New study on the effects of seat tube angle (for those of you who care about this stuff)

Mar 19, 08 18:00

Post #1 of 42 (4187 views)

We completed this study a couple of years ago but finally got around to publishing it. The original idea for the study design was sparked by some of the discussions on this forum (thanks for your help) so I thought some of you might be interested. Nothing earth shattering and the study certainly has its limitations but it adds to the body of knowledge. BTW, don't critique the pictures too harshly, they were taken rather quickly and don't accurately represent the more precise positioning of the subjects.

The study is published here: http://www.asep.org/journals/JEPonline and is available full-text online. Just open the link to the current issue (Feb 2008) and go to the second page of the table of contents to download the article. The abstract is below for those who just want the cliff notes.

Effects of Seat-Tube Angle on the Metabolic Cost of the Cycle-Run Transition in Triathletes. JEPonline 2008; 11(1):45-52. The purpose of this study was to investigate the effects of two different (73� and 81�) seat-tube angles (STA) on cardiorespiratory measures during cycling and a subsequent treadmill run. Ten male triathletes completed a 40-minute �time-trial� at a pre-determined workload on a cycle ergometer at 73� and 81� STAs and immediately transitioned to running on a treadmill at a pre-determined pace. Oxygen consumption (VO2) and heart rate (HR) data were collected during the last 5-minutes of cycling and first 5-minutes of running. Consistent hip and knee angles were maintained between cycling conditions. There were no differences in VO2 for cycling or running between the 73� and 81� STA conditions. Heart rate was significantly lower during cycling at the 73� STA (p<0.05). There were no differences in running heart rates. These results suggest that if bicycle seat-tube angle is changed, but hip and knee angles remain consistent, there is no difference in the metabolic cost of cycling or a subsequent treadmill run.

Kurt

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 19, 08 19:10

Post #2 of 42 (4134 views)

Very eeeeeenteresting. The only constructive criticism that I have, which is addressed to a certain extent in the "limitations" section of the paper, is that the cyclists were only measured for the last 5 minutes of the bike portion of the test. Additionally, I hypothesize that an increased STA may have more effect on cycling and running performance if the cycling portion of the test is more extensive. Say, 90 minutes or two hours instead of just 40 minutes.

Otherwise, looks like an interesting and academically rigorous examination of triathlon STA!

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 19, 08 19:13

Post #3 of 42 (4124 views)

did the subjects mention a difference in perceived effort for the run?

Ride Scoozy Electric Bicycles
http://www.RideScoozy.com

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 19, 08 19:21

Post #4 of 42 (4109 views)

"Heart rate was significantly lower during cycling at the 73� STA "

Any explanation for this?

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [cerveloguy] [ In reply to ]

Mar 19, 08 19:36

Post #5 of 42 (4083 views)

"Any explanation for this?"

i would ask whether cadence was kept constant. basically, all things equal, if you want your HR lowered, lower your cadence. typically, shallower seat angles couple with lower cadences.

Dan Empfield
aka Slowman

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [Slowman] [ In reply to ]

Mar 19, 08 19:42

Post #6 of 42 (4073 views)

In Reply To:

"Any explanation for this?"

i would ask whether cadence was kept constant. basically, all things equal, if you want your HR lowered, lower your cadence. typically, shallower seat angles couple with lower cadences.

I was counting the seconds before you caught this one...

Come on now folks--he provided a link to the entire article. There's a hypothesis as to why HR was higher, and the cadence info is all in there.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 19, 08 19:43

Post #7 of 42 (4070 views)

I am just thinking out loud, but after the bike ride do you think it would be a better test if you let the subjects run at their own pace. Instead of testing their VO2 or heart rate, test their mile TT.

Ride Scoozy Electric Bicycles
http://www.RideScoozy.com

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [Slowman] [ In reply to ]

Mar 19, 08 19:46

Post #8 of 42 (4063 views)

In Reply To:

"Any explanation for this?"

i would ask whether cadence was kept constant. basically, all things equal, if you want your HR lowered, lower your cadence. typically, shallower seat angles couple with lower cadences.

Dan,

I believe that the article mentions that while cadence was not forced to be constant, the participants had approximately the same cadence at 73 degrees and at 81 degrees. 92.x (73) versus 91.x (81) I think. Though I admit that forced identical cadences would be nicer, this seems like a pretty good way to address this issue.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 19, 08 19:48

Post #9 of 42 (4061 views)

1) I didn't read the article, just the cliff notes

2) One would expect the power to be the same if the hip angle remains the same

3) One would expect higher HR when the upper torso is in the aero position, since being in that position is more restrive for the torso (neck extended up, and arm tucked in to at least some extent

4) Even tho the power output was the same for both angles, the SPEED in the aero position would be higher due to lower drag (that's the whole point of aerobars in the first place!).

5) Therefore the aerobar rider (81deg) would get to T2 sooner than the roadie, and run the same speed off the bike

6) A better test would have been to test both riders in the same aero position, but with different hip angles. This would change the power output (one would expect lower power with 73deg, due to being bunched up) and likely the oxygen uptake (and HR for the same power) and the aero effects would be largely nullified. (Important since this is a static (no wind resistance) test)

Just my 2 cents

TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [tridork] [ In reply to ]

Mar 19, 08 20:12

Post #10 of 42 (4037 views)

In Reply To:

1) I didn't read the article, just the cliff notes

2) One would expect the power to be the same if the hip angle remains the same

3) One would expect higher HR when the upper torso is in the aero position, since being in that position is more restrive for the torso (neck extended up, and arm tucked in to at least some extent

4) Even tho the power output was the same for both angles, the SPEED in the aero position would be higher due to lower drag (that's the whole point of aerobars in the first place!).

5) Therefore the aerobar rider (81deg) would get to T2 sooner than the roadie, and run the same speed off the bike

6) A better test would have been to test both riders in the same aero position, but with different hip angles. This would change the power output (one would expect lower power with 73deg, due to being bunched up) and likely the oxygen uptake (and HR for the same power) and the aero effects would be largely nullified. (Important since this is a static (no wind resistance) test)

Just my 2 cents

I haven't seen any evidence of number 4, and I question (as have others) just how far forward one really has to go to 'preserve the hip angle' when going from a 'slack' ST angle to a 'steep' ST angle.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [roady] [ In reply to ]

Mar 19, 08 21:02

Post #11 of 42 (3996 views)

In Reply To:

In Reply To:

1) I didn't read the article, just the cliff notes

2) One would expect the power to be the same if the hip angle remains the same

3) One would expect higher HR when the upper torso is in the aero position, since being in that position is more restrive for the torso (neck extended up, and arm tucked in to at least some extent

4) Even tho the power output was the same for both angles, the SPEED in the aero position would be higher due to lower drag (that's the whole point of aerobars in the first place!).

5) Therefore the aerobar rider (81deg) would get to T2 sooner than the roadie, and run the same speed off the bike

6) A better test would have been to test both riders in the same aero position, but with different hip angles. This would change the power output (one would expect lower power with 73deg, due to being bunched up) and likely the oxygen uptake (and HR for the same power) and the aero effects would be largely nullified. (Important since this is a static (no wind resistance) test)

Just my 2 cents

I haven't seen any evidence of number 4, and I question (as have others) just how far forward one really has to go to 'preserve the hip angle' when going from a 'slack' ST angle to a 'steep' ST angle.

TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [tridork] [ In reply to ]

Mar 19, 08 23:47

Post #12 of 42 (3924 views)

i had similar thoughts re; 4/5/6.

my understanding is that a steep ST angle allows the rider to get aero while retaining an open hip angle.

by doing the test on an ergometer nullifies the aero effect making the test somewhat inaccurate.

I reject your reality and substitute my own!
Adam Savage

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [slidecontrol] [ In reply to ]

Mar 20, 08 9:56

Post #13 of 42 (3737 views)

Quote:

by doing the test on an ergometer nullifies the aero effect making the test somewhat inaccurate.

Quote:

I agree that it nullifies any potential aero effect, but I don't think it makes the test inaccurate. instead, I think it may help to isolate the possible list of benefits from riding steep. For example, if this test shows that, but for STA, all other things are equal, then you could presume that the ONLY difference is the aerodynamic benefit, if any, from position. Those who ride high in front could rethink whether they should be on a road bike or tri bike, if not riding aerodynamically (esp. if they find a road bike more comfortable over any given distance). And I suppose you could conclude that the various theories relating to different muscle recruitment (and how they relate to efficiency) are shown here to be disproven, or questioned.

But I don't know that the ergo makes it inaccurate. I'm really suprised this hasn't generated more discussion from people a lot smarter than me - but this place is starting to evolve (devolve?) to discussions surrounding contemplating one dude's navel in the pool area

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 20, 08 11:27

Post #14 of 42 (3663 views)

I had the same questions about a stationary bike vs real world aerodynamics, but of course they cannot be answered with this study, so it is a moot point here. It does however make all the difference in the world. Only other problem is that who here only rides 40 minutes, then runs 5 or 10 minutes. Just like with wetsuits, the major differences are in the back half of the race, not the first half where you are fresh, and there is not enough time for differences to show up. I bet if you did this test with a one speed cruiser bike, the run results would also be the same, or maybe a unicycle..

The proper way is to do it at race pace for a period of time that gives a chance for any difference to surface, if in fact there is one. You also have to take into account the fitness of the athletes, and what position they have been training in prior to the test. That is the problem with most of these things, there are so many variables, that you really have to do your homework in advance to get meaningfull results....

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [tridork] [ In reply to ]

Mar 20, 08 11:46

Post #15 of 42 (3635 views)

"One would expect higher HR when the upper torso is in the aero position, since being in that position is more restrive for the torso (neck extended up, and arm tucked in to at least some extent "

That is a more logical explanation to me than Slowman's cadence theory since I've always rode consistantly at the same 95-105 cadence on both my road and tri bikes. My HR was always a bit higher on the tri bike on the road or trainer. I always contributed it to two factors 1) holding my neck in more extension 2) crotch discomfort on the tri bike.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 20, 08 11:55

Post #16 of 42 (3622 views)

Very interesting, will keep in mind next time I am on a stationary bike.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [monty] [ In reply to ]

Mar 20, 08 12:50

Post #17 of 42 (3573 views)

"...the major differences are in the back half of the race, not the first half where you are fresh, and there is not enough time for differences to show up."

The evidence disagrees with your assertion. Their paper cites two other papers that show that the differences are most evident in the first few minutes of the run, not the second half. Here's a link to one of them.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [cerveloguy] [ In reply to ]

Mar 20, 08 12:58

Post #18 of 42 (3567 views)

i was thinking about the HR differences between the positions in the experiment.

we know the hip angle was retained between the the two ST angles tested.

it has been 'assumed' the power output was similar although no mention was made in the OP

my next thought was how was the riders front end supported during the test?

we now know ( thanks to the work of Dan and others) the when riding steep the upper body needs to be supported properly (skeletally) on the aerobars rather than muscularly (sp?) where as riding slack moves more of the riders weight over the saddle.

if the front end was not dialed to suit the rider in the aero position, would there not be a measurable increase in HR as the upper body would be working considerably harder to maintain position?

I reject your reality and substitute my own!
Adam Savage

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [slidecontrol] [ In reply to ]

Mar 20, 08 13:02

Post #19 of 42 (3554 views)

Sheesh, read the article, folks. You can see for yourself whether the rider is supported muscularly or skeletally by looking at the photo of one of the subjects in it.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [rubberband] [ In reply to ]

Mar 20, 08 13:05

Post #20 of 42 (3548 views)

It's quite possible that differences occur at the beginning of the run, but what I'm saying is that you have to do the entire bike first, and then the entire run to ascertain that there is in fact a difference. I'm not sure what studies were cited, but in order to know if you are improving the first part of a run, don't you have to do the second part too?? In other words, if you only test 5 or 10 minutes, even if it is faster, don't you have to test the last 30 or 40 minutes to see if you gave it back for some reason???? Like I said, it is a lot more complicated that it appears at first glance, and I just don't think you get anything meaningful from a 40 minute ride(at some unknown pace), going into a 5 to 10 minute run(also at some unknown pace)....

Last edited by: monty: Mar 20, 08 13:09

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [monty] [ In reply to ]

Mar 20, 08 13:09

Post #21 of 42 (3535 views)

The cite prior articles that studied heart rate, blood lactate, and others (stride rate and length, for instance) for a 10k run a certain rate, versus a 10k run at the same pace immediately following a 40k TT. As I said, those studies showed that the differences were evident in the first few minutes of the run, not in the second half.

I provided a link to one of those studies in my earlier reply.

This fact--that the difference is most evident in the first few minutes of the run--is why they chose to measure only a few minutes of running. Their study may have weaknesses, but I don't think there's good evidence that this is one of them.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [rubberband] [ In reply to ]

Mar 20, 08 13:14

Post #22 of 42 (3523 views)

That's my point, they did a 40k bike in that study, so it may be the beginning of the run, but it is late in the overall race. Sorry I didn't read the study, but did it also show that 73 was the same as 81 degrees? I remember one that showed that steep was better, as well a a higher cadence... Which is opposite from the study of the OP.....

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [monty] [ In reply to ]

Mar 20, 08 13:16

Post #23 of 42 (3517 views)

"Which is opposite from the study of the OP..... "

What does this tell us of the relevance of studies.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [monty] [ In reply to ]

Mar 20, 08 13:18

Post #24 of 42 (3513 views)

No, the study with the 40k TT/10k run was focused on the metabolic effects of cycling first, not on STA.

Some of the studies that showed that "steeper is better" changed only the STA, without changing hip angle, and we seem to agree that that's pretty flawed. This article fixes that, at least, but didn't replicate those earlier studies' results.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [cerveloguy] [ In reply to ]

Mar 20, 08 13:18

Post #25 of 42 (3512 views)

In Reply To:

"Which is opposite from the study of the OP..... "

What does this tell us of the relevance of studies.

I think it goes directly to the point that when reviewing studies, it helps to do more than just read the abstracts....

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [slidecontrol] [ In reply to ]

Mar 20, 08 13:22

Post #26 of 42 (1390 views)

Good thoughts. In theory you're "resting" on your skeletal system when in the aero postion but at the same time there is no getting away from the fact that your neck muscles are working harder with more cervical spine extension holding your head up. On long rides my neck and crotch always bothered me riding steep and my HR would increase as a result.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [cerveloguy] [ In reply to ]

Mar 20, 08 13:28

Post #27 of 42 (1385 views)

What does this tell us of the relevance of studies. \

That if you want any meaningfull data, you better be very carefull in selecting your criteria for that study. Since the variables that are being measured are very small to begin with, you have to eliminate as many negative factors as possible that will influence the study. The one cited by the OP is so full of holes, that it smelled of swiss cheese all the way up here. Other studies are much better, but none are near perfect just yet. First we need to get all the measuring machines to be more accurate than the +/- of the study. We are not there yet, but some of the real world studies done enough times, with enough people, do show some trends, which can be helpfull.....

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacknine] [ In reply to ]

Mar 20, 08 13:29

Post #28 of 42 (1385 views)

In Reply To:

Very interesting, will keep in mind next time I am on a stationary bike.

I'm not surprised by your derision, nor that of others. First off, I doubt more than 3 people commenting on it have actually looked at the paper. If you did, you'd notice there are pictures of both positions--and you'd hard-pressed to convince me from those pictures that one is inherently more aero than the other.

Secondly, there's obviously been an entire industry around 'steep', from bike companies to fitting certification companies--and a lot of people have bought into the idea. Consequently, anything that runs counter to that is greeted with a healthy dose of skepticism. Skepticism is good, but I'm still having a difficult time understanding why steep in necessarily faster.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [monty] [ In reply to ]

Mar 20, 08 13:30

Post #29 of 42 (1381 views)

In Reply To:

What does this tell us of the relevance of studies. \

That if you want any meaningfull data, you better be very carefull in selecting your criteria for that study. Since the variables that are being measured are very small to begin with, you have to eliminate as many negative factors as possible that will influence the study. The one cited by the OP is so full of holes, that it smelled of swiss cheese all the way up here. Other studies are much better, but none are near perfect just yet. First we need to get all the measuring machines to be more accurate than the +/- of the study. We are not there yet, but some of the real world studies done enough times, with enough people, do show some trends, which can be helpfull.....

Um, what holes? And didn't you just say that you didn't even read it??

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [roady] [ In reply to ]

Mar 20, 08 13:41

Post #30 of 42 (1365 views)

I read the summary, and that was enough.. Some of the holes:

1. Not enough time spent on bike
2. Not enough time spent running.
3. Using VO2, HR, blood lactate, all which have pretty big +/- every time you do them. More than the possible differences being measured.
4. What was the pre determined pace, vs conditioning/training position of subjects.
5. Test does not take into account any aero advantage/disadvantage, which is a biggie.

I'm not bagging on these guys, but before they can claim any meaningfull stats, you have to plug the big holes first.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [monty] [ In reply to ]

Mar 20, 08 14:03

Post #31 of 42 (1332 views)

In Reply To:

I read the summary, and that was enough.. Some of the holes:

1. Not enough time spent on bike

I'm guess I'm unsure as to what mechanism would be affected by riding for 3 hours versus 40 minutes, since muscular forces are so low in cycling. It seems to me that all it would do would be to add more variables to the equation.

In Reply To:

2. Not enough time spent running.[/quote] I think another poster address this, but the longer the subjects ran, the less STA seemed to matter. Again, I'm unsure as to the mechanism by which things would magically change an hour into a run

In Reply To:

3. Using VO2, HR, blood lactate, all which have pretty big +/- every time you do them. More than the possible differences being measured.[/quote]Fair enough--I think that testing for max wattage/pace may have been more relevant. I'll defer to some smart guy to discuss the statistical relevance of the study, though.

In Reply To:

4. What was the pre determined pace, vs conditioning/training position of subjects.[/quote] Again, it's kind of silly to be calling this a 'hole in the study' when you haven't read it... This is addressed in the paper

In Reply To:

5. Test does not take into account any aero advantage/disadvantage, which is a biggie[/quote] I'd maintain there aren't any--and I'm still waiting for someone to explain otherwise.

In Reply To:

I'm not bagging on these guys, but before they can claim any meaningfull stats, you have to plug the big holes first.[/quote] And I don't want to come off as bagging on you, but before you claim the study is full of holes, I'd suggest you read it. It's free and everything--and as a bonus, it's not in Acrobat, so you'll be able to do other stuff on your computer while it loads!!

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [tridork] [ In reply to ]

Mar 20, 08 15:30

Post #32 of 42 (1281 views)

In Reply To:

3) One would expect higher HR when the upper torso is in the aero position, since being in that position is more restrive for the torso (neck extended up, and arm tucked in to at least some extent

That, and the fact that the rider is probably supporting more weight on the arms in the more forward position, which invokes more muscle mass but this muscle mass is not making the bike go faster. Suggests these riders might fatigue or dehydrate a little quicker.

--------------
Frank,
An original Ironman and the Inventor of PowerCranks

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 20, 08 18:04

Post #33 of 42 (1238 views)

I cannot believe that this journal doesn't even give the option of downloading the papers in .pdf form. A Word document? Are you kidding? I'm now wading through a mangled piece of crap that was probably (fairly) pretty at one point on somebody's computer...

---
justin

It is difficult to get a man to understand something when his salary depends upon his not understanding it. -Upton Sinclair

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [roady] [ In reply to ]

Mar 21, 08 6:09

Post #34 of 42 (1146 views)

In Reply To:

In Reply To:

In Reply To:

4. What was the pre determined pace, vs conditioning/training position of subjects.[/quote] Again, it's kind of silly to be calling this a 'hole in the study' when you haven't read it... This is addressed in the paper

In Reply To:

5. Test does not take into account any aero advantage/disadvantage, which is a biggie[/quote] I'd maintain there aren't any--and I'm still waiting for someone to explain otherwise.

This is a combined reply to the above...

4. I agree with roady here, this is why you should READ THE PAPER before making wild and unsupportable assertions about a failure of a paper. This is clearly addressed in the paper, and whether you agree with their method should be the issue...
5. There are a number of threads here and on BTR showing a clear aero advantage to going steeper and lower in front. IIRC a poster on BTR showed a series of pics with a decrease of CdA from ~0.24 to ~0.21 by moving forwards on the seat about 3-4 degrees and lowering the front end about 5-10mm. This is approximately the difference between going 20mph and 20.8mph at constant wattage. Clearly there are more aero positions (the superman) but most of these require a very tight hip angle, which is very counterproductive. My own field testing showed an improvement of about 15W going from slack to steep at approximately the same hip angle. It isn't a myth, just do some searching here and BTR for some good aero test results.

Mad

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [triguy42] [ In reply to ]

Mar 21, 08 9:20

Post #35 of 42 (1111 views)

You saw an improvement of about 15 W more power or your new position saved you 15W aero ?

-----------------------------------------
Joel Steve
Fitter for the French Triathlon Federation
Fitter for Arkea Samsic Pro Cycling Team
Fitter for AG2R Pro Cycling Team

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [triguy42] [ In reply to ]

Mar 21, 08 16:31

Post #36 of 42 (1051 views)

In Reply To:

In Reply To:

In Reply To:

In Reply To:

4. What was the pre determined pace, vs conditioning/training position of subjects.[/quote] Again, it's kind of silly to be calling this a 'hole in the study' when you haven't read it... This is addressed in the paper

In Reply To:

5. Test does not take into account any aero advantage/disadvantage, which is a biggie[/quote] I'd maintain there aren't any--and I'm still waiting for someone to explain otherwise.

This is a combined reply to the above...

4. I agree with roady here, this is why you should READ THE PAPER before making wild and unsupportable assertions about a failure of a paper. This is clearly addressed in the paper, and whether you agree with their method should be the issue...
5. There are a number of threads here and on BTR showing a clear aero advantage to going steeper and lower in front. IIRC a poster on BTR showed a series of pics with a decrease of CdA from ~0.24 to ~0.21 by moving forwards on the seat about 3-4 degrees and lowering the front end about 5-10mm. This is approximately the difference between going 20mph and 20.8mph at constant wattage. Clearly there are more aero positions (the superman) but most of these require a very tight hip angle, which is very counterproductive. My own field testing showed an improvement of about 15W going from slack to steep at approximately the same hip angle. It isn't a myth, just do some searching here and BTR for some good aero test results.

I have just the opposite experience. At least 15W (I'd have to check my calcs to get the exact figure) going from steep to slack. Yeah, my hip angle is tighter, but it hasn't been "counterproductive". No drop-off in power and my run after the bike is just fine.

Rik

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [jacksonk] [ In reply to ]

Mar 22, 08 18:53

Post #37 of 42 (975 views)

I couldn't open it on myMac, but my only comment is that running off the bike is MUCH faster when I ride my tri-bike. When I do a long brick aff the road bike, I waddle for the first half to one mile, depending on how long the ride was. The longer the ride, the more I waddle. Off the tribike I have to restrain myself for the first couple of miles. My experience only.

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [docfuel] [ In reply to ]

Mar 22, 08 20:09

Post #38 of 42 (936 views)

Pages opened it beautifully for me on my Mac.
.

________
It doesn't really matter what Phil is saying, the music of his voice is the appropriate soundtrack for a bicycle race. HTupolev

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [roady] [ In reply to ]

Mar 22, 08 20:19

Post #39 of 42 (929 views)

"you'd hard-pressed to convince me from those pictures that one is inherently more aero than the other"

But if you posted the pictures in a "critique my position" thread, overwhelming majority here would favor the forward position. ;)

Your questions/observations and the photos are interesting. I agree that the rider at 73 degrees STA does not appear to be significantly higher than when at 81 degrees.
.

________
It doesn't really matter what Phil is saying, the music of his voice is the appropriate soundtrack for a bicycle race. HTupolev

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [HH] [ In reply to ]

Mar 23, 08 15:03

Post #40 of 42 (852 views)

In Reply To:

Pages opened it beautifully for me on my Mac.
.

Moron, here. What is pages?

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [docfuel] [ In reply to ]

Mar 23, 08 15:30

Post #41 of 42 (833 views)

Pages:
Apple's $80 answer to Microsoft's $400 office

Re: New study on the effects of seat tube angle (for those of you who care about this stuff) [acronym] [ In reply to ]

Mar 23, 08 21:24

Post #42 of 42 (768 views)

Damn! something new every day.
Will it open power point files, too?

_________________
Dick

Take everything I say with a grain of salt. I know nothing.

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