Campag4life

Proof is in the following video which is also quite entertaining.
https://www.youtube.com/watch?v=Mh0y6S5HTtc

I won't give it away but see it through to the end and you may be a bit surprised as I was.

Bottom line is rider position on the bike trumps tube shape for speed...what many already know.

canam73

Are they really ranking bikes off of 1 rider, 1 run, no mention of equalizing wheels, tires or psi and admittedly setting the handle bar heights differently?

RJM

Sure, that makes total sense. The rider's body is a much larger portion of the bike/rider hitting the wind.

Campag4life

Are you? Point is the difference between all the bikes tested is 'noise'...nebula...nada. Mostly riding position dictates aerodynamics versus the air cutting quality of tapered tube sections on a bicycle frame.
Virtually nobody here is going see much if any difference between the performance of the bikes tested.

canam73

I got your point. But you didn't make what is apparently a running series of tests with high profile bike companies top bikes shown in a ranking down to a fraction of a second. Yes, they mention the head tube difference, but that is only at the end. It takes an seasoned, observant BFer such as yourself to catch it.

shoota 

That might the most un-scientific test ever.

gus6464

If anything I would think the smallest and thinnest bike frame would be most aerodynamic since it equates to a smaller area of wind resistance.

Campag4life

Yes there are clearly many factors including Mr. H's varied aka undialed position on each bike. No doubt he is able to power some bikes better than others based upon his snap shot fit. So yes, the test is flawed. But what is does expose with all the variability subtracting reliability of the test format is just how close the bikes are together and at the end of the day the bike with the fattest non aero tube sections won the downhill.
Largely entertaining and non scientific but bottom line is there isn't a lot of difference between those bikes tested...especially say between the Venge and Tarmac and most concede the Tarmac is a better climbing bike, lighter and with a best ride quality.

Campag4life

The hole the rider punches in the air >>>>frame tube size/profile when it comes to aerodynamics. In a wind tunnel size to size the S5 is the most aerodynamic bike in the test. The dogma had a shorter headtube and lower rider position and hence a smaller hole punched in the wind for less resistance.

Looigi

Actually, considering all the variables that weren't controlled for, I'm quite surprised the times were as close as they were.

Shoot, you'd think they would have at least done multiple runs in each configuration.

Wesley36

Marginal gains are marginal. Rider position trumps pretty much everything, but even still, tight jerseys, aero wheels and aero frames make some difference.

Campag4life

In bold...I believe is the signature take away.
As to multiple runs....hmmm...maybe Mr. H is superstitious and didn't want to hedge his bets about flatting.

lsberrios1 

I wonder if bicycle companies take into the effect that the difference in rider shape can affect the aero effects of their bikes. I think aero bikes should be optimized to deflect air from the rider instead of looking which frame cuts better through the wind. I belive that bikes could be used as some sort of windshield for the rider since bikes don't ride themselves. Of course this all is dependent on shape of rider and position. In essence there is no better aero than no resistance at all, hence nothing. but when you have something behind of nothing that something becomes the un aero feature. By adding a wind deflector (bike) resistance can be lowered if the bike is shaped for it. I am sure that if you place a bike alone on a wind tunel it would do better if it had no motorcycle-like windshield, but if you put a rider on it, it would be better with the motorcycle like windshield. Then weight would be sacrificed.

link0

Although entertaining to watch, that video shows absolutely NOTHING. No variables were kept constant.

Jakedatc

Stupid attempt to be like Top Gear. even worse than Top Gear US. whatever else.. who cares.

fietsbob

If you get there first , Top of the podium, atribute it to what you rode to get there If you wish.

the Bike Companies' sales campaigns will want you to think so.. shop away Lads.

Campag4life

You don't get it. You saw nothing but others more astute like Looigi did...lol.

Campag4life

I bet you're fun at parties.

Wesley36

Yes, Cervelo uses a dummy modeled on Dave Zabriskie

wphamilton

That is a very reasonable surmise and it's not clearly wrong. In most of the possible comparisons between frames, I'm guessing that it's accurate. Yet, I've seen enough data from different tests to convince me that, at least in some cases, the aero-shaped frame has an aerodynamic advantage over a same-sized thinner round-tube frame. Even so I have to question a lot of the assumptions about aero frame shape.

One, I don't believe that head tube and downtube cross sections are truly that aero in shape. They have the appearance, but they aren't actually long enough (front to back side of the tube) for the lower-drag shapes, in other words tapering too quickly. Second, if you draw the shape on paper and visualize different apparent wind angles, at some point not very far from dead on the aero tube shape loses all advantage, and is possibly worse than a simple cylinder. Third, it's not really a static system in that the streamlines (where there are streamlines) depend not only on the immediate surface and shape but also on what the air is doing in nearby areas. And finally, how much does it depend on how you're riding a particular bike, even if you have the exact same position on each? Rocking it back and forth or steady on the rivet, how often you gun it hard, how you attack the corners and what line, maybe these (and other differences I'm not thinking of) depend on how the bike responds and maybe that also affects the aerodynamics? I think that's probably true.

On the other side, there's something about the frame transitional points, like where the head tube meets the top tube, behind the seat tube, other places. If some frames test out more aero than others, I think - and this is just a surmise - that it's in large part if not entirely due to smoothing out the air flow at these places. So there may be something there.

lsberrios1 

Thanks for the clarification. So the next logical step is to buy a bicycle based on the person the company modeled the bike after.

donrhummy

This is not even a little bit scientific and tells you nothing. Some of the MANY variables it ignores:

1. Speed and direction of the wind on each of those days

2. The exact watts he put out at every point of each ride

3. The exact angles, lines he took when going downhill

4. His weight for each ride (a person's weight can differ by 5 pounds)

5. The other components on each of the frames (wheels/tires have the biggest impact)

JasonCarp

I am betting at just over 200 lbs right now, my gravitational pull would put me under 2:00.0 on either of those bikes.

hueyhoolihan

you make a good point.

Jakedatc

Except that it is against UCI regulations to have anything resembling a fairing. which is what you are talking about.