Rene Herse Gravel Myths #1 - Too Much Tyre

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gorkypl
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by gorkypl

AJS914 wrote:
Sat Jan 07, 2023 8:52 pm
He sells all sizes of tires. Why would he bend the truth to sell larger tires?
Because there is (or was) much less competition in the bigger sizes than in the road segment.
AJS914 wrote:
Sat Jan 07, 2023 8:52 pm
I believe Herse based on my personal gravel experience. That is:

I have a really light S-Works Crux with 38mm tires (40mm actual). My buddies bought Salsa Cutthroats which are drop bar mountain bikes with 60-65mm+ tires.

They were faster than I was in practically all of our gravel riding situations. In rocky or sandy sections they would just ride away from me and my 40mm tires. On smooth sections, we'd all be together but if there were occasional sandy sections I'd have to work extra hard to stay with them.

Sometimes, I'd have to walk sections that they could ride through.

I guess my bike would have a small theoretical advantage on climbs.
Jan's message is not that 60mm is better than 40mm on rough surface.

His main point is (without diving into nuances) that there will be no penalty in coming on your Crux with 40mm tyres to a road race where all other participants are riding 28mm tyres. I do not find this to be true.

Fuji Cross 1.5 - Shimano 105 5800 | Cinelli Superstar Disc - Record 12s | Custom steel Karamba - Ekar 13s

Vespasianus
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by Vespasianus

stoney wrote:
Sat Jan 07, 2023 12:53 pm
The bigger the tire the bigger the aero penalty. It especially matters for fast gravel races with any asphalt sections.
He tops out at 18 mph. Does that play a role in how much "aero" loss he sees with a larger tire?
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Singular
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by Singular

Vespasianus wrote:
Mon Jan 09, 2023 12:37 pm
stoney wrote:
Sat Jan 07, 2023 12:53 pm
The bigger the tire the bigger the aero penalty. It especially matters for fast gravel races with any asphalt sections.
He tops out at 18 mph. Does that play a role in how much "aero" loss he sees with a larger tire?
That's one of the things I get hung up on; it is measured at a very low speed (and at a descent, where the higher weight and larger diameter also help keeping speed up). The industry standard 30 mph/45 kph might be a bit rich for a gravel tyre, but checking my last race on gravel we did the first hour at 37 kph (and that was with more than 500 vert in that hour) so it's not really that far out.

By comparing with an average, one is missing out on one very important factor - half of the time, you'll be going faster than that (which amplifies aerodynamic gains/losses). Anyone that contests the limited value of an average is welcome to do a 20min effort at 90% and 20 mins of 60/60s averaging out the same, and letting me know which one was the least pleasant... :)

gorkypl
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Location: Poland

by gorkypl

Singular wrote:
Mon Jan 09, 2023 1:23 pm
Vespasianus wrote:
Mon Jan 09, 2023 12:37 pm
stoney wrote:
Sat Jan 07, 2023 12:53 pm
The bigger the tire the bigger the aero penalty. It especially matters for fast gravel races with any asphalt sections.
He tops out at 18 mph. Does that play a role in how much "aero" loss he sees with a larger tire?
That's one of the things I get hung up on; it is measured at a very low speed (and at a descent, where the higher weight and larger diameter also help keeping speed up). The industry standard 30 mph/45 kph might be a bit rich for a gravel tyre, but checking my last race on gravel we did the first hour at 37 kph (and that was with more than 500 vert in that hour) so it's not really that far out.

By comparing with an average, one is missing out on one very important factor - half of the time, you'll be going faster than that (which amplifies aerodynamic gains/losses). Anyone that contests the limited value of an average is welcome to do a 20min effort at 90% and 20 mins of 60/60s averaging out the same, and letting me know which one was the least pleasant... :)
Also remember that we often ride with headwind. Doing 25km/h against 5m/s wind gives around 43km/h effective aerodynamic speed.

Fuji Cross 1.5 - Shimano 105 5800 | Cinelli Superstar Disc - Record 12s | Custom steel Karamba - Ekar 13s

spartacus
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by spartacus

He's right, that's why Pogacar won the tour de france on 44mm tires.

spartacus
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by spartacus

gorkypl wrote:
Mon Jan 09, 2023 11:27 am


His main point is (without diving into nuances) that there will be no penalty in coming on your Crux with 40mm tyres to a road race where all other participants are riding 28mm tyres. I do not find this to be true.
No he's definitely right. I would highly recommend anyone that's racing against me or competing for strava segments starts riding with 40+mm tires on the road ASAP!

spartacus
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by spartacus

gorkypl wrote:
Mon Jan 09, 2023 2:22 pm
Singular wrote:
Mon Jan 09, 2023 1:23 pm
Vespasianus wrote:
Mon Jan 09, 2023 12:37 pm
stoney wrote:
Sat Jan 07, 2023 12:53 pm
The bigger the tire the bigger the aero penalty. It especially matters for fast gravel races with any asphalt sections.
He tops out at 18 mph. Does that play a role in how much "aero" loss he sees with a larger tire?
That's one of the things I get hung up on; it is measured at a very low speed (and at a descent, where the higher weight and larger diameter also help keeping speed up). The industry standard 30 mph/45 kph might be a bit rich for a gravel tyre, but checking my last race on gravel we did the first hour at 37 kph (and that was with more than 500 vert in that hour) so it's not really that far out.

By comparing with an average, one is missing out on one very important factor - half of the time, you'll be going faster than that (which amplifies aerodynamic gains/losses). Anyone that contests the limited value of an average is welcome to do a 20min effort at 90% and 20 mins of 60/60s averaging out the same, and letting me know which one was the least pleasant... :)
Also remember that we often ride with headwind. Doing 25km/h against 5m/s wind gives around 43km/h effective aerodynamic speed.
According to JH, wheel and tire aerodynamics are basically irrelevant, and since he's right, I wouldn't worry about it. You can still win the town sign sprint against someone doing 20w/kg on a specialized tarmac on a steel bike and 50mm tires!

froze
Posts: 430
Joined: Thu Aug 05, 2010 3:47 am

by froze

spartacus wrote:
Mon Jan 09, 2023 5:25 pm
gorkypl wrote:
Mon Jan 09, 2023 11:27 am


His main point is (without diving into nuances) that there will be no penalty in coming on your Crux with 40mm tyres to a road race where all other participants are riding 28mm tyres. I do not find this to be true.
No he's definitely right. I would highly recommend anyone that's racing against me or competing for strava segments starts riding with 40+mm tires on the road ASAP!
I have a pretty good feeling that Pogacar could beat me badly if he was racing against me using 60mm tires and I was running 28s!

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Lelandjt
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by Lelandjt

Vespasianus wrote:
Mon Jan 09, 2023 12:37 pm
stoney wrote:
Sat Jan 07, 2023 12:53 pm
The bigger the tire the bigger the aero penalty. It especially matters for fast gravel races with any asphalt sections.
He tops out at 18 mph. Does that play a role in how much "aero" loss he sees with a larger tire?
Marathon runners draft each other. Yes, aero matters at speeds as low as 10mph. It matters less than at high speeds but when distances are long those small differences add up.

stevesbike
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by stevesbike

Lelandjt wrote:
Tue Jan 10, 2023 7:25 pm
Vespasianus wrote:
Mon Jan 09, 2023 12:37 pm
stoney wrote:
Sat Jan 07, 2023 12:53 pm
The bigger the tire the bigger the aero penalty. It especially matters for fast gravel races with any asphalt sections.
He tops out at 18 mph. Does that play a role in how much "aero" loss he sees with a larger tire?
Marathon runners draft each other. Yes, aero matters at speeds as low as 10mph. It matters less than at high speeds but when distances are long those small differences add up.
Heine's experimental design is fatally flawed. There are 4 trials of a 15 second run-down test for each width. Given the small effect sizes you'd expect from differences in drag for that duration, there is no way this 'experiment' could detect anything from a power analysis perspective. The rough section is done on a rumble strip, which is also not representative of a typical gravel section. It's all GIGO (garbage in, garbage out).

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Mr.Gib
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by Mr.Gib

Heine has made some useful contributions to the cycling world, however this is not one of them. This is the same guy who insisted that a traditional steel, round tube frame was faster than those newfangled aero carbon jobs. I appreciate the nice tires he sells, and I am mildly amused by his take on issues such at this, but that is about as much as I can get worked up. He just isn't a serious voice in the world of cycling tech. I get the feeling he'd like to see us all riding in tweed wool button jackets, matching knickers, and handlebar mustaches.
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OnTheRivet
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by OnTheRivet

Mr.Gib wrote:
Thu Jan 12, 2023 12:25 am
Heine has made some useful contributions to the cycling world, however this is not one of them. This is the same guy who insisted that a traditional steel, round tube frame was faster than those newfangled aero carbon jobs. I appreciate the nice tires he sells, and I am mildly amused by his take on issues such at this, but that is about as much as I can get worked up. He just isn't a serious voice in the world of cycling tech. I get the feeling he'd like to see us all riding in tweed wool button jackets, matching knickers, and handlebar mustaches.
Jan is ridiculous sometimes but he's no Grant Peterson.

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