Shame I can't give this video 100 likes.

Just wondering, was the bird translating everything you said into bird-speak as well, for all those avian cyclists out there?

I’m have reasonably set up dura ace c50’s they are quite old but well maintained. They cost me for the set not a lot of money second hand. When I roll down a hill with other people I’m always faster than them. I’m not saying it’s the wheels... Most the riding buddies are using $12,000+ carbon top of the line carbon aero bikes. I’m on a alloy 7.2kg bike with a decent spec that set me back at most 1/4 of the cost. I’m of average hight and build. A lot of the them are smaller and focus on racing much more than I do. I’m still in the top 5 of most regional crit races I enter. There are so many factors in cycling narrowing it down is very hard. But taking each aspect you can change easily (spokes eg) and just making them slightly better will have a huge impact eventually.

Back in the late 80s early 90s I had two wheel sets. The only difference between them was the hubs. everything else was the same, tires and all. One set was ultegra, the other was dura ace. With the same fitness, the dura ace set was 1 to 1.5 miles per hour faster.

you should try balancing the wheels to find out if there's any difference in results.

Great topic which is never discussed.I have 35mm Bora Ultras,which because not too deep should not be too fast,They are ridiculously fast for a shallow wheel.What gives...The whole package I feel is what is rarely mentioned.Hubs build quality ...Spoke count etc.

Bear in mind: On a travelling wheel on the road the spoke closest to the road is doing zero kph! Whilst top spoke is doing 2x bike speed- Based on unlinear aero drag this fact may produce a different result compared to a static wheel spinning rig.

I am 66 years old cyclist, riding almost entire life...not professionally, but prity hard anyway. I like this guy bringing up the issue of aero drag up, but there is really much more to it. I will just mention the basic concerns: Bearings and its lubrication oil type, size of hub, profile and weight of spokes, nipple material, weather the nipples stick out of the rim or are hidden, nipples can be on hub side, weather the spokes are round, oval, flat or drop shaped, how well the spokes are aligned to the direction of rotation to minimize drag, if the spokes are shaped /flattened all the way to the wheel or the nipple vs. there is (as on majority commercial ones) are with round shape left, how big is that area, depth of the rim, shape of the rim, weight and shape of the rim, tire weight, tire shape, tire and rim thickness miss match. Also, I am wondering, if anyone thought of using avian(bird) feather lubricant on the outside of the wheels, frame, the body and apparel....because , obviously the feathers create a drag, but the birds lower it by putting their specific lubricant(just like fish does) to lower the drag. And then, there is of course the helmet and shoes. It is obvious, that elimination of any wind drag is of big help at higher speeds, which can be seen on the bikes with wind shields or even recumbents or totally encapsulated bikes, as in following example : bike at 133.78km/h = 83.35mph. phys.org/news/2013-09-high-tech-bike-world.html

If this aerodynamics thing keeps going, it'll end up like Formula 1 and they'll have to implement DRS and KERS to facilitate overtaking...

Genius & we'll said! I had been wondering why people weren't talking more about the length of spokes & the associated drag at higher speed...like fan blades....

Interesting points you make. You're right, most of these manufacturers do not even bring up the topic of rotational drag.

For starters, you're talking about aero wheels whilst spinning a Lightweight Meilenstein. My understanding is that Meilensteins were designed to be LIGHT rather than AERO. And that the depth and the "V" profile of the rims are that way to match the angle of the carbon fiber spokes which are bonded to the sides of the rims, not for any aero drag reduction. The spokes run from the rim, across the hub flange, and back to the same side of the rim, further around the circle. I suspect that the "V" cross section of the rims is more draggy, perhaps for airflow at the leading side of the wheel as well as for airflow at the trailing side of the wheel. I have used a set of the 16/20 Meilenstein clincher wheels extensively. At 1196g without skewers (calibrated scale) mine are certainly light, perhaps 200-300g lighter than most other clincher wheels. Subjectively they feel very smooth. Quite susceptible to crosswinds and eddies, and braking performance in rain is abysmal (though I lack experience with other carbon rims). The brake pads supplied with them work fine in the dry. Nice wheels, but so spendy I probably would not buy them if I had it to do over.

Also important in real world: tire overhang will reduce the aero benefits of your wheels drastically... And rolling resistance on rough tarmac is much lower with wider rims and lower pressure. A 25mm tire on a 21C rim can easily be run at 60psi if you are not too heavy - 70psi will even be enough for "stallions". And last but not least a wider fork also offers some drag reduction.

Like Marcus Bondeo commented " What about Wheel Balance ". I just don't get it!!! Tech guys talk blue in the head about bicycle wheel Aerodynamics, and never say a word about the most obvious problem on a wheel that's going to spin at high speed, and that's rotational wheel balance!!! There is no way to get any type of accurate wheel performance data on aerodynamics of any other test difference until the wheel is balanced perfectly making it a steady test platform first. Unbalanced test wheels will give erratic and unreliable test results. Like they say "If you're going to do a comparison test, you need to level the playing field first".

It doesn't make a lot of difference anyway - just buy a cheap Shimano wheelset and save your money for something worthwhile. I got a pair of expensive Ultegra 6800 wheels recently ( with no noticeable improvement in performance ) and within a week a spoke snapped ( £8 to replace). Reminds me of the outroar when a cycling journalist put the spanner in the works by describing the humble Triban 3 (£200) as better than fancy bikes 5 times the price.Up against the laws of diminishing returns. Vast sums of money for tiny improvement.

I am a physicist. There isn't much physics in this, it's quite hand wavy. To theoretically describe what's going on you need to draw force diagrams for what the wheel is doing when the bike is moving. For example, a wheel isn't moving at all relative to the ground or the air at the bottom where it is contacting the floor. At the top it is moving at double the speed of the bike relative to the floor and air - so a 25mph rider's wheel is moving at 50mph over the floor at the top of the wheel. Couple this with wind power generated by the wheel (commonly termed drag) is proportional to V^3 (speed cubed), not exponential as quoted (most wrongly used word ever by non-engineers - it has a specific mathematical meaning which isn't "lots") and you can start to calculate wind resistances (with suitable assumptions). However, what I thought this would be about, which really is relevant is rotational inertia, which is higher for these heavier wheels - important for accelerating in a sprint or to accelerate onto the back of a pack if you're getting suddenly dropped by a jolt in the peleton. The term "rotational drag" isn't physics - a bit like di-lithium crystals didn't power Apollo 11 to the moon!

Great video - this is why a wheel like the Ksyrium R-SYS is so poor aerodynamically; the spokes are huge.

it amazes me how manufactures say how they have put so much time into research and development into aero dynamics when the two biggest thing about wheel rim aerodynamics is the depth and how blunt or sharp the leading edge is, yet they have only just been releasing wheels that have blunt leading edges that vastly reduce how much the wheels get affected by cross winds!

I built me a 29+ bike, using carbon wheels and WTB 3.0 tires. When I am riding and looking down at that front wheel, I can't help but think at how that fat tire is deflecting wind from the churning spokes. Yes, it has a fatter profile, but as you are saying that is not the entire story. I did a test and found this bike I built was just as fast as my Trek Superfly 29er. I raced the bike in a gravel race and found it to keep up very well. It was actually very fast on the descents as those fat tires gripped much better on the twisty dirt roads. It didn't seem to do as well on the section of road as the true blue gravel bikes, but if there is a course with dirt road climbing/descents with a smaller portion of paved sections the 29+ seems to be a good way to go. I built my bike with almost all carbon fiber parts, no suspension to make it light and fast. Gearing is a 1x11 with a 36T Wolf Tooth front and a 11x46 in the back.

The aero and weight aspect of cycling has us trapped in an exponential marketing rip off. We all want to get better or faster, but some people are paying thousands and thousands to remove those few grams and/or drag. And as I always say, unless you're making a living racing bikes, spending this kind of money is crazy and obsessive. Don't get me wrong: I love technology; is the pricing that has gone mad. Cheers and good video.

Interesting consequence is that since the speed of an individual section of the spoke increases linearly from the hub and that the drag is proportional to V^4 then in terms of rotational drag it's the spoke nipples and only a small section of the spoke that matters. Or, to put it another way, the rim depth actually matters a great deal.

Thank You for the video. Couple of nagging questions here: So right now we talking about rotational drag, a part of overall aero drag, right? IS a rotational drag a factor that can change with yaw angle? If so, how we would account for that? Deeper rim is faster for the reason you pointed out, but how about the width? Strictly speaking of aerodynamics, narrower rim and tyre combo should be faster? Marketing is pushing road bikes in the area of 25-27 mm rims, using argumentation of wider tyres and lower rolling resistance. But, as you said, rolling resistance grows linearly with speed, whenever aero drag is exponential function and wider will be slower ad high speeds. So, actual question is, where is a sweetspot of comfort and speed?

I find that to get the maximum reduction in drag from my wheels is to completely remove them at the start of the ride..... :-)

I you're not an elite level cyclist and want to see immediate improvements just wear tighter fitting lycra and perhaps improve your diet, sleep and position on bike. Spending big on wheels is pretty pointless for most people.

I was looking at some Rolf Prima Vigors. Any good?

This is also why Rolf (and the first Campy Shamals) came up with very low spoke count (only 10 in the front in some cases). The engineers know. They're not running public universities with duties to publish all results.

Southampton Uni did some aero tests for rotational drag 9 years ago measuring watts used as well as rider position including the 'Obree' (which was significantly quicker for same watts even compared to modern 'tri'), the paper is free to view. The wheels they made up included 6/12/18/24/36 spoke plus trispoke/disc wheels. Rotational drag is something I'd always gauged wheels by in terms of how slippery they would be, for anyone without kit that the manufacturers have (pretty much everyone) isn't it the only real test you can do (attachingas well as roll down tests that you did though even that can have its pitfalls due to even small changes in wind/body shape affecting the test. You also have differences in rotional drag due to the shape/width of the rim and the tyre size being used, choosing to go with a wider tyre for the benefits they bring on a narrower rim can play havoc with the airflow. Personally I run wider rear as the negative effect on rotational drag due to a wider tyre is less pronounced than on the front, that and you have more bodyweight on the rear wheel in any case. (27/25mm tubs for me as I'm an ex rugby forward) All that said, what Corima rims/wheels were you using and what Lightweight wheels did you compare it to, I realise you were making a point re round/aero spokes and indeed spoke length (20" wheels being 'slipperyist) but from what you were saying you weren't comparing like with like. (I like corima btw, some of the best braking rims in the wet IMHO)

Great video. I have a buddy that has a set of Zipp 808 and he made a comment that u need some strong leg to turn them.

Thoughts on DT Swiss ARC 1400’s? What’s the ideal rim depth for all round riding?

This does not apply to 99.99% of riders. Don’t over think it guys, just get out there and ride, if you want to get faster, ride more and lose weight!

Great info, but what would be the ideal spoke and hub combination?

GOOD video again. I might just point out though that bearing drag or frictional moments are not always linear. It can be much higher at very low speeds while lubricants are in a somewhat transient state, and much lower friction​ at extreme speeds. But in bike speeds a linear assumption is good enough ;) Ps is the pool green by design? if not I'd happily be the pool boy in exchange for a dip!

I think you are right-on but at the end of the day, unless I'm a pro rider trying to shave milliseconds out of a time trial, it just does not matter.

Aero drag of wheels is an extremely complex problem. A central issue is that wind tunnel testing deals with steady state measurements, and real world airflow is far more complex than that. Even with steady state laminar airflow hitting the wheel, the leading portion of the wheel does not experience simply the opposite airflow from the trailing side of the rim; the spokes and the leading portion (and their motion) disturb the airflow. It's worth stepping back and asking what benefits reduction in aero drag might yield overall? And how much additional weight (aero usually entails adding material somewhere) can be tolerated to gain this improvement? Aero can certainly help in situations where one is exposed to the air (TT, solo breakaways, in a small break or team TT, and just training/recreational riding alone). The benefit depends on speed through the air and whether the air is undisturbed. Riding more slowly (weaker rider or going uphill), in tailwinds, or in blustery conditions all mean less benefit. So many people seem oblivious that aero is unlikely to be helpful when one is drafting or riding in a group (e.g. peloton), already benefitting 20-30% from the bubble of air moving with the group. Additional weight, particularly in wheel rims, costs dynamically whenever one must accelerate (as one does constantly when adjusting speed in a group and also when tagging back onto the pace line after a stint at the front). Aero can also added weight to carry uphill. In simple terms, aero helps you in some situations whereas added weight is a minus virtually all of the time.

Interesting video. I guess it come down in wind tunnel testing methodology and how they calculate to overall co efficient of drag. If they spin the wheel up to say 30kph then take a reading off the instrumentation for drag, or do they spin the wheel up to a specified energy, or spin the wheel up to again say 30kph monitor the power required to do so and add that to the overall drag.

Is it true to say that the top of the wheel is moving forward at twice the speed of the bike? That would increase the effect of the rotational drag on the spokes at the top of the wheel even further, especially considering the cube law. Interesting video, cheers.

Great point. And three years later, a few nerdy comments and questions. All published data, or marketing faff will talk about solo riding. In practice, unless you're doing tt or tri, nearly all competitive riding for nearly all riders will be in a group, large or small (how many all day solo breakaways succeed anyway?). Wouldn't that mean the 25% spoke contribution increases pretty drastically? Wouldn't a group drag the air with it, chopping it to utter turbulent chaos, and make any prediction something of a guess? And what could cause any significant difference? I guess spoke count, lacing pattern, and flange with could play a role. But then again, most high end wheels out there will be built with DT Aerolight or Sapim CX-ray, and they ar very similar at 1.2x2.3 (Sapims have a slightly longer bladed section/shorter round section at the j-bend and spoke thread end, by eye, and could possibly be slightly better). The hub flange diameter and with also greatly affects lateral stiffness, and I would not want to make any sacrifice here for a marginal aero gain. Internal nipples probably will make a discernible difference. But on the other hand it will make it an absolute pain to true a wheel or replace a spoke, because you'll have to remove the tire, tube or sealant, and rim strip/tape, or even worse a tubular tire. Not sure about that either, unless you're a pro team with a generous budget and spare wheels sticking out from everywhere.

stockman1963 1 second ago Love your wide range of topics. Long while back you did a video on tire aero drag, You had said that much of the data presented was with the tire fixed in a wind tunnel not rotating. I thought of a way you could do a comparison with a couple for tires. It would be representative comparison. You would need a very high speed fan, high speed drill or something to get wheels going around fast, RPM reading so you start at same speed each time. you could do reading - Time wheels spin down time without fan blowing on them and then with fan blowing on them. Then compare time different. That would be representative of a difference. Maybe do 4 runs. A -- no fan coast down to zero or some rpm you pick. B-- Coast down with fan on . Then repeat again each. High speed Fan -- Lasko 20" High Velocity QuickMount, Black-Easily Converts from a Floor Wall Fan, 7 x 22 x 22 inches, 2264QM Can e-mail me for ideas I am an aerospace engineer too.

Interesting..i have not heard of this subject, it would be very tough to test as wind changes on each test run, but im going to look for your other test on it, nice vid!

I'm a recreational fitness rider. Whether I arrive home 30 seconds earlier or 30 mins later makes no difference to me.

If they measured the power it takes to spin the wheel without these rotational drag in the equation and the power is better than the other wheels, does it really matter since the same measurement was done with the other wheels? If one wheel have a better design spokes that cut the wind better than the other, can we not assumed that this wheels will have a better rotational drag?

Rotational drag has minimal impact compared to the benefits gained by the benefits of aero design....hence the reason you see more pro's running deeper section wheels. the amount of time that's spent getting the wheel up to speed is very small compared to the time spent spinning!

Just wondering: When building my own wheels - choosing a 101 or 202 type of profile, but choosing the BROADEST spokes out there, and having a LOT of them, could possibly boost the aero considerably, for a quite nice price?

I'm confused, so would a deeper section rim generally have less rotational drag, or more?

Are the big companies really not aware of this? This is such a basic test and really would not be expensive in the context of wheel development. Is it just that it's not something that changes much between designs?

Keep in mind, the spokes live in a highly disturbed airflow environment, being in the wake of the tire/rim. In essence, the spokes are drafting the tire, this reduces the drag effect on them.

Thank you very much.

Do you have any tips to precisely set spoke direction for aerodynamics? It's something that always bugs me when I tune wheels.

I find these sorts of videos really interesting , as much as I like GCN they have a lot of "bias" videos where big companies pay them to show off the products. However, you show products and try to prove why they are like that .

Very true for drag and not true for similarities.wheels are close but neither similar nor the same. Recently Zipps turned out 2 kmh/hr slower than ENVE SES and Aeolus, 35-55 km/hr. Zipps keep turning into the wind and are very twitchy be it light... chief reason is the enves having better angular momentum and gyroscopic inertia... bontrager Aeolus gave me another .5 on the enves. over thousands of kms these nuances are clear. but wheels are not similar as even 1 mm here or there is huge in aerospace applications.. ENVE issue is wheneve they use Chris Kings those can start dragging with 5000 kms. DT Swiss is better obviously. Zipps are overpriced garbage..

Isn't the top of the tyre moving forward at twice indicated speed the biggest problem from an aerodynamic perspective?

Maybe why dura ace c24 wheels are SO good and FAST 😉 ( with latex tubes and Michelin Power competition tyres )

A basic calculation shows that rotational drag is 1/3 of the translational. So the 25% figure you quote is right on.

Very detailed video.

the rotational drag will mostly be down to the bearings and the weight of the rim. You can have an extremely light rim which spins forever with little power and it will not be as fast as the other more aero rims.

I got a wheel set with dt swiss 180 front and 240 rear on some bontrager rsl1 51's once those wheels start going they just don't wanna stop.

Well when I looked up some aero wheels I could read about rotational drag

tire - air friction is also a huge factor. Especially since the air is hitting the tire straight on.

Good info! Need a mic. Tho

At last. Give me a great hub over a shitty rim any day

Thanks for raising awareness, but did it need over 7mins to get that 1 point across?

I'm a new subscriber. I like this video content from mechanical engineering standpoint. could you recommend any most bang for your buck aero wheels?...when I got into time trial racing circa 2013 I purchased sram S-60 wheelset, which has hidden nipples and bladed spokes. also they had just acquired zipp, but we're much better in pricing, with similar "toroidial" rim shape. but of course I don't have a rotational resistance guage or wind tunnel to back up the claims...just my own personal data and tt results year to year (which varies on weather conditions). anyway, kudos on good info video. from Hawaii

This is why I run tri spoke front wheel for my tt bike on race day

well said, good video! Btw that may be the reason (or at least one reason...) that the Lightweight wheels in real world tests give similar results to those modern shape aero wheels though they are using an "old" V-shape profile - what should be less aerodynamic... A small (but not unimportant) remark: 5'27" is not correct. the air resistance increases square to the speed, the bearing friction is CONSTANT (in the strict sense it decreases a bit with increased speed - but thats negligible); so the POWER to overcome air resistance is cubic (square resistance x speed difference) while the POWER to overcome bearing friction increases only equal to the speed (constant x speed difference)

LW Meilenstein that essentiel is LW "standard" is NOT a aerowheel and has never been sold as that, not from LW or Carbonsports that is. The only thing mentioned aero is the lens shaped spokes. The shape and high of the rim was do to limited production possibilities back in '95 when Dierl/Obermayer made the first wheels in the small garage near Munich. They actually wanted to make the wheels like the Ventoux model that came later in 2001/2002, but back then in '95 were not able to do so. The high of the rim is simply the space between the spokes, when you draw a line from outside the hub in one side, to the edge of the rim in the other side - which actually is the path of the spokes.

Cant see the point of those half way house, heavy wheels. A lightweight road wheel with a monokote covering (which is used for covering rc planes and weighs only a few grams, and is easy to apply)would perform much better than a deep rim wheel or even a proper carbon disc wheel. Theres a vid on youtube of someone applying monokote to wheels and they look awesome. You get the full aero benfits but retain the lightness

How do you conduct an aerodynamic test of a wheel without including rotational drag?

I hold a number of downhill Strava KOM's. I set out to crush a record held by a 24 yo Club champ when I was 47 over a technical 12.4km descent. I still hold that record after more than 2 years. This record (and others) was achieved on a pair of 8 year old Mavic R-SYS wheels. Worrying about the drag on your wheels is a very low order issue in the "drag" discussion. The biggest drag is you and your clothes. The bike is probably only 20%: if that. There are many issues with wheels and if you are racing or descending braking is right up there. Carbon wheels will not stop you anywhere as well as alloy wheels from 85km/h to then turn a corner. So if your "race" has the need to slow down, then the later and harder you can brake the faster your overall time will be... and so it goes. Helmet, clothes, shoe covers, elbow position, power when in the tuck, tyre pressure and choice, etc, etc. I'm still using those wheels. They are fast, reliable, cheap and durable. Carbon wheels are over hyped and over priced IMHO. Judging from your test vid outfit you would gain real speed by: buying shoe covers, wearing a long sleeve aero jersey without rear pockets, buying a truly aero helmet, take off the gloves, put your hands and elbows in next to the head stem, put on a second drink bottle, lower the position of your shifters, and lower your stack height.

Rotational drag is the force that stops the wheel from spinning. The larger this force, the more power you need to keep it spinning at a constant rotational speed. Just to explain it physically correct ;)

The reason that they don't do this is because they make the rim technology. They buy the hub components and slap a name on them. The spokes are all what you can do. Their main concern is the rim. If you care about rotational drag then you should buy hubs and new spokes and pay a wheelbuilder to build them up. To measure rotational drag differentiation you need to test all the different hubs with different bearings.

What about aero in crosswinds? does more aero mean more of a negative effect?

Great review-nice back yard.

Its so good , if somebody clever find a time to film a video like this with pure purpose to inform and share their opinion with public, thank you so much. I will definitely focus more on spokes as on expensive aero wheels :-)

My aero 65 hold water from light rain days. Should have bought China knockoffs? I’ll just drill a hole and be a troll.

good insight

Bearing drag is not proportional to speed and the drag is not exponential either. But the idear is correct that Drag increases faster.

great video! i think wheels are very much about marginal gains and you definitely make it clear in this video. i also think dt swiss knows what they're talking about since they're such a prominent manufacturer for wheels. i definitely trust their engineering the most - 240s hubs are king in my opinion (180 for the rich guys) and you bring up a great point in this video. i do get offput by the fact that shoe covers and helmet covers/aero helmets provide the same aero gains for so much less but it's also nice riding bling wheels too.

Hambini age 5 mention = automatic subscribe. now go on fellas, show these wankers

Loads of real world testing has been done on the advantages of aero wheels. IE a rider does a certain amount of watts around an open air track with different wheels on each time. The difference is pretty big.

where can I get that t shirt?

If considerable rotational drag is produced by the revolving spokes,perhaps large flange hubs(favoured in the 60's) could be making a comeback,this would reduce spoke length also producing potential a more solid wheel?

So, we need aero spokes.... On a bike travelling at 40kph, the spoke tips will be travelling at speed of about 70kph (top surface of the tyre will be travelling at 80kph) at the top of the stroke and zero at the bottom. Where can I buy affordable aero spokes and how much are they? And I don't mean flat spokes..

lol "Bear in drag"

the wheel isnt balanced if it not stay in the position you leave it. the roll force is elliptical. it takes away momentum. so a counter weight is needed. to account for the air valve.

thank you

Next time, do the video without the birds.

Good video and sound engineering logic. Thumbs up to DT Swiss for being a bit more honest than rival wheel makers.

So, what are you trying to tell us??

For me, what is missing in these discussions is a breakdown of the TOTAL energy losses of a moving bicycle, so that we can get some grasp of how large each component is. Sure rotational losses may be 25% of the total WHEEL drag, but is that 25% of a tiny or large component? I would GUESS that the drag of the rider's body would be the largest component? Another factor is speed: energy losses due to aero drag go roughly as the square of the speed, so a lot depends on what speeds we are considering. Mechanical frictional losses probably have some other relationship to speed? And rotational inertia in a wheel? I suspect that we are constantly accelerating and decelerating slightly as we ride even on flat terrain, so that rim+tire weights might factor in even when attacks and sprints are not involved. I would love to see data on this.

I like momentum :-)

Totally flawed and inaccurate assumptions regarding the impact of bearing resistance imho. Run both wheels with the exact same bearings and then review the rotational drag.

All you said for nearly 8 minutes was"this is a problem...I think." You offered nothing in the way of solution or really explanation. Are you saying that we should ignore the impact on the 75% translational drag just because "they" aren't telling us what the rotational drag is? Maybe you are saying something else and I missed the point altogether. All I know is when I ride my bike with my aero wheels I go faster than when I ride my bike without the aero wheels.

There is no rotational drag. There is energy required to spin up a wheel. But once it’s spinning there are no watts required to keep it going other than aero drag And drag from friction.

Your wheel in the stand is out of balance. This is very obvious as the valve is always rotating towards the lowest point... Interesting vid BTW.

sounds like a happy bird in the yard

Once again.....wheels tested on rollers...in a wind tunnel is not accurate. The tires touching the ground is not moving.....no one takes this into account when discussing this.....

This guy sounds like Ant Middleton in terms of his accent-haha!

Is this truly a neglected issue? Does their testing REALLY not test this? Because if they are using rotating wheels in a wind tunnel... they are testing this. I would assume that if there is a rider on rollers in a wind tunnel, the net effect is all that matters to the rider anyway... not where the inefficiencies come from. What I mean by this is: The rider won't notice the difference between rotational drag and translational drag. So if Zipp for example is saying that their wheel is 5 Watts better than X brand, under the same testing conditions in a dynamic cycling environment.... It doesn't really matter. If they are using overall drag in their design criteria, and the overall product testing takes this into account... who cares? That being said... if they aren't testing this. It is bull.

Thank you, I‘m now 0,00001% faster 😂

good thing people like you and Hambini contribute to better understanding amongst people about those things. The bicycle market and all it's marketing nonsense is mad #justfinishedmydegreeinmechanicalengineeringtoday #worldslongesthashtag :D :D