Aero data from 19 wheels by Hambini

[tanhalt]

I have looked, and I don't see an answer from you that's decipherable...so, to save any confusion that may result from a misinterpretation (a common problem on the internent, no?) how about just telling us what that vertical scale on that plot actually means? Again, you are leaving context out of your plots.

Anyway, I don't get this agressive pettiness towards me that you've displayed throughout this entire thread. I've merely calmly asked questions about the protocol and measurements in an attempt to put them in context. All it's been met with from you is appeals to authority ("I'm the EXPERT here, TRUST what I say!"), ad hominem attacks, and obfuscation. You throw up plots with undefined axes and then expect people not to question it...and if they do, you accuse them (falsely) of being "shills", or worse...WTH?

Why are you afraid of questions? If this protocol you've developed IS better than what has been previously done, you should WELCOME questions as opportunities to explain and demonstrate why that is so. Shouting down legitimate questions with nothing but insults and appeals to authority isn't a good way to make your case or win people over...

As mentioned previously. Umpteen times. My primary job is not in the bike industry and therefore the resources that myself and my colleagues spend to answer questions is limited. I/We have tried to be accommodating where possible.

I can't be expected to give engineering principles lectures on weightweenies posts because you don't understand something. I have suggested you speak to your friends at Specialized to see if they can assist you with your questions, or speak to mr Coggan, he seems to know everything.

Thanks

Hambini

OK...more obfuscation and deflection

Don't forget that the purpose of a forum is for multiple people to learn from your answers, not just myself. If I wanted the answer to myself I could just DM you to ask.

At this point, we'll just have to assume there's a reason you don't want to reveal more details about your initial data gathering and your test result presentations...

The "rankings" you produce aren't worth anything without context. You haven't shown any.

[ericoschmitt]

I have looked, and I don't see an answer from you that's decipherable...so, to save any confusion that may result from a misinterpretation (a common problem on the internent, no?) how about just telling us what that vertical scale on that plot actually means? Again, you are leaving context out of your plots.

Anyway, I don't get this agressive pettiness towards me that you've displayed throughout this entire thread. I've merely calmly asked questions about the protocol and measurements in an attempt to put them in context. All it's been met with from you is appeals to authority ("I'm the EXPERT here, TRUST what I say!"), ad hominem attacks, and obfuscation. You throw up plots with undefined axes and then expect people not to question it...and if they do, you accuse them (falsely) of being "shills", or worse...WTH?

Why are you afraid of questions? If this protocol you've developed IS better than what has been previously done, you should WELCOME questions as opportunities to explain and demonstrate why that is so. Shouting down legitimate questions with nothing but insults and appeals to authority isn't a good way to make your case or win people over...

As mentioned previously. Umpteen times. My primary job is not in the bike industry and therefore the resources that myself and my colleagues spend to answer questions is limited. I/We have tried to be accommodating where possible.

I can't be expected to give engineering principles lectures on weightweenies posts because you don't understand something. I have suggested you speak to your friends at Specialized to see if they can assist you with your questions, or speak to mr Coggan, he seems to know everything.

Thanks

Hambini

But then the time you spent writing answers like this could have been used to tell us what FSR means among other things.

[otoman]

Many thanks to Hambini for taking the time and the effort to do the tests and produce something that is meaningful and free of signifiant bias.

It is an interesting scenario that aerodynamics is discussed so much in the cycling world yet on these forums there are few people who are professional "aerodynamicists". You won't find them on slowtwitch either. It's basically the same reason that there is not a chance in hell that I'm going online to some WebMD forum to explain ear infections or sinus infections to a bunch of amateur/hobbyist "physicians" (I'm an otolaryngologist). I'm surely not going to publish my research online to WebMD first... So when Hambini comes on here and gets pounded on by a couple of people who, in their defense, are trying to act like a peer-review process, I can see that it would get old quickly trying to defend some work in a forum that is not a legitimate source of peer review. It then begs the question, why did Hambini do the work and post here at all? It seems he was curious and wanted some answers for himself and was willing to share the data. There were words to that effect previously. Perhaps some alterior motive will be exposed on GCN, haha.

Basically, what I'm getting at is that tanhalt and WMW, you've made your points, you don't feel that hambini is transparent enough, throwing the data and results in to question. From your point of view, can't say I blame you. Hambini, you feel that these people are not your "peers" and therefore not able to offer meaningful critique. From your point of view, can't say I blame you.

Great, that is settled. Moving on....

[bilwit]

Many thanks to Hambini for taking the time and the effort to do the tests and produce something that is meaningful and free of signifiant bias.

It is an interesting scenario that aerodynamics is discussed so much in the cycling world yet on these forums there are few people who are professional "aerodynamicists". You won't find them on slowtwitch either. It's basically the same reason that there is not a chance in hell that I'm going online to some WebMD forum to explain ear infections or sinus infections to a bunch of amateur/hobbyist "physicians" (I'm an otolaryngologist). I'm surely not going to publish my research online to WebMD first... So when Hambini comes on here and gets pounded on by a couple of people who, in their defense, are trying to act like a peer-review process, I can see that it would get old quickly trying to defend some work in a forum that is not a legitimate source of peer review. It then begs the question, why did Hambini do the work and post here at all? It seems he was curious and wanted some answers for himself and was willing to share the data. There were words to that effect previously. Perhaps some alterior motive will be exposed on GCN, haha.

Basically, what I'm getting at is that tanhalt and WMW, you've made your points, you don't feel that hambini is transparent enough, throwing the data and results in to question. From your point of view, can't say I blame you. Hambini, you feel that these people are not your "peers" and therefore not able to offer meaningful critique. From your point of view, can't say I blame you.

Great, that is settled. Moving on....

IMO most of it is fair.. the original post literally only had the result graph. It was only through all this back and forth did we get the blog post to its current state which gives way more context. Seems they were excited about doing some "proper" wind tunnel testing that no one in the bike industry can do (or even has access to), yet didn't expect people to ask them to explain the reasoning behind their methods nor wanted to have the responsibility to explain it at all. Once they got the notion that some of the posters are affiliated with some of these wheel companies with they just completely shut down. I bet the reality is that at best some of these guys on here or slowtwitch are either wheel resellers or someone who wants to defend their purchase (FLOs) with some sort of engineering bachelors on top of that. They should just close the thread and sticky it really..

[natlife]

This thread has so much good information thanks to @Hambini

Question regarding measurements. How much does bike lean to the wind when riding crosswind? Do you have any data on this or does it even happen? I feel that strong crosswind and can see from L/R balance that I also compensate it pedaling. I think this is a something that is not measured in wind tunnel but bike is static hence difference results in real world testing.

That is a very interesting question. I'm not sure practical implications are totally relevant, but it's surely an interesting physics problem to discuss.

Since we're leaning into the wind the, the moment of drag will be equal to the moment of weight (assuming the center of rotation is equal to the center of gravity). So we can start with Drag being equal to Weight times sin of leaning angle divided by cos of leaning angle.

Next we can build a drag equation dependent on leaning angle which would be Drag equals air density divided by two, times Cd times apparent frontal area times cos of leaning angle times speed squared.

The problem we run into now is that wind tunnels do not measure CdA, they measure drag force across the direction of travel, which leads to inferred CdA that is only valid a 0 yaw. CdA ny definition is supposed to factor in A as being apparent frontal area as seen at the effective yaw angle. So CdA for leaning angle calculation purposes goes up with yaw. A can be calculated pretty easily at yaw and can be extrapolated afterwards with leaning angle, but Cd measurements for cyclists at yaw are unheard of (anyone ever mounted a bike at an angle on the platform? Most likely not because side forces are transferred to the road, so aerodynamicists ignore them. There is a RR impact though. Scrubbing RR losses on track bends have been measured at 25% and leaning into the wind would be analog to that).

The solution I come up with is then: Leaning angle equals Sin^-1·(-W±sqrt(W^2+4·(Ad/2·Cd·A·V^2)^2))/(2·(Ad/2·Cd·A·V^2)) where W is weight, Ad is air density and V is speed. Area will be the apparent frontal area as seen by the wind say 0.5m^2, and Cd as seen by the wind I'm not sure but I would peg it around 0.9 at 15 degrees yaw.

So if I had to guess, a 60kg rider at 40km/h into an apparent 15 degrees yaw would lean by around 3 degrees.

[hambini]

But then the time you spent writing answers like this could have been used to tell us what FSR means among other things.

Because Tanhalt and some others on here are not as impartial as he likes the world to think.

I haven't gained anything by providing answers, I was just trying to be helpful.

I didn't even start this topic off!

And I agree with Otoman.

[SuperNonAero]

Hey Hambini,

Two questions.
When will your gcn segment be online?
When do you expect the new wheels data you have tested and recorded, will be put online?

Cheers

[Ed72]

I own lots of FLO wheels. Hambini's yaw model opened my eyes to the possibility that other wheels could be faster.

After Field tests (Chung) and a few weeks of road tests (back to back ABBA type segments), I am glad to have my new front wheel and in fact, the wattage difference (improvement) that I measure at 30 km/h and 50 km/h is actually a little higher in gusty crosswinds than Hambini's results would have had me anticipate but about equal expectations in normal or zero yaw conditions, such as field testing.

So. Thank you again, Mr. Hambini, it is such a pleasure to go faster.....with less power.....for this old guy.

FSR (Free Spectral Range)....I think......

https://etda.libraries.psu.edu/files/fi ... ions/10351

[silvalis]

More wheels are being tested. I will update the original post with results.

Was there another update with additional wheels? (I can't keep track)

[tanhalt]

Hey Hambini,

Two questions.
When will your gcn segment be online?
When do you expect the new wheels data you have tested and recorded, will be put online?

Cheers

Speaking of GCN, one more to add...how do you square your proclamations of impartiality with the fact that GCN is apparently known (I've heard this from a bike industry journalist) as a "pay to play"-type review site?

[GlacialPace]

After Field tests (Chung) and a few weeks of road tests (back to back ABBA type segments), I am glad to have my new front wheel and in fact, the wattage difference (improvement) that I measure at 30 km/h and 50 km/h is actually a little higher in gusty crosswinds than Hambini's results would have had me anticipate but about equal expectations in normal or zero yaw conditions, such as field testing.

It may be earlier in the thread, if it is I apologise for asking again, but what did you have and what did you replace it with please?

[kgt]

It's not a bad thing that people (in general, not just specific members) question Hambini and ask him about his protocols, methods and data. That's welcomed, even if it becomes frustrating when he answers but they react as he never did.
It's laughable though that the same people never questioned tests from an online blog, a cycling magazine, the 'Chung method', or a big manufacturer although these are full of missing data, simplistic methods and lacking protocols. They are instantly persuaded for some reason.

[mattr]

It's laughable though that the same people never questioned tests from an online blog, a cycling magazine, the 'Chung method', or a big manufacturer although these are full of missing data, simplistic methods and lacking protocols. They are instantly persuaded for some reason.

Persuaded or paid?

[Bassett]

Hey Hambini,

Two questions.
When will your gcn segment be online?
When do you expect the new wheels data you have tested and recorded, will be put online?

Cheers

Speaking of GCN, one more to add...how do you square your proclamations of impartiality with the fact that GCN is apparently known (I've heard this from a bike industry journalist) as a "pay to play"-type review site?

I think most of us are a bit bored of this type of remark /reply

[moonoi]

Hey Hambini,

Two questions.
When will your gcn segment be online?
When do you expect the new wheels data you have tested and recorded, will be put online?

Cheers

Speaking of GCN, one more to add...how do you square your proclamations of impartiality with the fact that GCN is apparently known (I've heard this from a bike industry journalist) as a "pay to play"-type review site?

All of their paid/sponsored content is highlighted as such in the videos, no different from BikeRadar or CyclingTips in this respect. Just because some content is paid for doesn't mean all of it is.

I don't see how your comment is valid or relevant in this context.