I will have to disagree with you. I know for a fact that I ride my P3 about 1 to 1.5 MPH faster with my Zipp 404's on in the place of my Kysriums. And that is riding at the same heart rate with both sets of wheels. How much diference does the P3 frame, and the HED bars, and the ouzo pro aero forks and so on make? I do not know, however I like them and that helps the mind. As for the wheels that is how the stats stack up.....

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"You're guaranteed to miss 100% of the shots you never take" - Wayne Gretzky

I have a Zipp front and a rear J-disc and I ride faster too, but when do I ever put them on except when I intend to ride faster? They are also lighter weight, which way enter the equation as well. I would like to hear from someone who could say, "On my old bike at 200 watts I used to ride 22 mph and then I switched over all my gear to the new frame and the next week for the same 200 watts I was riding 23 mph.

Anybody out there who can say that?

Like I said. I have a power meter coming and I intend to test it. But my hypothesis is that "aero" stuff is mostly advertising.

Some of this hypothesis has to do with my limited knowlege of the steep curve in wind resistence when you pass 25-30 mph. At that speed a little drag can really slow you down. For the 15-25 mph crown (i.e. 90 percent of us), even major changes in aero drag just don't make as much difference.

Chad

Q: What do all the companies selling aero bikes and equipment have in common:

A: They want you to take money out of your pocket and put it in their pocket.



Although ceramic bearings, carbon seat stays, and various aero devices are marketed as engineering advances, I'd bet many were engineered in the marketing department. It's easy to make a sales pitch to someone who wants to buy something.

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

I believe you wanted to know if we are all suckers for buying Aero Equipment... I say no, and by the way my Zipp 404's are clinchers and are about the same weight as my Kysrium's, so weight is not an issue here.

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"You're guaranteed to miss 100% of the shots you never take" - Wayne Gretzky

The other thread on the front page today: "$4500 to spend" undoubtedly has some marketing guys thinking something like, "Bet there's a market for aerodynamic carbon fiber bar end plugs."

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

I believe the aero stuff helps but some of it not as much as is claimed.

Look at the Kona times. There is not a men's post 1996 top ten bike time in the top ten times. It's similiar for the runs/swims but one would assume that the bike times should be compensated for by the so called aero improvements. For the women, Paula's 1993 bike time is still the fastest. For the most part, these times were on round tube frames.

Problem is, few people are aero testing bikes and most of those that are couldn't be considered unbiased.

cdwalton wrote, "Some of this hypothesis has to do with my limited knowledge of the steep curve in wind resistance when you pass 25-30 mph. "

This is not correct. There is no magic point where there is a sudden rise in wind resistance. The power required to overcome aerodynamic drag goes as the third power of speed for all speeds. So to increase speed by 20% takes 73% more power regardless of the original speed. So depending how one looks at it, one could say it takes less power to increase speed at higher speeds. Going from 15 to 18 mph takes an increase in power of 73%. To go from 25 to 28mph only requires 41% more power.

Also, I don't have the numbers available here, but even for speeds as low as 15 mph, on level ground, the greatest resistance to motion comes from wind drag. [O.K. I checked the numbers, at 15 mph 64% of the power goes to overcome drag; this rises to 80% at 28 mph]

Quote:

This is not correct. There is no magic point where there is a sudden rise in wind resistance. The power required to overcome aerodynamic drag goes as the third power of speed for all speeds. So to increase speed by 20% takes 73% more power regardless of the original speed. So depending how one looks at it, one could say it takes less power to increase speed at higher speeds. Going from 15 to 18 mph takes an increase in power of 73%. To go from 25 to 28mph only requires 41% more power.


I don't know how you came up with this formula, but it sounds flawed to me based off of real world experience. I can increase from 15-18 miles per hour and not break a sweat, but if I try to go from 25-30 miles per hour I'm going to last about five to 10 minutes before I blow up. The wind resistence at 30 mph is huge, which I believe is why all the wind tunnel testers use that speed because differences in aerodynamics are more readily apparent. The curve goes even higher above 30 mph and it is because the wind resistence increases steeply. Why else would riders of normal ability but with large brains that developed cool fairings be able to pedal 60 mph on a bike when Mario Cipollini maxes out at about 45 miles per hour in a field sprint in the Tour de France?

People that buy aero gear (I should just raise my hand because I am one of them-I bought Visiontech and Cervelo) that was tested at 30 mph are deluding themselves if they think they are going to derive the same benefit at 20 mph. I read one of the Cervelo marketing people say one time that the 15 mph rider actually benefits more from the aero tubing because they are out on the course longer. That is preposterous. The wind resistence/turbulence created at slow speeds is just not that great.

Chad

This is my thought

First buy a set of aerobars and get a good fit. Your body is the biggest thing on your bike and making it see the air less will make you faster. Second get a good set of aero wheels. Wheels move and turn up a lot of air. There for wheel disc, trispoke, deep dish good. Other than that I don't see where a frame can make that much diffrence.

As far as the slower you go the less drag I have to go with this. It only make perfect sense. I have used this example before so stick with me.

When an airplane slows down it must deploy its flaps to keep enough lift to help the plane fly. The flaps give the wing more surface area there for increasing lift. At higher speeds more pessure is placed on the wing needing less wing area.

Get a good fit, good wheels and train smart. That's all you really need.

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customerjon @gmail.com is where information happens.

Goddamn kilogram! Did cd touch you in a naughty area?

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customerjon @gmail.com is where information happens.

> I don't know how you came up with this formula,

sorry. The source was http://www.analyticcycling.com If these results seem flawed based on your experience, you need to recalibrate your experience based on measured data. The models at analyticcycling.com have been validated against actual instrumented riders.

As to the rest of what you wrote, maybe you should review some of the writings on bicycle aerodynamics. There are articles at slowtwitch, Kraig Willett has articles at bike.com and the ones at analyticcycling.com are also good.
You confuse perceived effort with power. It is well known that peceived effort increases steeply as one exceeds lactate threshold, this is not the same as power increasing to the same extent. So yes it feels easy to increase speed from 15 to 18 mph because you are riding well below threshold. The fact that you can hold 30 for only 5-10 minutes means you are approaching V0_2 max power.

Finally, you take issue with the claim that the 15 mph rider saves more time than the faster rider from aerodynamic improvements. Unfortunately, this is exactly true. Both are operating in the same Reynolds number regime so the turbulent nature of the flow is the same for both cases. In terms of fluid dynamics, the speeds are not that different.

I think that you are right on... I bought a pair of Reynolds carbon wheels last year- 1400.00 plus... going to go real fast. I went about the same speed. Found out that you had to take the tubular tire off to true them (OK I am a little slow sometimes, should have got that earlier...) what a waste... sold them on Ebay. No way I send that much again. I don't think that you get much faster on aero frame, wheels ect... Unless lightening the wallet helps.

Another simply little testing method to see if your areo stuff works. Find yourself a good hill & coast down the hill (don't even pedal to get rolling) take note of speed at the base of the hill.Go back up to the top again put on your aero gear & coast down the hill again (be sure to have your body in the same position). See if there is any speed difference.Maybe even do a few passes to get an average terminal speed then change to your aero gear and repeat.

I read about this method somewhere as a good little test, they were refering to body positioning though but I guess the same principal applies. If it's a good enough hill where you can at least coast down at 40+km/h then maybe you can see a difference.

I guess this method could work ok.

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http://www.velokyniska.com

"Ah yes - your real world experience clearly trumps tested and proven physics."

I am also a man of science and and a practical engineer type so understand where you're coming from. However, my "real world experience" does not coincide with with the formulas provided for aero improvements with bikes.

I also realize that there are factors that can't be measured in "real world experience" such as winds, motivation that day, yadayadayada. So it's impossible to do a legitimate controlled study under "real world" conditions.

> So it's impossible to do a legitimate controlled study under
> "real world" conditions.

Maybe it's impossible without considerable effort, but it is not only possible but has been done with a rider on a bike with an SRM on a (I believe, indoor) velodrome. The results were reviewed and published (Martin et al. J. Appl. Biomech. 14,3 (1988)).

 Just jumping into this post now, but the rationale behind this statement is flawed "Going from 15 to 18 mph takes an increase in power of 73%. To go from 25 to 28mph only requires 41% more power"

Yes, that statement is true. However, if you look at the raw wattage required, you need substantially more power (expressed as watts) to increase speed by 1 mph at a higher speed rather than a lower speed.

Playing with the models at analyticcycling.com, it takes an extra 28.8 watts to pedal at 8 metres/second rather than 7 m/s. It takes an extra 86.8 watts to pedal at 14 m/s (approx 31 mph) rather than 13 m/s. The drag forces are considerably larger at higher speeds.

My theory, untested of course, is that aero wheels offer a significant effect, and frames less so, because of one significant difference. The very top of a wheel is moving forward through the air at double the velocity of the bike, and any given segmet of the wheel above the hub is moving at some multiplier between 1 and 2 times the velocity of the bike.

Say you have a 58mm deep rim front wheel, with a 23 mm tire (700c). The section of the wheel which is travelling between 1.75 and 2 times the velocity of the bike looks like a disc wheel to the wind. That is why aero wheels are so effective (I think anyway)

Anecdotal evidence, my best TT's have all come on big, fat oversise aluminium framed bikes (Cannondale and Klein). My TT's on the Cervelo P2 were generally not as good, not the bikes fault, mostly fitness, but if the frame made as much difference as the claims I should have been at least equal on it. and no, my TT position hasn't changed in years.

My 2 cents, FWIW.

J.

jasonk Wrote, "Just jumping into this post now, but the rationale behind this statement is flawed 'Going from 15 to 18 mph takes an increase in power of 73%. To go from 25 to 28mph only requires 41% more power'"

No, the rational is not flawed, what you quote is a statement of fact (the fact being the result of a model simulation). According to the model, it does take 73% and 41% more power for the two cases. Now what significance to put to this results is open for discussion, but the results are what they are. If you read my original post I made a point of saying this was only one way of looking at the data. I chose it to illustrate that there is no magic point where aero drag kicks in and below which it is insignificant.

However, This illustration may be relevant for a real rider. Lets say you just did a 40K TT at 15mph and ask me how much you have to improve to run 18mph. I can tell you you'll need to improve threshold power by about 71%. On the other hand if you did the TT at 25mph and ask me the same question, I'll tell you you need to improve by 41%.

I'm not saying now (nor did I previously) that this is the best or only way to use the model or consider the relation between speed, power, and drag. I'm just saying it is one way, and the one I used to illustrate a point

If you read my post again, I agree with you that the numbers are accurate. But, it takes about 2.5 times the power increase to go from 25-28 mph as it does to go from 15-18 mph. So the 41% improvement is actually significantly more difficult than the 71% improvement.

I agree that there is no magic point that drag kicks in. But there must be a "zone" somewhere (I don't pretend to know what that zone is) where the drag of the frame becomes significant enough that changes to the aerodynamics of the frame are discernable (ie repeatably measurable) above the environmental "noise". To take it to the extreme, to increase from 1-3 mph might require a 400% increase in power. (I made up that number, don't take it for gospel) But you're still only talking about maybe 10 watts. That 10 watts is easily obscured by a gust of wind, a change in the road surface, tire pressure changes, or any one of a host of other factors.

My point is only to try to point out why people's "real-world" observations do not necessarily jive with the scientific studies. I think the studies are valid, but at the speeds most of us ride at we may not notice a dramatic effect from the fancy frame to the extent that we do from the fancy wheels.

I'll chime in as well.

what cdwalton said was this: "Some of this hypothesis has to do with my limited knowledge of the steep curve in wind resistance when you pass 25-30 mph. "

When I thing about this, I see a graph with an x axis of speed and a y axis of power. As you know, increase in power required ans speed or velocity increases is not linear, but exponential. Drag is calculated, in part, my using (V^2/2), where V = velocity. So the line on this graph gets "steeper" the further right or "faster" you go.

So there is a curve, and the further right you move, the steeper it gets. cdwalton didn't mention a "magic point", you did. Maybe you misread his post, but it makes sense to me. The line as it passes 25, 26...30 Mph, etc., is "steeper" than it was at 15, 16...20 Mph.

just my $0.02

I am signing on from home but it is still me, who started the post. I appreciate most of the comments and have a few of my own in return.

To Asgelle--I apologize if I made it sound like you didn’t know what you were talking about. Quite the contrary, I am not a number cruncher and stopped trying to fly airplanes because of it. However, JasonK explained what I was trying to get at in the first place. It takes substantially more power (in his example nearly three times as much) to increase your speed at higher rates of speed than lower. I suspect if you plotted the relationship on a curve, the watts needed would rise steeply after about 20 mph until by 35 miles per hour only Lance and Jan can maintain them for any length of time. This is why it doesn’t make since to kill yourself in your 54x12 going down a hill. Just tuck, coast and use your energy more sensibly at the bottom.

To Jason K--thanks for posting some info that was a little more scientifically based than just my hunch

To Cerveloguy--I agree that a real world test can’t be perfect, but it should be able to tell you something. If I go out on the same day and ride the same course on two different wheel sets at the same power output, I ought to receive some useable feedback. If I do the same thing every day for five days then I should be able to spot trends. If I can’t then it will be fairly clear that none of the gear is clearly superior to the other and that will take me back to my original hypothesis--why spend money on something that does not very clearly make you go faster?

To RipVanWinkle--I’m not the least bit embarrassed since it was just my opinion, to which I am entitled. Apparently, there were at least as many people who agreed with me as did not. Your post however, added nothing to the discussion. Not you or anyone else yet has stepped forward to say that they have used a power meter to measure actual output (on the road, not in a lab) and that their aero bike made them faster.

Still waiting.

To JohnA--thanks for using the word that I have been trying to dredge up from the depths of my memory--exponential. Yours was a great explanation of what my “real world experience” was telling me.

Chad

well as I read english, the statement, "... steep curve in wind resistance when you pass 25-30 mph ..." implies there is a difference in the behavior above 25-30mph from that below 25mph. What I'm saying is that there is no difference in the qualitative behavior of drag relative to speed from the slowest to the fastest speeds normally achieved on a bicycle.

While the steepness of the drag (or power) vs. speed curve may increase in absolute value as speed increases, the steepness of the curve relative to speed (the slope of the function) is the same for all speeds. The aero drag vs. speed curve has slope proportional to the speed and the power to overcome aero drag vs speed has slope proportional to speed squared. That allows us to say the proportional change in power required for the same proportional change in speed is the same for all speeds (considering only aero drag).

Your problem isn’t one where companies are lying to you. In fact their tests are quite accurate and it does translate into real world results. Your problem is one of context. No company will give you context; they just give you the results when it makes their product look better than an alternative product. The results are true and accurate mind you, they are just not in context. You have to figure out (and you’re figuring it out right now) the context.



So here is a very basic priority list when it comes to the bike. Power trumps aero, aero trumps weight. In essence power trumps everything. So the question is do you generate enough power for your size (a primary determinate in aero)/weight? If the answer is no, then you have to look at getting yourself into the right ratio of size/weight to power, to whatever that is for your competitive arena. So you may have to increase power, reduce weight, get more aero etc. Right now the answer is “I have no idea because I don’t know my power.” But that is changing because you are getting a power meter. Guess what? You are moving in the right direction. I would say that was the right choice as opposed to an even more aero frame, because power trumps everything.

Ultimately you are trying to adjust all of the variables around so that they fit into your context, whatever that is based on your goals. If your power is severely lacking because of fitness or bike fit or whatever, then all the aero equipment in the world will not have much effect. However if your power is ok and your position is good (which is most of the aero stuff anyway), then you have to start looking at weight. If your weight is good, then you may have to look at aero again or increasing power. And so it goes. The aero equipment is important, but it’s not the foundation on which you build your success.

I haven't bothered reading all this scientific bullshit but I was just talking to someone about this the other day. With recent upgrades here are my supposed savings over 40km from claimed data ;

Reynolds Ozo Pro Aero fork 55 seconds

Disc Wheel 2-3 minutes

Vision tech bars 1 minute

My best time for 40km is 1.01 and it is still 1.01 after the upgrades despite several attempts to better it. Have I got 4-5 minutes slower all of a sudden ? I doubt it.