does anybody know of a site or study in which aero frames have been tested against non aero frames WITH RIDERS ABOARD and built up with wheels and such? i have read the material here at s-twitch and cervelo and cobb's site. unless i am missing something these sites are not quoting figures from actual identical bike/rider combos with the tubes as the only varible. the s-twitch site, for example states mr empfield went to the tunnel with an armful of tubes alone, as i recall it. thinking of the infamous "aero seatpost" non-finding of mr cobb's where such posts were actually LESS aero with a pedalling rider but MORE aero by themselves i am given to wonder why that might not be the case for aero seat TUBES as well, for example. i know they look cool and all, and there is a certain intuitive credibility, and lance rides one, etc etc, but is there an actual test of xxx frame/rider and then yyy frame/rider with the varible on said combination the flattened tube? frames and/or tubes alone don't seem that comprehensive a test to me. i am thinking of a tri geometry bike, but there are several attributes i like better in a round steel tubed bike as opposed to the aero alu tubed ones i have been on (barb lindquist seems to do ok on hers.....). before i give up some things i really like beter, i would like to know if it is really for something measurably better, or just perceived so. thanx.
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Re: seeking specific aero data [t-t-n]
[ In reply to ]
Good questions. I'm not aware of any site that specific. Here is the url for Jim Martin'e site, which like that on the Cervelo site is quite theoretical. You might call/email Martin or Cobb and see how much info they are willing to volunteer. Also Gerard is supposed to be doing some aero testing at MIT this winter. Looking forward to picking his brain when this gets done. http://home.hia.no/~stephens/aero.htm
Re: seeking specific aero data [t-t-n]
[ In reply to ]
Careful t-t-n, you're treading on thin ground and in danger of exposing a lot of marketing mumbo-jumbo for exactly what it turns out to be...ill informed hype. I'm not suggesting various companies are lying or even trying to purposely mislead us. Most are doing stringent tests. But, like you pointed out sideways, none of it is standardized. You want to know what you'll be more aero on, bottom line. I do too. I think you'll be hard pressed to find an accurate and well executed test protocol that will answer that question definitively. The trouble is that none of us with no stake in the bike biz other than as consumer don't have the $$ to go out and conduct such a test. As such we are dependent on others with more stake in the biz to tell us the aero facts. Again, I'm not suggesting that anyone is lying here. Just that one is usually comparing apples to oranges when comparing numbers from the different tests done. And so far I haven't found anyone who has put the entire package together to answer the questions you seem to be asking. At least not that is readily available to the public.
Re: seeking specific aero data [cerveloguy]
[ In reply to ]
thanks, cerveloguy. i think i might just do that. indeed, to me it is kind of a no brainer that any such test would have to have a rider on board and even have that rider PEDALLING, to be valid. imagine a guy on a bike in a snowstorm and the drift that would form around him holding still. now imagine the same guy pedalling in the snowstorm. it seems to me that the dynamic of airflow would be radically different! hence, any aero frame qualities would be radically different.
Re: seeking specific aero data [t-t-n]
[ In reply to ]
From what I got out of it, Cobb does not think aero posts are bad, just the aero posts that do not fill in as much area as possible as in the case of Giant and Corima.
Cervelo, Trek and the BP Blade posts are wider and more shaped like a foil, and they take up more room between the riders legs while remaining aero.
I just ordered a BP Blade aero post ($110, 250gms, 300mm tot, 27.2 dia) from www.bikeparts.net, they are not willowy like the Giant, they are 27.2mm wide and shaped like a foil and look alot like the cervelo's posts, a good option i think for my Santa Cruz, a bit heavier than the USE but according to Cobb - more aero - less willowy.
Cervelo, Trek and the BP Blade posts are wider and more shaped like a foil, and they take up more room between the riders legs while remaining aero.
I just ordered a BP Blade aero post ($110, 250gms, 300mm tot, 27.2 dia) from www.bikeparts.net, they are not willowy like the Giant, they are 27.2mm wide and shaped like a foil and look alot like the cervelo's posts, a good option i think for my Santa Cruz, a bit heavier than the USE but according to Cobb - more aero - less willowy.
Re: seeking specific aero data [t-t-n]
[ In reply to ]
Quote:
it seems to me that the dynamic of airflow would be radically different! hence, any aero frame qualities would be radically different.Exactly t-t-n. When we have that test, with a good range of current bike and gear setups, we will be able to make truly informed choices based on proper and standard test protocol. Maybe then we can get past just the aero aspect and start putting all the factors together in making choices about which bike/setup would we be fastest on. Its either that or become Lance Armstrong and get personal attention in a wind tunnel. Cobb and others go a long way toward getting us there, but their tests are still conducted over a very specific set of criteria. It doesn't take an engineer to see that a Cervelo or Softride is probably more aero than a standard lugged frame or that an H3 is more aero than a 28 spoke Open Pro when standing alone or just mounted on a bike with no rider. But how much does it really matter when you put the dynamic of the rider pedalling into the mix. Some companies have indeed provided numbers intended to answer this question. But by and large, we (the consumer) are still guessing at whether model/setup x or y is the faster bike with us on it, all other factors (fit, tire pressure, tyre type, etc) being the same.
Re: seeking specific aero data [t-t-n]
[ In reply to ]
Aero drag measurements made with a rider aboard:
1) the famous "shoot out" at Texas A&M that used Colby Pearce as the test subject.
2) all the Project 96 tests.
3) almost anything Chet Kyle did back in the 1980's.
4) at least some of Cervelo's tests.
1) the famous "shoot out" at Texas A&M that used Colby Pearce as the test subject.
2) all the Project 96 tests.
3) almost anything Chet Kyle did back in the 1980's.
4) at least some of Cervelo's tests.
Re: seeking specific aero data [Anonymous]
[ In reply to ]
anon. that is interesting. do you by chance have any other leads on these? sites? maybe i will keep seaching. thanx. as an aside are the '96 bikes the ones with no top tube that were very aero by report but faired less than stellarly in competion? any further references would be great if you have them handy.
and to tribri, maybe the kyle tests had what we are talking about, i will keep looking. really tho, i don't see what would be so terribly difficult about it and so it does make a fellow wonder. with apologies to mr empfield i just don't see the point of testing an armfull of tubes. similarly i don't see any real point in testing a bike without a pedalling rider and spinning wheels - i could well be missing something, and if so i am asking for clarification.
i am not trying to disprove anything, or be argumentative on the topic. like i say, i'm starting to think about a new frame, and i like a lot of things about small round tubed steel bikes in the practical sense. but i would consider foregoing some of those things if there was a decent enough measurable tradeoff in less dense wing shaped tubes - so long as it makes sense to me as having real world application. thanx again for the leads.
and to tribri, maybe the kyle tests had what we are talking about, i will keep looking. really tho, i don't see what would be so terribly difficult about it and so it does make a fellow wonder. with apologies to mr empfield i just don't see the point of testing an armfull of tubes. similarly i don't see any real point in testing a bike without a pedalling rider and spinning wheels - i could well be missing something, and if so i am asking for clarification.
i am not trying to disprove anything, or be argumentative on the topic. like i say, i'm starting to think about a new frame, and i like a lot of things about small round tubed steel bikes in the practical sense. but i would consider foregoing some of those things if there was a decent enough measurable tradeoff in less dense wing shaped tubes - so long as it makes sense to me as having real world application. thanx again for the leads.
Re: seeking specific aero data [t-t-n]
[ In reply to ]
hmmmmmm. well maybe i am barking up the wrong tree. i do not see where anybody specifically says that tests "with riders" means that they are actually pedalling during the test. honestly it seems like it would make a pretty big difference to me. maybe this is impossible to do - would the pedalling motion somehow prevent measuring of drag in the tunnel ?? anyway, i'll keep looking, as it is gonna bug me now. :)
test protocol
[ In reply to ]
At Texas A&M, riders are pedaling, and the front wheel is spun at 30 mph by a roller recessed in the wind tunnel floor. The resultant noise in the data is eliminated via signal averaging techniques. Chet Kyle, in contrast, prefers to test with rider's legs stationary, but positioned at all possible angles. This is how the Project 96 data were generated.
Re: seeking specific aero data [Anonymous]
[ In reply to ]
add to that tests with ken glah and mike pigg at a minimum. cobb and hed have been testing with riders aboard for more than a decade. they both tend not to publish, however. in hed's case it's because it's for his own personal use, and in cobb's case it's because he's getting paid to perform the test by softride, kestrel, shimano, etc., and they own the results.
Dan Empfield
aka Slowman
Dan Empfield
aka Slowman
Re: seeking specific aero data [Slowman]
[ In reply to ]
The german magazine "tour" has performed testing of a number of aero frames with a rider on the bike. The data is in watts saved at a certain speed. www.catbikes.ch has the results
Tour results
[ In reply to ]
Simply put, having done similar experiments myself, I don't trust them.
Re: seeking specific aero data [steady]
[ In reply to ]
thanx for the info, guys !
Re: seeking specific aero data [Slowman]
[ In reply to ]
I know these tests are being done, Dan. But we, as consumers, don't get to see the results and numbers. Instead we have to rely (and certainly not without good reason) on somewhat nebulous statements like "a disc is fastest on the rear." Why? Because I (whoever it is) measured it and that's what I found. Well, duh. No one is arguing that. But did you do your test the same as so-and-so who tested brand x disc? If so, which one is faster? We never see objective results of tests of fork vs fork that aren't somehow tied to one company or entity or another. The only way we have of determining with any certainty that we are faster with one set of wheels or one fork or even combination of wheel/fork or whatever over another setup is to pay a lot of $$ for time in a wind tunnel, not to mention $$ to have all the parts under consideration on hand. That is overkill for your average AG.
Re: seeking specific aero data [steady]
[ In reply to ]
What I find interesting from the site is this.
"...The list shows how much energy aero frames can save. Surprisingly, the shape of the frame made little difference. Riding position and wheels are more important."
The words uttered from Tom D. "Stop comparing bikes and start comparing fit!" come to my mind.
"...The list shows how much energy aero frames can save. Surprisingly, the shape of the frame made little difference. Riding position and wheels are more important."
The words uttered from Tom D. "Stop comparing bikes and start comparing fit!" come to my mind.
Re: seeking specific aero data [TriBriGuy]
[ In reply to ]
tribriguy. i think the solution is very easy, has ample precedent, but sadly will never come to be. magazines. triathlon, inside tri, whatevertrimonthly. this is what those guys should freaking doing, iff'n you ask me. the precedent could be found in things like motorsports mags, where they DO this sort of testing all the time. magazines have the access, and the wherewithal to get it done, or they should. obviously there are industry problems, probably revenue and advertising issues, and other stuff preventing this.....but still. the late, great bicycle guide magazine used to do this sort of thing only 12-15 years ago or so. just imagine how cool it would be for consumers and the sport if the modern tri mags did so with the sort of issues we are discussing today. . . .now, just why is it you suppose they don't ???? mr empfield ??????
Re: seeking specific aero data [Luntzy]
[ In reply to ]
Luntzy, secretly I agree with you when you quote Tom about comparing bikes. I guess what I'm getting at is that I think that standardized tests will show that we are mostly wasting our $$ chasing speed. After putting aero bars and wheels on our bikes, the other stuff is splitting hairs for mere seconds, but it sure costs a mint. For those athletes pushing the envelope, yes, a few seconds here or there will make a difference. For most of us however....when we start to see how little difference those lusty new forks, wheels or frames are really going to make compared to our current setup, especially when we put our own non-aero bodies on the bike, we might think twice about where we're putting our $$. Better fit and better motor are better bets for spending $$!
Re: seeking specific aero data [TriBriGuy]
[ In reply to ]
" Its either that or become Lance Armstrong and get personal attention in a wind tunnel." He, is becoming like Lance an option? I figure I have a better chance of that (in my dreams anyway) than of ever seeing companies revealing their own test data that might not be quite so flattering to their "aero" machines. Also, I can imagine the big pile of poop they'd be in if they made an ad up that showed their test vs. the competitors and someone else came up with different numbers.
Re: seeking specific aero data [t-t-n]
[ In reply to ]
On magazine testing: My guess would be expense. Motorsports mags can afford to test on a closed track because the auto industry supports it. The bike industry is not in such great shape. Rodale just turned mountain bike into an eight issue supplement to Bicycling, and Bike magazine just fired a couple people. Back in the mountain bike hay-day I remember some empirical testing in Bicycling, and some euro bike mags, measure frame stiffness, but renting out a wind tunnel to do a comprehensive study on a large enough sample of frames would be insanely expensive.
On aerodynamic testing: Testing the rider while pedaling will improve understanding of aerodynamics, but not of efficiency. Lets say I improve my aerodynamics by making my frame half as wide; 34mm bb shell, tubing at max 15 cm wide. Aside from the pain it would be to find a bb, I would have a bike that would either be at least twice as flexy or far heavier. If I was to test this bike while pedaling in a wind tunnel the test would show that I should be way faster in a race. Take it outside and you will quickly find the bike to be nearly unrideable. Cars separate the duties of aerodynamics, power production and handling between the engine, frame and body. Cyclists do not have that luxury, unless you choose to give up all pride and start racing HPV’s. If frame flex and stability comes into play the only way to really test bicycle effeciency is to actually ride the stuff.
While the talk is on aerodynamics, does anyone out there know what kind of research has gone into the fork crown region? Since a rider who is going thirty mph has a wheel that is traveling a virtual 60mph at the top of its travel this seems to me a problem area. To make matters worse, this is an unusually crowded area of a bike, fork crown, headset, front brake all interfering with the front wheel. Is there anything done to address this? Would running a front disc brake provide an advantage?
On aerodynamic testing: Testing the rider while pedaling will improve understanding of aerodynamics, but not of efficiency. Lets say I improve my aerodynamics by making my frame half as wide; 34mm bb shell, tubing at max 15 cm wide. Aside from the pain it would be to find a bb, I would have a bike that would either be at least twice as flexy or far heavier. If I was to test this bike while pedaling in a wind tunnel the test would show that I should be way faster in a race. Take it outside and you will quickly find the bike to be nearly unrideable. Cars separate the duties of aerodynamics, power production and handling between the engine, frame and body. Cyclists do not have that luxury, unless you choose to give up all pride and start racing HPV’s. If frame flex and stability comes into play the only way to really test bicycle effeciency is to actually ride the stuff.
While the talk is on aerodynamics, does anyone out there know what kind of research has gone into the fork crown region? Since a rider who is going thirty mph has a wheel that is traveling a virtual 60mph at the top of its travel this seems to me a problem area. To make matters worse, this is an unusually crowded area of a bike, fork crown, headset, front brake all interfering with the front wheel. Is there anything done to address this? Would running a front disc brake provide an advantage?
I think along the same line as allan, but take it to a new limit go talk to John Cobb convince him to setup time at A&M (pick up the tab) ask him to bring some parts and maybe a few bikes, Get Tom Demerly and Dan Empfield to go with you (pick up the tap). Get them all to fit you in the most aero position possible. (The Kicker) keep the data to yourself and use it to beat us all. Simple plan just expensive.