Aero data from 19 wheels by Hambini

[hambini]

It is almost impossible for me to relate to the reported data because I only need ca. 310 watts for 50 km/h and around 90 watts for 30 km/h (FLO 60 wheels)

You must be a bit of an exception because 30km/h and 90watts is IMO quite low.

Is it possible to transform the wheels chart into time saved over a 40km loop?

It would depend on the speed you were going at or is there a generic system that people use?

Hambini

[sawyer]

Has anyone ever seen if there's difference between tubular and clincher/tubeless? Hambini said that the transition makes turbulence and since the actual tyre is sitting differently, I wonder if there's any difference in performance.

A clincher, mashed up tight against the two walls of a clincher rim, will indeed have a “flatter” rim/tire transition and has been been tested as being more aero than a tubular. If you can discern that difference while riding then you are very special indeed. But what is discernible while riding, and what no aero test will ever show is how confidence inspiring a tubular will feel as you carve that tight turn. It’s profile is round, and lays gently against a rim bed which by and large matches it’s profile and that constant round profile is much more free to conform smoothly and evenly to the road surface in all kinds of wheel contortions during turns. I suppose as tires get really big and voluminous that difference in feel gets lost and the pronounced edges of the walls of the clincher become less of a factor. But for road tires in the 23-27mm range, tubulars are still king in the handling department. Beyond that they all start feeling a bit mushy at the lower pressures they are intended to be run at. Aero really isn’t everything.

I agree with special feeling of the tubular.

I can add that my experience says that difference will become even bigger with larger tires. Try CX to understand. MTB unfortunately stopped using tubs.

I can say that even if I rarely race anymore I only want to ride with tubulars.

Agree ... in most riding conditions I wouldn't really notice the difference, but you really do notice it going down a fast twisty descent, bike is just easier to lean into corners with tubs. And then there is the no risk of blow-out advantage. More confidence inspiring downhill, and the light, flightly feeling are the two enduring advantages of tubs ...

[TiCass]

It is almost impossible for me to relate to the reported data because I only need ca. 310 watts for 50 km/h and around 90 watts for 30 km/h (FLO 60 wheels)

You must be a bit of an exception because 30km/h and 90watts is IMO quite low.

Is it possible to transform the wheels chart into time saved over a 40km loop?

It would depend on the speed you were going at or is there a generic system that people use?

Hambini

Typically 40km/h. And the time saved is in comparaison of a based wheel, typically a slow generic aluminium wheel.
It makes the data easier to relate.

[yinya]

I would be curious about the relative impact of say (a) move from standard out in front cabling to eTap i.e. remove half the cables vs. (b) go 2cm down on handlebar width vs. (c) go from alu rims like the AL33 or boyd altamont to a yoeloe C50. Realise it might be too offtopic and far from wheels only.


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[Imaking20]

I think if you look to the left at the "join date", you'll see that I registered for this forum 12 years ago (5 years earlier than you did Sure, my post count isn't high (only ~150 or so over those 12 years), but then again I really only look at this forum for non-weight related information that periodically is discussed.

Yeah, that's why I was deliberate about saying "active" and not "joined". My point was you're not totally unbiased here is all - and the timing speaks to it. Don't mean to throw too much shade, just suggesting there's more behind the energy from all sides - and it's an unfortunate distraction.

Yeah...that's the thing. Hambini may be on to something with looking at the transient response of various wheels...but, he hasn't shown anything that allows us to put anything he's done into context. Is anything he's showing even relevant or significant? Who knows?...at least not from anything he's shown so far. He gives his "gas mileage" wattage number, but doesn't give any info to show how it's applicable. It's no different than just an arbitrary "better - worse" scaling at this point.

I hear ya, but is there a "context" that would be satisfactory - other than Hambini (and co) running a more "standard" test with a few benchmark wheels to serve as a reference point? That's not meant to be rhetorical. It seems like that's what some people are asking for. Tour Magazine also provides "gas mileage" wattages for bikes and wheels, don't they? Maybe I'm just daft, but I liken these figures to horsepower numbers produced on a Dyno - they can provide some general guidance but are really only accurate against other cars tested on the same machine (and arguably same day).


As I've understood this all so far, while not meaning to speak on his behalf, Hambini doesn't think the testing protocol we've been fed is practical - so I can't fault him for not wanting to waste resources on it.

[RyanH]

For some, the gas mileage analogy works but that's still an inaccurate analogy. This is closer to being provided a single avg mpg number rather than a highway/city split. As a car buyer, wouldn't you want to know what goes into the single mpg avg to figure out if that is going to apply to your driving situation?

So, for this test, in order to do that, we need more info about the study period and what was recorded during that time.

At this point, I think we know that if you want a wheel to improve your speed (or reduce your watts) for a mixture of training, group rides and racing in general, then the test protocol and data will most closely apply to you. Others that are trying to apply this for track, road racing, TTs on closed roads and such, are still up in the air. With that being said, I don't know even if Hambini wrote up a white paper on the data gathering period we'd be able to apply the information to our own situations without him redoing the tests for those specific situations.

[AJS914]

Others that are trying to apply this for track, road racing, TTs on closed roads and such, are still up in the air.

But isn't it fair to say that deeper is faster under almost every condition. In general, the wheels seem to clump together based on size with a few exceptions like the Flo and Hunt wheels in this test. This seems to agree with Tour tests. One would have to still consider weight, and the ability to control the wheels. People probably don't want to ride 80mm wheels on group rides or in mass start races.

[natlife]

My gripe with this test has always mostly been the data that was fed into the FFT to create the protocol. I have complete confidence in hambini's ability to collect data, generate a proper protocol and run tests properly. I just feel it is missing caveats and discussions around the applicability of results.

Notwithstanding transient factors, which I totally agree with, to put it simply I believe it still comes down what kind of environment you're travelling through.

Wind tunnel testing is at one extreme on the scale and hambini's is at the other.

Nobody races in a wind tunnel, and very few people race in conditons affected by traffic as much as hambini's collected data.

If you want to know what is the fastest wheel for your commute, hambini's test is it for sure. If you're on a track, I believe wind tunnel tests are better. If you're on a closed course TT I'm not sure which would be best. And if you're in a crit, even less so.

I would love to see a hambini protocol tamed down to exclude traffic. To me that would be the most realistic protocol there is as it pertains to bike time trialing, which is what I am interested in.

[RyanH]

@AJS
Yes, I think that there's plenty enough data to establish that deeper is faster in almost any condition with a few exceptions like Bontrager outperforming deeper wheels (which seems to be consistent across numerous tests).

But, the question at hand is how deep do you want to go for mass start races or group rides and do you want to trade in the wheels you currently have? Prior to this, for example, Tour had shown that Fulcrum Quattro's, which they said were practically identical to Bora 35s, were only somewhere around 4 watts slower at 45kph than 404s. 4 watts isn't enough for me to justify the drawbacks of 404s. Hambini's test suggest much larger differences, and 30-35 watts at 50kph is something worth looking at. If it was absolutely certain that I'd see a 30-35 watt boost at those speeds for going to some deep wheels, then I'm getting me some new wheels.

[RyanH]

I would love to see a hambini protocol tamed down to exclude traffic. To me that would be the most realistic protocol there is as it pertains to bike time trialing, which is what I am interested in.

I think this would be super interesting, and I don't think we'd need all of the wheels retested, maybe just two commonly used wheels of different depths, e.g. Zipp 303 vs 808 or Enve 3.4 vs 7.8, that way we could proxy the results to get a little more context.

[ericoschmitt]

I would love to see a hambini protocol tamed down to exclude traffic. To me that would be the most realistic protocol there is as it pertains to bike time trialing, which is what I am interested in.

I think this would be super interesting, and I don't think we'd need all of the wheels retested, maybe just two commonly used wheels of different depths, e.g. Zipp 303 vs 808 or Enve 3.4 vs 7.8, that way we could proxy the results to get a little more context.

That, and those couple wheels tested with the rider in a TT position. Or maybe on the drops at 40kph (or hoods with horizontal forearms). This should be a more useful result for most people interested in racing, as nobody really rides 50kph upright, nor races at 30kph.

Most races I've been in (amateur) range from 40 to 45. Less than that means I got dropped in some climb and finished the race alone or with a small group of defeated miserable riders like me! And by then, who cares about aero?

[Shrike]

33 pages, running the risk of repeat questions at this stage but I'll ask anyway..

Have reasons been suggested for why the Bontragers are doing well? Pleasantly surprised by them.

[RyanH]

That, and those couple wheels tested with the rider in a TT position. Or maybe on the drops at 40kph (or hoods with horizontal forearms). This should be a more useful result for most people interested in racing, as nobody really rides 50kph upright, nor races at 30kph.

I inquired about that before and Hambini wasn't 100% positive but said that most likely you can adjust the results for your own CdA. You'd need to know your CdA anyway to make the results useful. Some people on the TT bike have CdA's as low as (or under 0.2). I had trouble getting mine below 0.24 without suffering seriously on the power end of things. On the track, my friend who competes at the masters Nats level had an implied Cda of somewhere around 0.16 or something silly (there's also a current in the track which pushes that number down), but it enabled him to do a lot with only 240 or so watts.

I use this to do quick calculations:

https://www.cyclingpowerlab.com/PowerSp ... arios.aspx

You can back into the numbers to get in the ballpark, I can't remember what wheel I chose but estimated CdA for test rider was around 0.34. I *think* you could estimate the CdA for the wheel you want to check, then plug in somewhere around 0.26 - 0.30 for an aggressive, arms parallel to the ground position. For quick reference:

0.34@50kph: 622w
0.30@50kph: 5558w
0.28@50kph: 526w
0.26@50kph: 494w

This is super ballpark as I think it's a little more complex to back into these numbers.

[Toby]

My gripe with this test has always mostly been the data that was fed into the FFT to create the protocol. I have complete confidence in hambini's ability to collect data, generate a proper protocol and run tests properly. I just feel it is missing caveats and discussions around the applicability of results.

Notwithstanding transient factors, which I totally agree with, to put it simply I believe it still comes down what kind of environment you're travelling through.

Wind tunnel testing is at one extreme on the scale and hambini's is at the other.

Nobody races in a wind tunnel, and very few people race in conditons affected by traffic as much as hambini's collected data.

If you want to know what is the fastest wheel for your commute, hambini's test is it for sure. If you're on a track, I believe wind tunnel tests are better. If you're on a closed course TT I'm not sure which would be best. And if you're in a crit, even less so.

I would love to see a hambini protocol tamed down to exclude traffic. To me that would be the most realistic protocol there is as it pertains to bike time trialing, which is what I am interested in.

And this is the thing; I recall this being for his friend the Ironman. I don't know which course, but some of them resemble road race courses more than most want to admit, and many others still have lots of passing and traffic and in-and-out between trees and buildings. Does it really come out to different wheels for different disciplines, or different Ironman courses? How much difference does it make in actual practice?

My head hurts, but I'd still like to see the Jet 6+, which is just a ridiculously good deal and popular with triathletes and hopefully performs well.

[Beaver]

33 pages, running the risk of repeat questions at this stage but I'll ask anyway..

Have reasons been suggested for why the Bontragers are doing well? Pleasantly surprised by them.

In the end a round shape and fulfilling the 105% rule seems to help after all: the Bontrager are 27mm wide outside, 19.5mm inside, with a 23mm tire that's quite a good match.

And Hambini added the new Light Bicycle rim with 30mm outside, 23mm inside - this is also quite good, especially at high speed: