We Tested Gravel Equipment in a Wind Tunnel and the Results Were Surprising
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- čas přidán 2. 04. 2023
- We took my gavel bike to the wind tunnel and tested a lot of the aero questions that gravel riders have like tires, packs, on bike storage, aero bars and more. The results were genuinely surprising, enjoy!
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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.
You sir, are a winner!
After more than one year of riding aero, did the bike manage to pedal an entire season on its own?
The only thing ruining gravel are the ever increasing ridiculously high entry fees.
Absolutely. Spending more to race on a dirt road than an entry ticket to Disneyworld isn't normal.
And for what exactly are we paying? People should just start free to join races via facebook and force paid events to ACTUALLY BRING VALUE.
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.
How much are the fees your paying? Where I am they are between $100 and $150. Local races thou.
@@richardmarzec9136 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.
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.
So true
That hump stems from preventing the riders head and spine smashing backwards in the event of a crash. Aero was an after thought.
@@jimjam218 That's what I thought, but articles suggest its just aero.
@@aaron___6014 Damn. I learned something. I also thought the motorcycle humpback was crash protection.
@@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.
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 🤔
BHD approves this comment 😎
Yes, thank goodness we didn't have to hear about "for the win" one time.
when will zipp just go ahead and make a gravel aero disc wheel with like 23mm internal width, optimized for 45mm? BHD demands it...
The only problem is cracked rims from the jumping rocks. Man that would put the warranties to the test.
@@kaseycarpenter73+28mm internal at minimum
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
MidSouth had people walking the starting corral to make sure people 1- had a number at all and 2- had them mounted appropriately.
Would be nice to know the error margins for these tests since a lot of the results are in the +-1W range
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!
I gravel race with 28mm slicks treated with flex seal. I am the future.
And a TT bike
@@kevrasx scratch that, naked and flannel/ripped jeans body paint is the future
I know it's not really gravel...but I did BWR with 28mm slicks on a SuperSix Evo.
Sorry, seen plenty of this already.
I sawed this bike in half….
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).
You and Silca are a great pairing. Look forward to more!
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'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.
With and without mud comparisons too.
This is excellent!! Another contribution to the sport, Dylan. Thank you for your time, effort and focus.
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 :-/
@@tanhalt Interesting, thanks for the additional details
Even though I'm one of these Roadies you speak of I still watch all your vids. Great content and really insightful.
I learn more about road cycling watching this gravel dweeb than I do watching road cycling channels
That's why my TT bike is going to have a custom seat rail mounted carbon fiber 'tool box' that looks mysteriously like a ducks tail. Great vid.
very like motorcycles tail
@@8paolo96 you got it!
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 😮
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.
Like fairings?
Do you know if closing up the frame would slow you down when you have side wind?
@@chuckyfox9284 depending on the angle and speed it might even act as a sail and make you faster. but it surely could sway the other way around too.
@@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.
I wonder how well would fare old MTB with 26 inch wheels if you would cover them with discs.
I hope you can next test a full frame bag (for containing an Apidura frame bladder).
Thank you Dylan
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.
Kabuto has that only on the Aero R1 and R2 if you want other options and it comes with a face shield magnetic clip on.
The Aeroshell is also hot as balls. I use one on my Lazer Z1, but only when it’s cold out!
@@filmaynard Yep winter or TT use
@@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
Electric tape for the win.
Awesome video. Thank you so much to you & Josh. You guys are great!!
Top notch content as always, Dylan. Great partnership with Silca you have!
Thank you, Dylan and Silca. Great info.
Love it! One of your best videos, thank you!
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.
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.
Putting a water bottle in your jersey basically gives your body an aero headtube like shape (elongated). 3.6W is crazy though.
Your videos are a treasure of info, tech, and important knowledge. Thank you Dylan, for all you do. Cheers.
Thanks for the video! Great explanation about aero for us slower riders!
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).
Awesome video. Like you said, it is surprising to have that much new knowledge about effective changes for gravel racing come to light. Now I got to go get by aero gravel socks ...
Excellent job putting all that together. Planning a 200 mi road event in Jul. Thanks man. And thanks Silca. Using some of their stuff.
Love you done this, I'm always advocating for aero saving when possible even for bikepacking if you want to put a good milage
The first no bullshit video I've seen about aero savings. Good job!
Great video, Dylan. This will be one of your most-watched videos is my guess.
very surprising results! although individual setups account for a huge amount of outliers and inconsistency, this has still changed how I think about aerodynamics in the long run
Huge value in this video! Thanks!
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!
Very good point. Comfort is so critical to staying on the skis.
You don't get nervous staying on the aerobars over heavy gravel?
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.
That graph at the beginning and your explanation is genius 👌
Great stuff Dylan & thanks for another cracking video.
The lower speed , watts saved, and time, make so much sense 🤯
Very informative, thx for making this video Dylan 🙏👌👌
Great Video as always with very valuable content. Thx man!
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.
Fantastic content 👍. You have answered so many of my questions.
love how you've compared the things and gave an explanation. I'd be interested in the results how the different setups add up. Means Helmet, + socks + aerobars + bags vs normal hood position
We need more videos like this on the internet
dude great video! This was so helpful and fun to watch!
Great video Dylan. Awesome info. Thanks
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.
Such a great vid! Thanks for all your work and for sharing!🙌🏽🔝🙏🏾😉💪🏽
Great video!! Keep up the work Dylan
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.
Bravo. As always a brilliant vid backed up with proper science.
Great stuff as always!
On rough gravel on a long course - comfort is a huge benefit of wider tires
Finishing faster is typically the most comfortable position.
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?
Really informative as usual. Thanks
Great insight yet again!
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.
Hi Dylan. Excellent video! What would be really interested for future testing is something like the Apidura Aerobar Pack. I wonder if a pack like that also has an aero penalty or if it could perhaps even help similar to how motorcycle fairings work.
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?
Wow! Great info...almost mind blowing! Thanks!
Another great video. Thanks !!
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).
Absolutely stunning video!
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?
Best aero video so far. I am an amateur but I love driving my touringbike with aerobars to work :p. I knew it makes a lot of difference, now I better understand were that difference really comes from.
You'll be hearing from Pete Stetina's lawyer.
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.
Full frame bag with hydration bladder inside rather than in a backpack.
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?
Great video. Many will forget this is "marginal gains." One thing I didn't see tested is different types of drop bars, and width. One of the things I took from the video is the front "splitter"/disruption sucked more watts (handle bar bag, number plate, etc.) than the rear changes did.
Well done insight and testing.
New it!! About the pack!
Did a 1/2 iron with a pack, got made fun, but had best time recorded to date in that distance.
did you use for both ride and run? Tell us more.....
@@Selfrighteouscyclist it was just for the bike. I am going to try it with the run in Ohio 70.3
Thanks a lot for this video, the content was awesome😉👍👍
I've been waiting on this ever since I heard it leaked on the Silca podcast... and that shirt is awesome.
I am suprised by the difference between a real areo socks and Silca knit aero socks
I'm a recreational gravel rider and only race say, 4 times a year and I aim to be... average, so this info is clearly not for me, but I can't help but stand in awe at the numbers. These gains, specially the position changes, are so massive, they might make even the local club ride more enjoyable. I'll be paying more attention to my position in the future!
This is such an exciting topic! I'd love to see another wind tunnel vid of yours. I wonder how good frame bags, that fill the whole triangle, works. Some of them can contain water bladders, so the loss of the bottles wouldn't be an issue. Also combination of items would be interesting. Like how much penalty are handle bar bag or number plate still giving combined with top tube bag and/or frame bag.
Great insights. The sock question is interesting as I've tried a couple of brands and they were a combination of not comfortable (too thin) and often slipped over the course of a ride, especially a longer one. I think giving up a few watts for 3++ hours of comfy fit is a good trade but a super comfy pair of Aero Socks would be ideal (C'mon Swiftwick).
Suggestion for next wind tunnel test: Put Backwards Hat Dylan in the wind tunnel and stand back and watch time cease to exist.
I'd always been curious about what difference watts made at lower speeds!
I am looking forward to see a lot of bikes loaded out like they are going on a 3 week bike-packing trip
One of your best videos to date.
I used 580mm flat Mtb bar with TT prolong. Was great.
Great stuff Dylan 👍
Thanks for the science and the fun learning
Great stuff man. Thank you very much:
Dylan -- I loved this video! Counterintuitive results are always the most interesting! (And, yeah -- aerodynamics is certainly an area where *nobody's* intuition can really be trusted.) And I enjoy the occasional interjections of "backwards cap Dylan"...
Great job as always!
Thanks for the watts to time savings connection for slower (mortal or recreational riders, or even bikepackers). Something to really think about for those long ride (above a person's regular ride length where they'll be going slower to conserve energy and complete the ride).
I'm looking forward to seeing if that prototype Silca tail bag is release. It definitely would be a good investment to buy.
Fun video. Interested in the results of the 45 cinturato H as that's what I run for chunkier races.
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...
I’m curious about the aero drops position- that is drops with bent elbows. Everyone seems to always test straight arm drops to sell more aero bars
Very interesting video. Thank you !
Maybe the study exist already and maybe that wouldn’t apply in something as muddy as unbound. But what is the aero effect of a mudguard. It would be interesting to see if on a long event the penalty, if any, is offset by the fact that the drivetrain is kept cleaner.
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.
Nice video Dylan. What bottle cages are those. They look really nice. Stop those bottles ejecting on the gravel corrigations.
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.
I'm very curious about my Rapha training tights vs shaved legs. I've always seemed faster when I wear them but I think its just in my head because I feel less air on my legs