it was i.e. how much faster/aero will I be by lowering the bar X amount when the inverse could be true (and was in my exhaustive errr exhausting N=1 study)

 

[frenchyge]

Basically I was basing the Power > Aero on the perceived notion that lower = more aero even if not accurate, this thread seemed to make the assumption that it was i.e. how much faster/aero will I be by lowering the bar X amount when the inverse could be true (and was in my exhaustive errr exhausting N=1 study)

Wow, a ~10% jump in power is pretty significant at those levels! I'd put some more thought/experimentation into what allowed that difference, and try to duplicate it, if possible. If it's due to raising your bars, then that'd be a great find for such a informal experiment.

For example, starting from an already low position I found that lowering my elbow pads 3 cm made a small, but consistent, difference:

http://home.earthlink.net/~acoggan/whichisfasterthecervelop2torthejavelinarcole/

Andy, any chance of seeing the referenced figure/table/chart in this experiment? I didn't see a link anywhere on that page.

 

[acoggan]

Andy, any chance of seeing the referenced figure/table/chart in this experiment? I didn't see a link anywhere on that page.

Sorry, I had to resurrect those pages after Kraig Willett yanked them from www.biketechreview.com...I'll see what I can do.

 

[wilmar13]

Wow, a ~10% jump in power is pretty significant at those levels! I'd put some more thought/experimentation into what allowed that difference, and try to duplicate it, if possible. If it's due to raising your bars, then that'd be a great find for such a informal experiment.

Let's just say that I was relieved to not be named in Opercion Puerto

Nah, like Andy pointed out, too many things are different to make a meaningful conclusion... the stars were aligned, I had a good day or whatever. The biggest factor could be weight gain, I have gained about 10 lbs in the last 2 months or so and perhaps I was actually weakened by trying to get the sunken chest and pipe cleaner arms level... but I am not willing to put the bars back down to the headset again just to see.