Aero Wheels - What they are NOT telling you!

[@Hambini]

Shame I can't give this video 100 likes.

[@CyclespeedTours]

Aawwwh, that's nice!

[@loopie007]

Actually I feel different. Lots of questions and concerns, but no possible solutions to a potential issue. No testing, no measurements, it all seemed like rumors and complaining. I understand the issues being raised, but people look for solutions, not more questions. Sorry CT, just my view.

[@CyclespeedTours]

I'm simply raising awareness of a long neglected issue, and pointing out that DT Swiss have invested time and money into optimising their wheels in this area. I don't have the testing resources that DT Swiss have, so I can't compete in that area. The 'solution' is to choose a wheelset that has been wind tested for ALL aspects of drag and that has been optimised for it's spin performance (amongst other things). And also to show that some of the big wheel maker's data is very much cherry picked to show you what they want you to see, but I guess we already knew that.....

[@mr.actiongal1017]

you actually can

[@VelotvUK]

Cyclespeed Tours enve is said en-vee as such ✅

[@balazra]

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.

[@CyclespeedTours]

DA C50's are great wheels and fantastic value. No point on getting hung up on the very latest shapes and designs, there isn't so much difference between 50mm wheels. And nothing better than to beat a 12k bike rider on an older heavier bike!

[@werdsmyth]

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

[@jbirdperez6003]

the bird just threw it self to the cats... zzzzzzz

[@sonofsun4]

Indeed, the bird has translated everything to "tweet" and then posted it all on Twitter....I suppose :-)

[@MarcAntoine01]

More like the guy translating the bird since I can hear the birds more

[@aldrinclementina4297]

lol

[@jmaxson150]

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.

[@lomilomi3535]

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.

[@CyclespeedTours]

Absolutely

[@beinnnabhfadhla6457]

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.

[@CyclespeedTours]

Sure, very similar situation in many different things like cars, skis, boats, etc. You have to invest a lot more money to get smaller and smaller improvements. That's life. Whether it's worth it or not depends on your disposable income and your skill level in the given sport. If you're trying to get a podium place, even just in your local county, then it could be worth while.

[@dansotelo228]

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".

[@CyclespeedTours]

Agree it's an important aspect to consider, although I'm not sure it really affects aero results that much though. My new Caden wheels (see my most recent video) come with a 'bullet' balancer in them from the factory.

[@beaver7847]

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.

[@CyclespeedTours]

Thanks Beaver, all good points - have you seen my silicone infill video? Helps smooth the tyre/rim transition. Re. Tyres and pressure, I find it depends very much on your road surface. We are fortunate in Brittany and Majorca to have very smooth roads, so I can get away with slightly thinner and higher pressures.

[@karltube99]

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.

[@CyclespeedTours]

Yes, very true. A static test is far from perfect, but can hopefully give some kind of pointer as to real world performance.

[@jiritichy6855]

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

[@RealtorJoeVioli]

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....

[@CyclespeedTours]

Exactly! The tip speed is very high.

[@VegasCyclingFreak]

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

[@CyclespeedTours]

Thanks - maybe they are doing some kind of testing, but they aren't releasing results....

[@VegasCyclingFreak]

They seem to be more concerned in how the wheel deals with crosswinds, yaw angles and hubs than about rotational drag. Maybe they believe the other issues outweigh rotational drag?

[@CyclespeedTours]

Maybe, but DT Swiss seem to think it makes up 25% of the total, which may be debatable, but it's nonetheless significant.

[@VegasCyclingFreak]

Yes, 25% is enough to consider. I'm with you on that.

[@Gizmoimages]

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.

[@paulflory3532]

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.

[@CyclespeedTours]

It's just by chance that I have a LW wheel in the stand - I'm not claiming any special performance for that wheel. You are right about the wheel's construction, but the difference between a V shape and a U shape is not massive and is mainly felt in crosswinds. I personally never had any issues with the LWs in crosswinds. Having a deeper rim reduces spoke air attack which is valid for any deep wheel. Yes, nice wheels, but I recently sold mine for some Campa Boras, much cheaper and not much difference in performance.

[@TheMadman457]

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

[@chrisjames1924]

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.

[@CyclespeedTours]

I would tend to agree; there are far easier gains to be had elsewhere. But if you want to sniff out every little gain, then these are valid ones.

[@garybowles8340]

Chris James I’m not a great cyclist, but bought the Giant Propel Advanced Disc this year, looks awesome, and that’s why I got it! Agree entirely with your post, but when the bike looks good, it makes me feel good 🚴🏽👍🏼😁

[@frankekeler7682]

There are other advantages besides aero with carbon wheels.

[@dickieblench5001]

​@@frankekeler7682 My dura ace tubular 50s sound pretty cool to be fair 😂

[@sarahfenton9132]

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!

[@CyclespeedTours]

Firstly, I think most people that have looked into this area are quite quickly aware that velocity relative to the air at 180' is zero and 2v at the top (0'). Secondly, Cambridge dictionary's definition of exponential in a mathematical sense is; specialized mathematics containing an exponent (= a number or sign that shows how many times another number is to be multiplied by itself): 6^4 is an exponential expression. Thus V^3 is also an exponential expression. But in any case the more 'general' use of the word, simply describes a rapid increase. Cambridge again; An exponential rate of increase becomes quicker and quicker as the thing that increases becomes larger. Heavier wheels? Seriously? They weigh 1150g a pair and are thus some of the lightest around. And it has been shown mathematically many times that rotational inertia actually only plays a very small part in a wheel's performance. I see no problem with 'rotational drag' used to convey the drag created due to spokes spinning and to differentiate from the drag created from a wheel moving linearly. Surely we can agree that the overall drag would not be the same between a non-spinning wheel moving forward at 40km/h and a wheel that is spinning.

[@WheezyCyclist]

Love this reply ....was going to say rotational inertia has a much larger effect on the wheels spin than "rotational drag"

[@dickieblench5001]

No one went to the moon pal😂

[@Metal-Possum]

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...

[@BaxterRoss]

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

[@CyclespeedTours]

Exactly

[@giutubospatubo1546]

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.

[@CyclespeedTours]

Very true - some of the prices have become ridiculous lately. I did make a vid a while back looking at cost effective (i.e. cheap!) ways to get aero - shoe covers are one of the best bangs for the buck, but again, if you're not racing, not a huge point really.....

[@alannkevin]

Giutubo Spatubo omg, I was just thinking that. The other day I went to my LBS, and they were up my butt trying to sell me a set of mavic carbon and reynolds. I told them that I was happy with my bike, and they were like "no you need at least di2, once you try electric you won't go back to mechanical" ... I get it, ok technology, like you said and trust me it's very tentative, but the price dude it's RIDICULOUS, I am not going to spend hundreds of dollars just to make "an impression", I am not a pro, I only ride once a week and what I have its enough for me. Say I buy di2 and the set of wheels... then after 6 months my bike suddenly it's outdated ... like that Sworks venge, the price point was $10000, 6 months later you can get it on ebay for half that price, because the "new tarmac" is comming ... if you have the money go ahead but not me ☺

[@CyclespeedTours]

Buying 2nd hand is a great way to go - as you say, 1/2 price in 6 months.

[@marcokalle2452]

you don't have to buy that expensive stuff, and you don't have to judge people who want to buy that expensive stuff... ride whatever you want/like, as long as you just ride your bike, am I right, or am I right?

[@alannkevin]

Marco Kalle yes you are right, but we are not judging anybody like I said if you have the money go ahead, in fact for some people that's like a hobby, and it looks cool, but for me I don't like when LBS and media tells you that you "need" this things when you don't (if you don't race). 😎

[@awildtomappeared5925]

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!

[@CyclespeedTours]

I think 'vastly' may be overstating it a bit! A 50mm+ rim is always going to move around a bit in strong crosswinds. I could never tell much difference between my Lightweights, Corimas or Campas, all about 50mm, but with different leading edges.

[@MrJofArnold]

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.

[@CyclespeedTours]

Yes, (but it's V*2 surely). Absolutely, the farthest points from the hub are the most significant, so nipples are important as is the last 10-20% of the spoke. Interestingly, often, any 'blading' finishes about here, to go round again for the nipple - would be nice if it could be kept bladed all the way into the rim, and the nipple hidden inside.

[@apexdrift1]

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

[@CyclespeedTours]

Basically, you are looking for bladed spokes, as short as possible and as few as possible. Smooth hub with good spoke integration, same goes for the rim. I think we may start to see better spoke design, not just bladed but elliptical / aerofoil type shape that continues right into the rim (doesn't go circular at the worst point (at the rim)).

[@enlightenedidiot9552]

Cyclespeed Tours are bladed spokes just flattened, or are they made into a truly aero teardrop shape?

[@HeathyRoidz]

Enlightened Idiot just flattened... there is a taiwanese company that makes eliptical spokes... no tear drop... eliptical so the air can cut through it and smooth on the way out! Keep in mind that they are very prone to breaking... I seen some reviews and if you contact them they are very honest about it... if you are at 35kph and you hit a hole of decent size... it will break 1 spoke... they told me they’ve had them break 2 at a time... they are cheap 60$ for 35 or 40 spokes, I don’t remember that well... still if you break them that often... it can be pricey

[@Dhungerf60]

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.

[@CyclespeedTours]

Very true, and yet extravagant claims in all the advertising material seems to sell wheels!!

[@beinnnabhfadhla6457]

This is bleeding obvious. We are not talking about high rev engines here the wheels spin at low RPM therefore not that significant. A decent pair of tyres is more important.

[@ynotnilknarf39]

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)

[@CyclespeedTours]

Thanks for such a detailed and intelligent comment! I used Corima 47mm S+ MCC wheels (which I use in Majorca) and the Lightweights are Meilensteins. Their weight is almost identical (front wheel) and I believe the moment of inertia to be extremely close too, as the construction is very similar. It is clear that the Corima suffers due to it's spokes, even if the front's are now slightly bladed (2014+)

[@prorok21]

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?

[@CyclespeedTours]

All good questions, and I don't have all the answers!! Rotational drag would change a bit as yaw angle changes, but as long as your 'power to spin' equipment is present in the wind tunnel then you can measure for this. We can control 2 elements of drag - frontal area and Cd. So yes, wider rim/tyres are worse for A, but potentially better for Cd, but this depends very much on careful tyre/rim matching. High speed track bikes with no wind present still use narrow setups and so I would tend to think that if you are riding fast in still conditions, a narrow setup would be fastest. But if you want that extra comfort, then yes, wide is the way to go.

[@reubs91]

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!

[@CyclespeedTours]

AH, the old, aero and bike weight do not matter at all comment. Seen a few of those in my time!!

[@reubs91]

Cyclespeed Tours that only applies to the “professional” riding scene. As I said 99.99% of riders will not need to invest huge amount of cash into aero and lightweight parts, it will make no difference to their Strava times. I run a 2011 Tarmac and love overtaking people on more expensive bikes, I legit get a stiffy when I do.

[@CyclespeedTours]

@@reubs91 Well I'm really happy for you about that! ANY rider can benefit from a lighter, more aero bike. And yes, it would make a difference to their Strava times, if that's important to you. Many enjoy the tinkering and engineering aspect of improving their bikes. And you can add personal fitness on top of that. Each to their own.

[@radiocontrolled9181]

@@reubs91 But are the people you overtake actually racing you or are they just random cyclists you meet on the road while riding and who are probably on their normal leisure/training/fitness easy ride? Asking this because many times I get the impression that several cyclists I randomly meet on the road overtake me just to get their 'stiffy' by boosting their ego while thinking they are very fast. When in reality I would be going at around 60% of my maximum power. To be clear, I don't ride an expensive bike at all, so it's not he point.

[@garethjones3070]

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

[@indonesiaamerica7050]

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.

[@CyclespeedTours]

True, but if the marketing guys can seize upon a plus point, then they will let us know all about it! Low spoke counts seem less common now which is odd, cost perhaps? And of course, low spoke count is fine as long as the spokes are aero, which is not the case with some Corimas and Mavics (thick circular section).

[@indonesiaamerica7050]

@@CyclespeedTours They seize upon "plus points" that are part of Unique Value Proposition narratives. They'll tell you that they "optimize spoke configuration" but not that "lower spoke counts is always better as long as your wheel doesn't break." They sell the sizzle over selling steak because steak is commodified. The marketing stories are about selling "sizzle" or what is supposedly unique to the product that they are competing with. It's about building a "brand story" without giving away secrets or easy ability to debunk alleged "value" claims. Aside from all of that, it's complicated quantifying all these factors under real world conditions or tests that attempt to replicate real world conditions in a consistent way. I'ts not that you're wrong, it's that your conclusion is unsurprising and probably doesn't have a solution unless people want to do their own independent tests just for the sake of publishing the data.

[@indonesiaamerica7050]

@@CyclespeedTours IIRC, before big investors started paying for wind tunnels for bike wheels, all of the early tests were "roll down" tests. Cars used to do the same back in the old days. Similar to what you are doing. The wind tunnel tests don't "hide" roll down factors but simply present it differently.

[@CyclespeedTours]

All true. Wind tunnels provide a consistent testing medium in that a 40kmh wind in a tunnel is pretty much the same in all tunnels, but the real world is not so simple and the air is moving all around us all the time and is not steady. So treat tunnel test results with caution.@@indonesiaamerica7050

[@indonesiaamerica7050]

@@CyclespeedTours The only real world tests are the competitions. But those are not easy for others to use for their own equipment choices. There's no such thing as a perfect test to arrive at "the best design" or "the best system." At best you can come up with valid tests for specific theories and test under controlled conditions (to augment data taken from competitions) to help improve your prediction models. Better prediction models help design engineers and end users. But in the end, it's all about the best synthesis because you can't predict with great precision what "the best" system will be for any given "real world" competition (or training run) any more than you can predict next week's weather. For pretty much the same reasons. In summary, I'm all for appropriate skepticism and ever more varied testing on the path to creating better analytical models and therefore better ways to choose gear.

[@ceeebs01]

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

[@CyclespeedTours]

Nice wheels, but check out Campa as well. You need to have at least 45mm for any decent aero benefit, so start there!!

[@fireroadie6654]

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.

[@thomaslutro5560]

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.

[@CyclespeedTours]

Some good points there. Especially re riding in a peloton where the air is very turbulent; linear drag will reduce but rotational drag would stay about the same. I think a large hub flange diameter would actually help aero as it reduces the length of the spoke, and could even have a kind of fairing effect like deep rims do. Yes internal nipples help, but agree a pain to true. Having said that, my Boras haven't needed truing in 40 000kms and I have hit them pretty hard in potholes.

[@thomaslutro5560]

@@CyclespeedTours Me not being the expert, but here goes. My intuition says the same about flange diameter. That is, unless the j-bends and the associated round spoke sections cause trouble in this area. It actually ends up being quite wide and ragged at and beyond the spoke hole circle. Straight pull with a large diameter would probably end up making the flange it self very bulky. So very unsure all in all. Regarding the with between the flanges, I assume narrower is more aero, but at the cost of lateral stiffness. I know at least two makes of internal nipple wheels, one Norwegian, one Swedish, both small companies. Neither really tempting me for the practical issues. Boras are on my 'to get' list. Probably the only design where I'd still dare to try if they went for hidden nipples. Campagnolo and Fulcrum make rock solid wheels (basically the same wheels) The two to one lacing is pure genius, and the only way to get proper spoke tension non drive side. Low tension spokes tend to loosen, no two ways about it. I've had a pair of Shamal ultras and a pair of Zondas for seven years, even replaced the rear rim on the Zondas for brake wear. It took a crash for the Shamal to require truing.

[@CyclespeedTours]

@@thomaslutro5560 I had Lightweights, but I think the Boras are better. Great wheels.

[@fredlast4547]

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

[@CyclespeedTours]

Fair enough - I have rides like that too sometimes. But other times I like to go as fast as possible and shave off some seconds!

[@Jeebus0143]

Great then don't buy the Fuking wheels lol.

[@whatyoudo9773]

yet you clicked on the video...need a hug maybe? Pat on the back?

[@prblakeslee]

To each their own.....for me getting my bike dialed-in (and understanding the science) is very rewarding. And seeing measurable results (30 seconds is huge!) from my efforts is even better!

[@paulflory3532]

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.

[@CyclespeedTours]

I would agree with all of that. The trend right now is very much for aero, aero, aero and I do get it, but light wheels just feel very, very nice to ride and you can't quantify snapiness out of corners or 'flickability'.

[@23ofSeptember]

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

[@CyclespeedTours]

Sorry, not sure, never tried them

[@dickieblench5001]

I have these. They are aero with very few spokes so good for TTs but don't use them in a twisty crit they flex badly!

[@martinb4272]

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?

[@CyclespeedTours]

By broadest you mean bladed right? But the fewer spokes the better, aero wise, less things attacking the air

[@MozOnBikes]

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.

[@CyclespeedTours]

Good questions, and it's hard to know the answers of exactly how they test, but unless they have a power monitoring device on each wheel, they cannot know the power to spin

[@tobuslieven]

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.

[@CyclespeedTours]

Yes it is true. It has a velocity v the same as the bike, but also a velocity v in rotation, = 2v. Thanks!

[@apollocreed3263]

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

[@kjbeaud]

Agreed. C24 wheelset is amazing on my trek emonda sl6. They spin for days and make the bike a dream to ride. Sure they may not look as cool as some deep section wheels but i dont care. Ill pass a majority of those riders anyways on flats and climbs.

[@b2theb]

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!

[@CyclespeedTours]

I think you're confusing rotational inertia with rotational drag. It's Power to Spin, not Power to Spin Up. Power to Spin is power that is required all the time, even at a constant 40km/h say, as you have to overcome the drag on the spokes, etc. (+a small amount of bearing drag). DT Swiss has calculated that rotational drag makes up 25% of the total drag, so quite significant. Part of the reason deep wheels are aero is that the spokes are shorter, and therefore their tip velocity is decreased. A disc wheel is the ultimate as there are no spokes attacking the air at all.

[@b2theb]

Cyclespeed Tours look clever clogs, couldn't u just say, I know what, I think you're right? thanks for the in depth reply....u have a new subscriber.

[@CyclespeedTours]

LOL, welcome!

[@albr4]

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.

[@CyclespeedTours]

Hi. Sorry but no. Bearing drag is linear (as speed increases) and relatively minor. Spoke and rim drag increase with the SQUARE of the speed and become very high at high speeds. Spin a wheel up to 40km/h, It slows rapidly to 25km/h. Why? Aero drag on the rim/spokes.

[@vincentvergara2728]

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

[@CyclespeedTours]

Assuming they're bladed then the thin side attacks the air, i.e. in line with rotation.

[@tpinkerton1965]

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.

[@PeakTorque]

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!

[@CyclespeedTours]

Hi, and thanks for the detail on bearings which makes sense, but as you say, it seems the drag is linear 'enough' for our purposes. Yes, green mosaic, to make it look 'natural', but can be mistaken for algae!

[@PeakTorque]

I couldn't see the mosaic on my phone screen, there were obviously more than 480 tiles across the screen at the time :) You are a lucky man - clearly not on an engineers wage ;)

[@CyclespeedTours]

Yeah, guess you need Ultra HD for that! Houses are cheap as chips in France, sometimes they can't give them away. Here's a better look at the pool; vimeo.com/219205227

[@stockman1963]

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.

[@CyclespeedTours]

Hi Stockman and thanks. I did in fact do something very similar to what you suggested. Using a drill with a known speed (50kmh), I spun up a Corima MCC S+ and a Lightweight Meilenstein in a stand. Then watched and recorded the spin down times. The test was done quickly and was not scientific enough, but it did show the LW performing far better than the Corima, due to the Corimas fat round spokes. Many commenters said it was just the difference in bearing drag, but this was not the case as the slow down was not linear (aero) and you could even hear the extra air movement of the Corima. I did not have a big fan present, but that was my next step idea. The 'static' test was unrepresentative of real world conditions, as no translational air movement, but it did form a basis to show that the ROTATING aero design is important.

[@whatyoudo9773]

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!

[@CyclespeedTours]

kzbin.info/www/bejne/op7UlaSZhNulosU 1 hour and 30 seconds

[@damienmills293]

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.

[@CyclespeedTours]

Well done for 'crushing' the KOM! Clearly if it's a technical descent, then braking, cornering, etc. are far more important factors than aero. I think just about everyone now knows that the rider makes up to 80% of all aero drag, and position is key, but there's no harm in looking at aero aspects of the bike too. I'm quite happy on the LW's (and Corimas) in the mountains - I work as a tour guide, so I think I know what I'm doing. But wet braking is poor, and I will sometimes grab an alloy rim from the support car. That vid was just me out messing around - I have and use shoe covers for races (best aero bang for the buck), I have skinsuits (with rear pockets unfortunately!), have a TT Helmet too which I don't use much these days, sometimes go gloveless, have a position which is way more aero than my peers, not sure about a second bottle -jury's out on that one, shifters already quite low on the curve and I like them like that. Stack height? It's slammed. 130mm stem.

[@melbman43]

Thank you very much.

[@CyclespeedTours]

You are welcome!

[@fiddleronthebike]

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)

[@CyclespeedTours]

The Lightweights should do fairly well at 0' and low yaw angles, but in theory are more susceptible to sidewinds, not that I have any problems with them. I agree that air resistance is a function of velocity squared, and power = velocity cubed. And I agree that power to overcome bearing friction increases with speed. From SKF's website; NR = 1,05 x 10-4 M n , where Nr = power loss (in watts), M = frictional moment of the bearing and n = speed (rev/min). Therefore power loss in the bearing increases linearly with speed.

[@lobuxracer]

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

[@CyclespeedTours]

Indeed, which only serves to complicate matters!

[@mikekrasovec6390]

This is one of the main reasons for why knobby mtb tires are so much slower than smooth tread road tires (at higher speeds).

[@jdodd1258]

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

[@CyclespeedTours]

Generally less, as you have shorter (slower) spokes. Spokes 'attack' the air, the rim does not.

[@jseski9209]

spokes can 'attack' the air, no argument there. however, while the rim does NOT attack the area, it has a whole lot more mass. so a deeper section rim, would have greater weight distribution to the outer dimension of the circle (all other things being equal - just taller rim walls & shorter spokes) which would create greater rotational mass...right? Once up to speed, that extra rotational mass would/could work in your favor as rotational momentum, but getting up to speed would require greater watts.

[@sonofsun4]

The larger mass of the rim(on aero wheels) then translates to more energy consumption during the climbing the hills, where the drag is minimal due to slow speeds.The weight of the tire and inner tube, rim and nipples makes a lot of difference. Also the pressure.....some Wredestein tires go up to 170 pound...I use them and I see the difference in rolling resistance compared to other people riding at 80-120 pounds. But only on smooth asphalt and the grip in curves and braking distance is not so great. The flat spokes leave too much of un-flatten area near the rims, that is also bad,because right there the turbulence of rotating wires is max. Nobody talks about these details

[@ScienceSeance]

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?

[@CyclespeedTours]

Some truth in what you say, but it adds a big layer of complexity to test power to spin when testing wheels on the bike. And remember that wind tunnel time is very expensive. Far simpler to just concentrate on 'normal' drag figures. But when wheel's aero performances are now so close to each others (for a given depth), it strikes me as disingenuous to not measure how 40km/h of air movement is affecting the rotational drag of the wheel. Some will perform better than others. The proof is the time and money that DT Swiss are investing in this area. To my mind, far better to have hidden nipples (!) and ultra aero spokes than 1W less at 13' of yaw.

[@mariojavier1623]

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?

[@bee_whisper]

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 .

[@CyclespeedTours]

Hambini, DarkInstall and I are all totally unbiased and unsponsored and will tell it how it is. I think it helps to have an engineering background (me, mech, Hambini, aero, Darkinstall, er, hardcore?!) With the huge budget that GCN have, I'm surprised they don't do more detailed, scientific testing.

[@bee_whisper]

i think half the audience would fall asleep and the otherhalf (me included) would be really fascinated . p.s im a uni student doing wildlife conservation and unbiased videos are the way forward tbh .

[@CyclespeedTours]

Indeed - you can't please everybody all of the time. I sometimes watch GCN when I'm tired, with some popcorn.....:)

[@sarethums]

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

[@CyclespeedTours]

In theory yes - the deeper the rim, the more susceptible to side winds, but the new toroidal shape rims help in this respect. (A bit!)

[@carlosflanders518]

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

[@CyclespeedTours]

Depends on your speed I guess, but sounds about right, thanks!

[@carlosflanders518]

I need to look up my notes, but pretty sure it doesn't depend on speed.

[@CyclespeedTours]

I just mean that the rotational drag will vary a bit between V=0 and V = say 45km/h. It will not spin the same in still air as in moving air.@@carlosflanders518

[@carlosflanders518]

​@@CyclespeedTours Yep. Gets a bit more complicated when the air is moving. Did some basic maths and, for still air, the rotational drag is a constant fraction of translational drag for all speeds. Bring wind in and it's not obvious how it relates. I need to sit down and run some calculations when I have the time.

[@buster0004]

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.

[@CyclespeedTours]

Interesting, and maybe they are not an out and out aero wheel, but they are not so dissimilar to most of the other 'aero' wheels out there. Anyway, I'm not claiming anything special for the Meilensteins, I just like the way they ride, and they're light. I'd like to have a 'super-aero' wheelset as well, but funds don't permit at the moment!

[@ashleydarby3652]

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

[@RishabhGKoenigseggRegera]

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

[@andy-the-gardener]

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

[@CyclespeedTours]

It's not a bad idea and I know several people have tried this in the past. It's worth a bit more investigation.....

[@dvearn7745]

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

[@garynakauchi757]

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

[@firstname7780]

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..

[@gruminatorII]

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 ;)

[@CyclespeedTours]

Yes of course.

[@mindciller]

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

[@mindciller]

@@NetomaMusic a disc is best, then a two spoke, then a three, then a five, then bladed low spoke count. Prove me wrong put a fan in front of the wheel and spin it back up with the drill

[@csantos2]

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.

[@peterliljebladh]

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

[@CyclespeedTours]

In a 'normal' wind tunnel test, if the wheel isn't spinning there is no rotational drag. If it is spinning then it will change the results, but the key point is, how much power does it take to make it spin? That is what DT Swiss have been looking into.

[@BaxterRoss]

In a normal wind tunnel test they rotate the wheel but they only measure the drag linearly in relation to the direction of travel - they don't measure the amount of energy required to maintain the rotation of the wheel itself.

[@CyclespeedTours]

Thanks Baxter, I think you're explaining this better than me!

[@veganpotterthevegan]

Easy, aerodynamic tests test aero drag...the rotational drag is a very small drop in the bucket with a 150lb rider mounted on top of them

[@indonesiaamerica7050]

@@CyclespeedTours Of course those factors are tested. They just don't publish everything. The first "aero" wheels were disks without any spokes because that was the very first thing that they were concerned about. Fluid dynamics is very complicated and marketing folks don't have much confidence in learning everything that they must learn and then translating it to their potential buyers.

[@nathanjimenez1562]

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.

[@megaspongebob6]

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?

[@CyclespeedTours]

Nice idea, but you are improving the part that has the lowest velocity (close to the hub) whereas best gains are to be had at the other extremity, near the rim, where spoke velocity is higher.

[@CyclespeedTours]

True, but still makes sense to concentrate on spoke tips, (although any aero gain is a good one!)

[@enlightenedidiot9552]

se7enTse7en yeah thanks...

[@havefunandbikestuffOver40]

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

[@CyclespeedTours]

Thanks! DT Swiss have a good range and Bontragers are pretty good too. Lots to choose from, but hidden nipples is good!

[@mikekrasovec6390]

Hidden nipples are great for national caliber racers and above but a pain in the ass when it comes to working on your bike. Unless you're a pro I strongly doubt that the aero advantages are anywhere near worthwhile. I will also point out that at any local race every 3rd bladed spoke is rotated at least 45 degrees if not 90 negating the aero performance in real life on their expensive race wheels - on 2 out of 3 bikes. I've seen a LOT of examples of sub par wrenching on racers bikes. Yes bladed spokes are more aero when done right but most of them aren't done right. Adding another way to make it a bigger pain in the ass to work on a bike will reduce the likelihood that it is wrenched as good as it can get. That applies to both riders that work on their own bikes as well as the ones that are handed over to a "pro". An out of true wheel isn't as fast a wheel trued to 0.5mm (or better). I will also add that I've seen a few racers drop out of races because they busted a spoke on their ultra low spoke wheels. When you break a spoke on a 28 or 32 spoke wheel you can open the brake and still ride. With a 16 or 20 spoke wheel if you pop a spoke the bike will probably be unrideable. Especially if it's with the paired spokes.

[@dho]

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.

[@CyclespeedTours]

Indeed, DT make some of the best hubs out there. Simple, light and reliable. Aero is about picking the low hanging, cheap gains first, and then if you want to go further, spend a bit more to get the extra watts, but it's the old law of diminishing returns....!

[@kamilvinca3621]

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 :-)

[@DoomNerd67200]

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

[@Jcool721]

I like momentum :-)

[@CyclespeedTours]

Who doesn't?!

[@georgejgilles.3999]

Very detailed video.

[@RickRubinesque]

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.

[@CyclespeedTours]

I don't think I'm disputing that...? But if a certain wheel is 5 seconds faster round that track you don't know how much of that gain is down to rotational or translational aero savings.

[@TomEnduro]

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..

[@74_Green]

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.

[@CyclespeedTours]

Hi - yes, they usually are, as the valve area is always the heaviest point. Not sure it matters much though......:)

[@enlightenedidiot9552]

Darren Green the valve stem ends up at the bottom? wow, you heard of gravity?

[@attorreatravere4590]

Check Ronald Kuba's channel, he puts tungstene patches (sold in tennis shop) to improve the balance. FKC wheels are designed with a single sticker glued to the opposite of the valve. Last thing : being cautious while gluing a tubular tire to make sure it's in a perfect round shape. Cheers folks.

[@CarlForde]

the faster the wheel rotates, the more it matters. An out of balance wheel can cause a speed wobble, or annoying vibration that you can't get away from. Also, as ever, smoother is faster. There are a variety of ways to add weight to counter balance the valve stem to balance the wheel. It only takes a few minutes

[@JSSBBB]

Next time, do the video without the birds.

[@CyclespeedTours]

I don't control nature dude!

[@hchernandez03]

where can I get that t shirt?

[@CyclespeedTours]

Hi Henry, drop me an email at [e-mail] and we can check your size/colour/shipping. You can also enter our 1000 subs competition (if you're quick!) to win one!

[@paulflory3532]

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.

[@CyclespeedTours]

Hi Paul - good points. Total wheel drag is not huge when compared to the human rider him/herself, (up to 80% of total drag) so 25% of that is of course smaller still....marginal gains and all that..! Drag force is related to velocity squared, and power required to overcome that to velocity cubed, so speed is obviously crucial when discussing drag. At low speeds (

[@Greenjuiceman]

thank you

[@CyclespeedTours]

Very nice of you to say so! Thanks.

[@crudestinkyjoe]

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

[@fat2fit691]

good insight

[@ironmantooltime]

why is bearing drag linear?

[@CyclespeedTours]

Because it increases as a function of the speed (rotational speed, rpm in this case). (Or at least linear enough for our purposes).

[@ironmantooltime]

Cyclespeed Tours ok thanks, as you're a mech eng I'll give you the benefit of the doubt 😀

[@CyclespeedTours]

:) Happy to be corrected if wrong, but SKF's website gives this formula; Power loss = 1,05 x 10-4 M n , where M is the frictional moment of the bearing and n is the rotational speed (rpm). (But at extremes (very low/high speeds) the linearity can break down).

[@ironmantooltime]

Cyclespeed Tours the xtreme low speeds may apply in my case, cheers!

[@CyclespeedTours]

:)

[@stanvandernat]

Good info! Need a mic. Tho

[@CyclespeedTours]

Thanks! Got one now! (But it's a pain to use)

[@sonofsun4]

Yes, indeed, the wheel building companies are lying a lot. Because not only rotational wind drag is very important(nipples at the rim or at the hub, flat oval or round spokes, number of spokes in the wheel....they never mention the differences in energy requirements), but also wight of the rim itself and nipples at the rim makes a lot of difference in energy requirement. And it is almost impossible now days to find the weight of the rims used almost on any wheel set. It used to NOT be like that 20 years ago. You could find the complete spec on just about any rim. Not any more....It is all just white lie....

[@gruminatorII]

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

[@CyclespeedTours]

Why is bearing drag not proportional to speed? What is it proportional to then? Aero drag increases with the square of speed which is a form of exponential.

[@onilovni1234]

More and more I keep telling myself aero carbon wheels aren't necessary. They sound nice, and yet I've seen a up of 1,5 kph with my aero wheels, but they aren't worth the money compared to 350$ Shimano wheelset.

[@frenkvortice3858]

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.

[@CyclespeedTours]

Specially for you; kzbin.info?o=U&video_id=FubJV2N9dyY

[@floblang]

Shouldn´t the "rotational drag" equal the weight of the wheel? If 2 wheels have the exact same shape but differ by 100g the lighter one would have less rotational drag. That lighter wheels are easier to accelerate is no secret, once they´re rolling though the rotational weight is much less important than the aerodynamic properties are. I don´t think that this is some kind of secret. Cyclists aren´t only obsessed about aerodynamics but weight, too ;)

[@CyclespeedTours]

Rotational aero drag has nothing whatsoever to do with weight - it's all to do with the shape of the rim, spokes, nipples and hubs.

[@magicf7076]

So, what are you trying to tell us??

[@RevoltingRudi]

Buy a Powermeter. slap on that shiny Wheels. Go to a Velodrome. Do some testruns if they let you with fixed power output. f you are faster with the new wheels consider buying. if you are slower, send them back.

[@frankhutton6747]

A Few things, Firstly wheel making companies do usually look at rotational drag and have that as a selling point. Secondly, you seem to be confusing rotational drag and rotational inertia. Much of what makes a bike harder or easier to accelerate is the weight of the rims rather than the rotational drag. And, Thirdly

[@CyclespeedTours]

Firstly, really? I haven't seen it mentioned much until DT Swiss. Secondly, no, I'm not. I don't mention 'accelerating the rims' at any point. We are looking at rotational drag here, which, at constant speed, is independent of inertia. A heavy (or high inertia) wheel may perform very well in rotational drag. But yes, heavy, high inertia rims are harder to accelerate. Thirdly?!

[@frankhutton6747]

Firstly, Just because you haven't seen something doesn't mean it's not there. I certainly have seen many a promo video on the topic. Secondly, you specifically say "how much energy it takes to spin the wheel" so you are at the very least choosing poor wording. This is the same problem I had with your first video where the rim weight would have much more of an effect than the rotational drag on the spin time. And thirdly, if you say the rim profiles are "all pretty much the same" then how does the rotational drag change? If the rotational drag changes it certainly negates your first point about aerodynamics all being the same for all different wheels brands. Sorry for the paragraph

[@CyclespeedTours]

i'd be happy for you to point me in the direction of wheel makers discussions of their r.drag. I'd be genuinely interested to see it. We're talking about the power to spin (which can be reduced to 'energy to spin'). Inertia is not a factor in this video. For the earlier video, I did specifically mention that both wheels were the same weight, and that their moments of inertia were very similar, close enough for the purposes of the experiment. You can have 2 wheels with very similar rim profiles, but one has better r.drag characteristics than the other, eg. better shaped spokes, hidden nipples. The rim shape will not have much effect on r.drag, but does have a big effect on translational drag. My point was that many rim shapes are very similar these days, and will give very similar trans.drag performances. However, an area open to optimisation seems to be r.drag. But let's not kid ourselves, all 50mm wheels are going to be pretty close to each other aero wise, no matter how good their r.drag.

[@pauld964]

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.

[@CyclespeedTours]

Care to elaborate? Once up at high speeds (30km/h+) the overriding factor is aero drag and bearing resistance only plays a small part. This is borne out by the much faster deceleration from 40 to 20km/h than 20 to 0.

[@pauld964]

I have two sets of Zipp 404 Firecrest Tubulars running both running Vittoria Pista CS tyres inflated to 10 bar the only difference between these two wheel sets is that one set has standard Zipp precision swiss while the other set has the optional CeramicSpeed upgrade. The rate of deceleration between these two wheel sets is noticeable when then wheels are spun free as such I believe that bearings performance, not to mention wheel weight 'can' play a greater part than you imply. Ultimately your not comparing like for like imho. Comparing an incredibly light wheel (Lightweight claims 475g for the Meilenstein front) while the Corima 47mm deep front wheel has a claimed weight of 525g but no discussion regarding the impact that this will have on rate of acceleration and deceleration at a given power took place. I'm not for a moment suggesting your incorrect only that your testing process is flawed and that you are painting an incomplete picture and presenting 'selective truth' to get your point across.

[@CyclespeedTours]

Thanks for the reasoned comment. The LW is not actually quite that light - from memory there was only 10g difference between the 2 front wheels. And as their construction and depth are extremely similar, I think it reasonable to assume a very close moment of inertia. Certainly the differences I was seeing in slowdown rates could not be attributed to mass or inertia. But as I mentioned, that video was an early one, set up very quickly, filmed quickly, and would have been much better with a speed sensor, amongst other things. One would expect 2 identical wheels with different quality bearings to show different slowdown times, but I would wager that the 40/20 drop would be extremely close whereas nearly all the difference would come in the 20 to 0 drop. There is no getting away from the fact that 20 spokes each approx 30cm long spinning at 40km/h+ move a lot of air. And drag is related to speed squared. So it makes sense that the dominant force at high speeds is the air drag, not bearings.

[@89gregpalmer]

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.

[@CyclespeedTours]

So do you think that when a spoke moves through the air it is, by some mircale, 'drag free'? Think it through.

[@89gregpalmer]

Cyclespeed Tours that’s aerodynamic resistance or drag. Not rotational drag.

[@CyclespeedTours]

@@89gregpalmer It's drag caused by the spoke rotating, as opposed to drag caused by the spoke moving linearly. You have to apply energy to get the spoke to move in a circle due to a) the air drag and b) the bearing drag

[@89gregpalmer]

Cyclespeed Tours oh I see, you are talking about the effect that rotation has on the overall aerodynamic resistance. I’m with you now. I originally thought you were inventing a fictional force that would slow a rotating body in the absence of air or friction. I misinterpreted, you are right.

[@aarondrossart6026]

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.

[@CyclespeedTours]

You make some good points, but the power to spin those wheels is coming from somewhere - imagine the spokes were like big paddles - it would take a lot of energy to spin, right? You need to measure that to be sure. Wind tunnels are equipped to measure translational drag, ie. how much the bike (or wheel) is being pushed backwards by the wind. Unless you build a rig to test for r.drag, (like DT Swiss) the equipment isn't there.

[@aarondrossart6026]

Cyclespeed Tours would this not be measured by a power meter? That's what I mean, they certainly have one on the bike

[@litespeed65]

Great review-nice back yard.

[@MicroageHD]

Aren't all wheels tested while actually spinning?

[@CyclespeedTours]

Usually yes, but the key point, which many seem to be missing is that you need to measure the Power to Spin that wheel - if the wheel has huge fat spokes, say, you will need to input far more power to spin that wheel at 40km/h.

[@mitchellsteindler]

Thanks for the video. Wouldn't much of that "power to spin the rim" be captured by the rearward force the spokes experience in the wind tunnel? Isn't that rearward force most of what you are referring to in the power to spin the rim? Additionally, conducting this test while stationary (or not in a wind tunnel) seems almost meaningless. Every part of the wheel is always moving forward, but spokes are experiencing much higher wind velocities at the top of the wheel rotation than the bottom. Given the squared air resistance rule, this factor would be very important, and not at all captured by spinning the wheel while stationary. Certainly bearing resistance is not accounted for my wind resistance tests, and that would be great data to have, but other than that, I don't really understand what is not being captured by the current standards.

[@MicroageHD]

The bottom spokes (below the hub) are moving with the wind, therefor create less wind resistance due to symmetry reasons. The spokes are moving way slower than the actual translational velocity (Omega x r) and their frontal area is very small so the effect will be very marginal. The test with the wheel spinning time until it stops is actually really not a good for any assertions on drag because what you mainly will "measure" or "see" is the wheels moment of intertia. A more sluggish wheel to ride will actually spin longer because of its higher moment of inertia. So what you can conclude from a wheel spinning time test it's is mass and mass distribution. I.e.: (Moment of Interia) J= Volume-Integral of [r² * p(r)]dV.

[@mitchellsteindler]

Microage this exactly what I'm saying plus more

[@BaxterRoss]

They're not measuring the wattage required to rotate the wheel - only the linear drag against the direction of travel.

[@terryr8510]

sounds like a happy bird in the yard

[@CyclespeedTours]

Yeah, I asked them to be quiet, but they refused.....