Aero socks, check. Funky smooth helmet, check. Top tube bag, frame bag, check. Water bottles everywhere, check. USWE pack, plus a hip bag, check. Didn't register, so no number plate. Being that I only usually pedal at about 50 watts on most rides anyway, I now expect the bike to accelerate on its own because I'm implemented so many watts savings. Thanks, awesome video.
And destroying their equipment on top of that. I'll stick to my local races on hero gravel where I'm not wading through "peanut butter" mud or slashing my tires to shreds.
@@GravelRacer1 BWR Asheville $225. Local gravel series near me fetching $100+ to race on open plublic roads. Well over a $1 per mile to race my bike, no thanks.
This is the only wind tunnel video I’ve seen that actually answered the questions we all have without marketing BS mixed in.. Awesome work. I would have loved to see the numbers for that skin suit and S-works helmet tho 🤔
Dylan, at which yaw angle have you performed the tests? What I’m after is that when you ride in real life, especially at gravel speeds, your effective wind angle is usually bigger than on tt (due to speed difference). Therefore, some items generating savings like bigger water bottle at 0 yaw might be costing you watts at 5-10degrees of yaw. I love the scientific approach, great vid as always!
The back hump thing for better aero is a thing outside of cycling too. Motorcycle racers normally have an aero hump on the back of their racing leathers to reduce drag as well.
@@jimjam218 the hump was never intended to be a safety feature. Its pretty soft and actually makes safety worse because the spine cant be straight while laying on the back after a crash.
Race promoters needs to actually enforce proper plate placement if the numbers are that crazy. Huge disadvantage to those who follow the rules. Amazing as always, DJ
or just make numbering aero optimized so people won't try to go around it. Whats wrong with putting it on the side, and maybe also having one front of the helmet? Dumb testing human nature
In terms of number plates, gravel organizers should realize it’s not mtb. They should do road style. A number pinned on the back of the jersey and/or a smaller one on the seatpost
I love this video and it’s a great resource. Quick point about aero bars though, anywhere you can use the aero bars you could also be in an aero hoods position so the penalty on those sections would be 10.3W and not the full 41.4W, while the gain from not having them is 4.5W when you don’t use them. This means you would have to use them 44% of the time to see a benefit which you said is not possible . This makes some assumptions about your core strength and wind speed, but aero bars aren’t actually that much faster if you compare them to the best alternative and not the worst.
But you cant hold an aero hoods position for that long. With comfy set up aero bars you will be still quite a lot faster and can relax your hands and butt. This makes quite a difference for many ultra races.
ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DZnrE17Jg3I.html Take the Specialized 'win' tunnel with a grain of salt, but still there are savings to be had...
I've been so stoked for this episode after hearing about it on the Marginal Gains podcast where Josh answered my question about potential aero benefits of running a 1x setup vs 2x for unbound.
Thnx Dylan! As always, very thorough and deep data investigation. Can you share your opinion on which power zone calculation approach is more relevant based on FTP test? There are a few system in Trainingpeaks, meanwhile Wahoo makes it their own way, meanwhile Garmin makes it different, meanwhile Strava and Zwift suggest another one etc... And the same situation for the HR zones as well.
Awesome video. For calculating how much time you have to ride in the aerobars, should we be comparing "In Aerobars" to "Aero Hoods", the next best aero position, and likely the position you'll take if you don't have aero bars installed? So the aero bars gain 6:00-ish minutes (vs aero hoods) and cost 3:20 (while upright). Doesn't that math work out to say you need to spend over 1/3 of the race in aero bars (6*1/3 ~= 3:20*2/3) versus the next best aero position (1/3 of the race in aero hoods position, 2/3 in upright).
Great video Dylan. Many of your savings from the wt are almost identical to my outdoor tests (protocol is 35kmh) which is awesome yet shocking as i wouldn't often trust the wt at these speeds! But good to know! The hoods to drops position at 35kmh is similarly low, 12W for me.
It's not quite about keeping air attached when we're talking about cyclists, it's simply about filling the void (though attachment has to do with it). You have high pressure up front, and low pressure out the back, drag mostly boils down to that (the pressure differential). So there are two strategies you can use. First is texture so that air sticks to the body longer and creates a smaller low pressure zone behind you (hello aero socks). And second is stuffing. Yes, stuffing. Just put stuff in low pressure areas. It's that simple. Oh and helmets are not individual dependent, they're largely position dependent, people often mix up the two because everyone has a slightly different position (torso angle, head angle, neck angle and shoulder shrug).
The head wind aspect of aero is a good point. I see a lot of people hate on the higher speeds companies quote for aero savings but what you said makes a lot of sense.
I know you had a disclaimer at the beginning of the video expecting you might get some grief for a video like this. But my view is entirely the opposite of that. Thank you very much for sharing this information especially considering the investment of time and money from both yourself in the companies that are supporting you. Super cool and useful.🤘
I realize you probably didn't do replicate tests, but what sort of standard deviation would you expect for wind tunnel tests? Like less than 1W or several watts? Could some of these small differences just be within the margin of error?
I’d be interested in seeing results of different aerobar positions. I read one article where the mantis position was significantly faster than the more parallel to the ground position. Also, what are fastest sunglasses, gloves(or not) and also is a front derailleur slowing you down or giving an aero advantage?
A lot of surprising, but perhaps not so surprising results. Glad to hear a top tube bag not only doesn't increases, but decreased drag! The burrito bag makes complete sense and I'll still never understand why many folks in the rando scene still carry large handlebar bags. It's like a 400k ride isn't hard enough they want to make it harder. Great stuff, keep it up.
That was a pretty small bag he tested...make it larger, and at what point does it start being a "fairing" for the rider? I suspect that somewhat larger bags might actually be helpful (too a point...make them too big and too "square" and they could be worse). Not to mention, it's a good place to mount that mandatory number plate, and in a fashion that isn't flat or concave (like how it was shown being tested). It could be that it's the best solution for a front number plate...10W for a burrito bag w/number plate on it is better than 12.5W for the flat number plate ;-)
Jan from Rene Herse had mentioned some wind tunnel data he has that shows the big rando bags do act as a fairing decreasing drag like a motorcycle fairing.
@@JohnMcQueen Yeah...I wouldn't put too much stock in most of his testing. In the broad sense he gets things "right", but some of the details can be a bit stuffed (he doesn't know what he doesn't know about aero testing IMHO). He also made a blog post about how he had some on-ride descent data that indicated a huge rando bar bag on a round tubed bike was faster than an aero bike...but a quick perusal of the Strava file showed the top speeds he was reporting were obvious GPS-speed glitches. Take out the glitches and his rando bag rides had the slowest top speeds on the descents. He was made aware of that, but never corrected the post :-/
Great vid. I am an aerospace engineer and not much surprises me and frankly delights me! Expect the unexpected in aerodynamics. I am wondering how much effort you would gain closing up the frame entirely. I saw a vid of one of the gravel winners with the top half closed of with some self made plastic housing to contain water and tools and such.
@@chuckyfox9284 yes, did my usual road group ride on a gravel bike with full frame bag. (more fun riding to and from) No issues with head or tailwind, but in the crosswind sections I struggled. Got dropped (and normally don't) on a crosswind section. The joys of living in the world's third windiest city.
The company Swiss Side did test different gravel tire sizes and tire treads in a wind tunnel. A smoother tread is a couple of watts faster than a knobby one. The data can be found on their website
Lots of good info in this video. While it's gravel specific, there's a quite a bit of overlap that can be useful for randoneurring, where rides start at 200km. Slower speeds, more relaxed position, carrying bags and extra water, wider tires, with or without aerobars, etc. Over 200, 300, 400, or 600km, every watt matters. Also, I'd always opt for wider tires. The comfort, control, and puncture resistance gains far outweigh any aero penalty IMHO, especially if it allows you to use aerobars more often.
excellent excellent video @dylanjohnsoncycling. I'm considering many aero upgrades to shorten my time on the 100 mile White Rim trail in a day on a full sun mountain bike. Would the socks, non-sci leg warmers, an aero bottle help in that case?
Money saving tip on aero helmets: Lazer offers an "Aeroshell" for a lot of their helmet models, which is a a plastic shell that clips onto the helmet to cover most of the vents and basically makes it an aero helmet. So for example if you buy the Lazer Strada plus an Aeroshell it's around half the price of the dedicated aero helmet model they offer.
@@filmaynard thanks for the information! I only got mine since fall so I couldn't really test it in hot conditions, but I suspected it might be a little to much for summer
As much as I appreciate all the Intel, I have even greater appreciation for your willingness to ask the questions that everybody wants the answer to but is afraid to ask. So many channels published drivel as "content" cough..GCN. Thanks! Burrito bag stays home for Unbound 200 this year 😮
Another point in favor of running larger tires is if they allow you to spend more time in the aerobars. A favorite of mine are 2.1” thunder Burt’s… they give up nothing on rolling resistance but can float over loose stuff even while in the aerobars!
A combo of a fairly far back aero bar position (knees end up nearly hitting elbows) to be a bit less front heavy and the big tires really make a surprisingly stable setup. Of course still has its limits but yeah
A combo of a fairly far back aero bar position (knees end up nearly hitting elbows) to be a bit less front heavy and the big tires really make a surprisingly stable setup. Of course still has its limits but yeah
This is basically what Ted King said after winning with a lefty suspension. The fatigue prevention of the suspension allowed him to sit tucked for a great deal more of the race.
Dylan, thank you for an awesome video. Could you please speak a little to the sensitivity of the wind tunnel measurements and calibration which you experienced during your study? How repeatable are the tunnel measurements back to back with everything being kept the same? What is the smallest increment of CdA or the equivalent W that the tunnel could measure? If your testing spanned more than 1 day, can you share your control run results across the testing days?
Any chance you did a min/max comparison with worst case Unbound setup compared to all of the best case options done at once? I.E.- in the hoods, number plate flat, regular socks, water bottles etc and then in the drops/aero bars with hydro pack, socks etc...
Ha, I'm a bikepacker, your wiley gravel gains mean nothing to me! on a serious note though, I'd love it if you guys could get another wind tunnel and test some bikepacking gear for aero, particularly if you could get a full frame bag+hydration hose (ie with an apidura bike-specific bladder), and the Tailfin Aeropack. Given my current bikepacking setup, I estimate I lose 12-20w for my front bag (swift zeitgiest), gain back 5w for the full frame bag, and the tailfin gives me back another 5w, even after loading all the extra crap on the outside. So maybe a net loss of 3-5w? Not that bikepacking is about speed and time savings, but my recent bikepacking trips are totaling over 150 miles, and being 4-8hr days that's a lot of potential energy savings.
GCN has done videos for different bike pack setups tested in the wind tunnel. Seat Post pack performed the best for aerodynamics. Search their page for ideas.
I think the most interesting test would be non-aero gravel frame with 700X40 tire versus aero gravel frame and the same tire. In other words, do the bigger tires disrupt the airflow so much that the frame shape is largely irrelevant?
I appreciate why the delta power between configs is useful, but what did you find your overall CdA to be for the different configs? Lionel Sanders (ironman) recently posted his wind tunnel results and he shared CdA.
Your tests showed a 1.6w savings for the tall SILCA socks. I noticed there website advertising a 5w-10w savings. Any thoughts on the difference? Thanks -Ryan
The number plate drag numbers aren't surprising, but at the same time are completely meaningless. If the rules for an event call for it to be flat in front (the worst aero position), so what? Every rider in the race faces the exact same penalty, making it no penalty at all.
Well, you never stop learning. Thanks for this. The hydration pack really surprised me. One idea for a possible future wind tunnel test would be a full frame bag.
Great information. Love the SOG-leveling arguments. Thanks again for introducing a smidgen of sanity to all the vibe talk. It's always fascinating to learn there are still people (newbs?) who don't consider their speed while riding down hills as factors in the aero equation. Unbound may be flatter but it still has about 7-8000' elevation throughout the course. Most of the hills can be freewheeled down at 20mph and, if running any mid-section wheels you'll be able to get almost half way up the next one before putting down real power. The only difficult part for us less-powerful riders will be safely navigating all the mid-packers riding their brakes down the hills in search of their next flat. As for aero bars I use them to gain speed in the wind and, almost as importantly, for comfort on long rides; to take pressure off my hands for a spell. And thanks also for the pack numbers. Really. I have five (5!) run-specific hydration packs, three of which are light weight and two are somewhat aero but I'm now considering the Uswe which I've resisted in the past.
Aero hoods position was the most dramatic yet practical gain for most riders. Minimal penalties for wider tires, hydration and frame bags means staying fresh, hydrated and fueled over long rides is the play and suffering needlessly is as misguided and self-defeating as a reasonable person would expect.
Thank you for some great info! But given the goal of finding out what works for unbound 200, shouldn't you have done all the testing with the full flat numberplate?
Very well done, Dylan, and consistent in quality with all your other videos. I really like it that you're able to make fun of yourself. Keep it up! It lends credibility to your presentation (and makes it more enjoyable).
Can we get race promoters to ditch number plates and use pin on numbers? They serve no purpose other than to try and sell you photos later. We've been racing road for decades with pin on numbers with no issue.
In triathlon we use stickers on seat posts (similar to the pin on numbers) and also on helmets. The promoters can easily sell us photos using these numbers without any aero penalty to the athletes.
What kind of effect do you think rim width has on tire aerodynamics? Would a wheelset like the Nextie AGX45 (29 ID, 40 ED) negate the aero losses with using wider tires?
I'm surprised he didn't test full on overshoes - not only more aero overall but also helps if you need to dip in mud or water - mud does not get inside the shoe from the top.
I'm surprised you didn't test deep section carbon wheels. I've heard from numerous sources, including manufactures that deep section gravel wheels don't make much of a difference. That is for two reasons. First, the air is already turbulent leaving the gravel tire. Second, the ratio of tire width to outer rim width is much wider on a gravel setup therefor the rim isn't affected by the air because of the larger tire.
Awesome video Dylan! I wouldn't have guessed in a million years that my 3rd water bottle in my jersey pocket is actually making me faster! Also I have to admit I kinda want some Rule 28 socks now 😆
@@gregmorrison7320 I put my tool kit in the bottle cage under the downtube in one of those "keg" looking containers. Doesn't matter if it gets all muddy.
Dear Dylan. What is the measurement uncertainty in this wind tunnel test? You are quoting numbers down to 0,7 watts which is very very small. Are you perhaps measuring at higher windspeeds and then adjusting to lower speeds? I am skeptical that these values are meaningful at all. In addition to this, have you taken into account that real wind conditions at low speeds are turbulent, i.e. chaotic, and not at all steady state?
I just posted a link to the test that included that bag among others. The downside of that bag is ~4l of heavier stuff (ie a bladder) changes the handling. If you keep it light, it works well with aerobars. I suppose you could crank the bag to normal handlebars with voile nanos but I haven’t tested that.
Dylan, in regard to time-limited wind-tunnel access, you might consider Design of Experiments (DOE) testing of multiple factors at a time, at least where you'd expect no interference (like changing wheels and helmets) Caveat: I haven't done wind-tunnel specific research on this.
A few suggestions: Try transient wind tunnel. Seriously more expensive, but much closer to the real world data, because IRL the wind never attacks a vehicle from a single yaw angle for any prolonged period. Re tyre sizes: that ideal platform in the tunnel is not the same as gravel in terms of "shakey-shakey", you know. So since bigger tyres at lower pressures are vastly easier on the rider, that would be much less fatigue accumulation over the course of the race. As it has been brilliantly illustrated by Cadex at Ironman, that will allow one to ride faster for longer. You cannot test for stuff like this in the tunnel. Or you have to at least find one of those smart treadmills - you know, those "for the ultimate Strava experience" and plot a long course with constantly adjusting grade, or something. Ideally, you'd glue assorted bits of cable (to simulate roots) and actual gravel to the treadmill belt - to feel those pesky shocks and vibrations.
I did a time trial and they had us pin the numbers on the left rib cage area of our jersey. Myself being smaller couldn't help but notice larger riders have it much easier pinning the number, while maintaining a more flush surface. We should use those programmable LED Lights like you see on bike spokes (or something along those lines).
I always figured the hydration pack would be faster since it seems like it would act as an aerodynamic fairing. The big surprise for me is that bigger bottles are more aero. I also am surprised that the seat tube bottle is more aero than the downtube bottle.
Yeah that was a good take away with the seat tube bottle although most my rides require more than 1x bottle, perhaps one in the pocket and one in the seat tube cage, guess it is experiencing more disturbed air than when on the down tube.
@@gregmorrison7320 my guess is that it helps the rear tire be more efficient than the downtube bottle helps the front tire... Only thing that makes sense to me anyway. Now I'm wondering why the pros don't just hang onto an empty bottle in their shirt pocket all the time.
Interesting about the bottle in the jersey pocket. It makes sense, but I'm sure it's highly dependent on angle. I hate wearing a hydration vest, and am typically not a fan of carrying a bottle in my jersey, but may be more inclined to do so now...especially with the summer races upon us. I was dropped from the lead group at a water station at a race this year as I wasn't carrying enough water on me (though I found it simultaneously annoying and amusing that they purposely drilled it at that point once they knew I stopped). Of course the other side of that equation is carrying that extra mass up every single hill on course as well.
Bike number plates are pointless. The numbers change from race to race, so there is no consistency with which athlete they correspond to. And when races are televised they NEVER put the riders number next to their name, so you can't even tell who the rider is from the number anyways. And since no cyclists put their names on their jerseys, it's a guessing game to figure out who is who unless you are extremely familiar with each rider's form. Honestly I think it is a big hinderance to attracting new people to watch the racing.
How many Watts did the loose jersey at the upper back of the shoulders cost? We kept seeing that and were hoping you'd change jerseys and comment on it.
I’d be interested in the calculation of time saving given your actual previous speeds with the variations in speed. Since speed to resistance isn’t linear the variations in speed would be significant. I also wonder the effects of riding in a pack or pace-line. Thanks for the video.
This is exactly why you keep leaving wind tunnel tests with more questions than answers. It's not enough to have a tool when you don't know how to use it. 20 minutes of pointless tables that workes on paper in the laboratory, but once you leave the wind tunnel you'll notice that there are more variables at play to consider. Like comfort. Good luck completing Unbound with your whole watter supply on your back. I know people are stupid and like these numbers, probably even more than comparing weights of different screws and components, but let's face it, it makes no sense.
The Aerocoach testing on bottle placement was done an an indoor velodrome (close to 0 degree yaw I assume), and only one bottle & cage was tested in different placements. Those results would be quite different from two bottles with various yaw angles taken into consideration.