For those guessing the wattage penalty of gravel vs aero bike....

[yinzerniner]

Swisside posted a really cool comparison. 40W at 30kph between a typical aero vs gravel bike is huge, much larger than what I would have guessed.

https://www.swissside.com/blogs/news/gravel-report

[Likes2ridefar]

That is a lot more than I thought it would be.

These wheeels maybe even more aero for gravel?

https://www.huntbikewheels.cc/collec...32120913330274

[ripvanrando]

It is much more on real roads with a rider onboard.

40 mm tires are very slow at speed

[fa63]

Interesting data, glad someone actually tested it

I have been riding my gravel bike on the road quite a lot with 40c GravelKing tires. These are the slick versions of this tire. Compared to my road bike, which is not aero optimized, I had at one point back-calculated my disadvantage to be about 20W at 30 kph (which is typically what my rides end up at). My perceived effort is also higher when doing road rides on my gravel bike.

[retropean]

The obvious finally quantified. So then is it safe to say the famous Jan Heine argument is nothing but shilling his type of bicycles?

[geordanh]

Originally Posted by retropean

The obvious finally quantified. So then is it safe to say the famous Jan Heine argument is nothing but shilling his type of bicycles?

Lol. Jan talks a lot of BS. He also says the Steilacoom is faster than many road tires. https://www.renehersecycles.com/a-kn...n-a-road-tire/

I have put many hundreds of kms on Steilacooms and absolutely love them on chunky tech gravel/dirt rides. Amazing grip. The idea that they are faster than slicks is laughable. They are super draggy on pavement and measure like 15 watts slower than a road tire on the RR site as well.

This article from Swisside is interesting though for sure. thanks for sharing.

[tuscanyswe]

Originally Posted by ripvanrando

It is much more on real roads with a rider onboard.

40 mm tires are very slow at speed

40mm tires are not very aero agree but id think knobby tires would be the major difference here. But then again i only glansed at the article.

[NHAero]

These 40mm tires have small knobs and weigh 465g. A 40mm slick would be different.

FWIW - I looked at the last 6 months of 2021 and compared the average mph of my rides on my Strong with 650Bx38 GK slicks at about 40 psi with my Firefly with 700Cx25 at about 80 psi. Given that the Strong got some off-pavement miles and the FF didn't, I averaged 14.34 mph on the Strong and 14.73 mph on the FF (1,863 miles on the Strong and 499 miles on the FF.)

I'm pretty sure that if the Strong was shod with gravel tire with knobs it would be slower.

Originally Posted by retropean

The obvious finally quantified. So then is it safe to say the famous Jan Heine argument is nothing but shilling his type of bicycles?

[fa63]

The Conti Terra Speed tires are one of the fastest rolling gravel tires around, only 1-3W slower than a GravelKing slick or the Strada Bianca Pro HTLR according to testing by Bicycle Rolling Resistance.

The Swiss Side study actually looked at the aerodynamic impact of knobs and found at most a 2W difference at 30 kph.

Originally Posted by NHAero

These 40mm tires have small knobs and weigh 465g. A 40mm slick would be different.

[rice rocket]

Originally Posted by geordanh

Lol. Jan talks a lot of BS.

Don't forget crocs are better than stiff cycling shoes!

[ripvanrando]

Originally Posted by retropean

The obvious finally quantified. So then is it safe to say the famous Jan Heine argument is nothing but shilling his type of bicycles?

You need the double-wide handlebar bag for the full "effect"

[lavi]

Originally Posted by rice rocket

Don't forget crocs are better than stiff cycling shoes!

Nope. The preference is hacked up Birks.



Thread. Drifting.

[geordanh]

Originally Posted by lavi

Thread. Drifting.

The longer an online bike science discussion gets, the probability of the thread devolving into a fist fight about something dumb Jan said once approaches 1.

[lavi]

Originally Posted by geordanh

The longer an online bike science discussion gets, the probability of the thread devolving into a fist fight about something dumb Jan said once approaches 1.

Esp here.

Sorry to the OP. The topic is interesting. For me, it's a non-event as all my rides these days are party pace.

[Upcountry]

Thats a really well done and well presented study. I doubt it will put to bed all the misconceptions of road vs gravel setups(see above for exhibit A), but its hard to argue with the results they've gotten.

As a guy with 45mm deep "aero" wheels on my gravel bikes, even with my 40mm tires, I feel slightly validated. Hahaha.

Additionally, There are some takeaways that you could extrapolate elsewhere, and onto just pure road wheel/tire setups. A big one for me was how minimal the aero cost was in going a full 5mm wider in tire width, with the same tread. For that, we're talking 4-5 watts on the jump from 35mm to 40mm or 40mm to 45mm. So with that, its pretty safe to assume that making a 5mm jump from 28mm slicks to 32mm slicks should be on par with, if not less than, that 5 watt number. In reading more and more about ultra distance stuff, there are a lot of people who seem to be against 30mm or 32mm tires for a bit of added comfort, using the aero cost as a main argument against it. Its already been well documented that a wider tire can have a lower rolling resistance at its respective(appropriate) pressure, so this article only adds more data as to the benefits of big rubber.