We Tested Gravel Equipment in a Wind Tunnel and the Results Were Surprising

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!

Links:
Silca Road to Emporia:

Silca blog on aerodynamics:

Interview with Josh on aerodynamics:

Rule 28 aero socks, get 10% off with code DYLAN:

Silca aero socks, get 15% off with code dylan:

USWE Outlander Pro hydration pack:

USWE Zulo 2 hip pack:

Follow me on Instagram, Twitter, Facebook, and Strava for more content:
Instagram: @dylanjawnson
Twitter: @djdylansjohnson
Facebook: Dylan Johnson Cycling Coach

[adaycj]

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.

[mrvwbug]

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.

[LyfeisByke]

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 🤔

[naf]

The only thing ruining gravel are the ever increasing ridiculously high entry fees.

[sheppa]

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

[lukasztamecki]

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!

[_Doodle-bob]

I gravel race with 28mm slicks treated with flex seal. I am the future.

[redwoodJB]

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.

[tasdrouille]

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).

[zbeekerm]

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.

[JSSBBB]

This is excellent!! Another contribution to the sport, Dylan. Thank you for your time, effort and focus.

[philipa]

Would be nice to know the error margins for these tests since a lot of the results are in the +-1W range

[toddtucker]

You and Silca are a great pairing. Look forward to more!

[emilioc]

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 😮

[samsepiol]

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.

[CamsJungleAquaria]

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.

[trashplaysgames]

Even though I'm one of these Roadies you speak of I still watch all your vids. Great content and really insightful.

[samj]

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.

[colemanmerchant]

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!

[RomanoCortesJorge]

I hope you can next test a full frame bag (for containing an Apidura frame bladder).