No, it's the table under that that shows that the lower RR is from the widest tyre at recommended pressure. Ie from a rolling resistance point of view we should all be on fatbikes at 15psi if they made a GP5000 (or Corsa Speed TT) in 100mm width....

This was the 'revelation' for me where I knew that running wider tyres meant you can run lower pressures for comfort, and current thinking is that was much less of a penalty than previously thought (I mean 5+ years ago). I'm from the old school of racing XC mtb in the 1990s where we thought fast was a 1.6 Panracer FireXC at 80psi. Hurts my head to think we're not using tyres close to that on road at lower pressure now and they roll better than the 21mm at 120psi I was using for my first ironman.

Not sure, I follow:
Inner TubeNone (20 ml sealant)Measured Width25 mm (un-round)Rolling Resistance



Ultra High Air Pressure
(120 psi / 8.3 bar)9.6 Watts
CRR: 0.00288Rolling Resistance



Extra High Air Pressure
(100 psi / 6.9 bar)10.3 Watts
CRR: 0.00309Rolling Resistance



High Air Pressure
(80 psi / 5.5 bar)Members OnlyRolling Resistance



Medium Air Pressure
(60 psi / 4.1 bar)Members Only
I can't see the 60 and 80 psi as I am not a member, but are you saying it trends up, down from 120 to 100 psi and then goes down at 60-80 psi?

No. I am referring to the data in Continental Grand Prix 5000 S TR 25, 28, 30, 32 mm Comparison (bicyclerollingresistance.com) second table/graph in the rolling resistance section. I don't think that's paywalled, but if it is, then can I really respectfully suggest that as this is a topic of interest for you (vis this thread) then $5 for a months access would be well worthwhile.

Duncan74 wrote:

No, it's the table under that that shows that the lower RR is from the widest tyre at recommended pressure. Ie from a rolling resistance point of view we should all be on fatbikes at 15psi if they made a GP5000 (or Corsa Speed TT) in 100mm width....

Ah, I think it's just a wording issue.

You wrote this, "wider tyres with the appropriate lower pressure roll better than wider tyres at the recommended pressure."

When I think you mean this, "If GP5000S TRs of all widths are set to their recommended pressure, they'll get faster (at Crr) the wider they get."

Which I think is expected.


For that chart it was less than a Watt difference between the 25mm and 32mm. So not a lot at all. Though this is still smooth roller. Again, real world could be very different. And aero is a whole other thing. I'm on the wide bandwagon, but you won't see 32mm tires on my TT bike.

Have you ridden those tires in any of those widths, and if so, did you ride them at the 'recommended' pressures?

With the exception of not having ridden the 30mm, I have ridden them all, and I have ridden them at both the 'recommended' pressures and what I consider to be acceptable pressures for all-round daily riding (it's a few psi lower than 'recommended').

I weigh in around 180lbs, and for daily riding I'd run the 25s at 65F/70R, and if I were to extrapolate from the chart, that should result in a CRR of ~ 11.5w average. The 28s, at 60F/65R, ~11w average, and the 32s, at 53F/58R, ~10.4w average.

Those numbers are close enough that for daily riding, the clear winner is the 32mm. But, when factoring in aerodynamics, it gets a bit muddy, the choice isn't so clear. My TT race wheels are HEDs with a 25mm width at the brake track. From a drag perspective, the 25mm is the best choice, and there's no way that the 1 w savings from the 32mm tires would make up for the increased drag. Paired with different wheels, designed for much wider tires, and the results may differ, of course.

Ahh got you, yeah I see what you mean. FWIW, GCN did some bro science on the overall performance (i.e. CRR/CDA penalty) on a real road course. Again, bro science, n=1, whatever...but they found the ~28 mm to be the sweet spot for road bikes.

I've ridden the 28 but would normally ride slightly higher pressure than 'recommended'. In part due to being 85kg and my road bike isn't the lightest (synapse), in part I'm on a journey to lower pressures on road. That said, I have run at the recommended pressures too and at the ones you are saying, mainly post puncture but for several hundred KM. In fairness for me 70s get noticeably bouncy on climbs for me.

Conti is a rubber manufacturer that happens to turn that rubber into all sorts of tires, conveyor belting, hydraulic hoses etc. For reference, they mention "Bicycle" once in their 2022 earnings report, and "Mining" 15 times.

In 2022 the "automotive" GBU made up 46% of their sales. That does not include tires, which is its own GBU (35% of sales).

All that said, I believe slowman is on the right track regarding Conti focusing on compounds vs Vittoria on the tire as a system.

I love me some Conti tires, but all my mountain bikes run Vittoria tires. Once my 5000STRs in 28 mounted to HED Vanquishes wear out, I will be back on the vittoria train. Just so happened my Pirellis really needed replacing and the conti is what I could get.

I will be running corsa pros, I have a set of old corsa speeds that despite everyone saying are frail wore well and never flatted on me.

I can give up 6 watts and reduce my flat risk, that is easy math for me.

WRT tire/rim interactions, wasn't that the pitch from HED with the vanquishes, they are tire agnostic when it comes to stall angle.

Lastly, big props to everyone here that is smart enough to think of it as a wheel, tire and frame system. I suspect that is why Vittoria did the new tires in 24s. Still plenty of bikes out there that cannot clear the newer wide rim wide tire combos.

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Also love Conti, but I've always felt there's a (good) feel to Vittoria 320TPI cotton that no other tire has. Could be sheer bias and I'd fail a blind test. And I think the benefit of that feel is lessened by today's lower tire pressures. 28mm @65PSI Contis ride great. But I still swear I can feel it.

I've never ridden a Turbo Cotton, but I think that has a cult following as well.

i kind of think the opposite. the more you let a tire bounce, the more that sidewall is doing its thing. like you maybe that's all in my brain. but then again i have a lizard brain, so there's an instinct there not to be ignored. lizards have prevailed for a long time. don't underestimate that brain.

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Dan Empfield
aka Slowman

I think I pretty much get to the same place, but via a different route. It's not so much that Conti (and the other more diversified companies) don't prioritize sidewall construction, it's that they have very little interest in sidewall construction methods that aren't germane to the other product lines they offer. This is also true of their tread compounding, which I am given to understand is largely as good as it is for bicycles due to the large investments the company has made in automotive compounds that roll well, driven by EV development trends. This trend definitely continues, and it's unlikely we won't also continue to see improvements in bicycle tire compounds as a result.
Cotton sidewalls are awesome for bike tires but they're just not at all useful for much of anything else, so no one but a bike-specific company is going to dump money into that well. The question is, how much farther can a company like Vittoria push cotton sidewall performance? Now that they have figured out how to make tubeless cotton/latex clincher casings, where do they go from there? It seems unlikely they have the resources to keep up with the automotive companies in terms of compound R&D, and it seems equally unlikely that lightning will strike again, as it appears to have done their investment in graphene production. Especially given their VC majority investor, and the belt tightening that is omnipresent in the bike industry as well as the VC world.

FWIW, The purchase of Dugast by Vittoria? I'm much less sanguine about it than you are. They just shuttered the < 2 year old Dugast facility in the Netherlands, and they're moving all production to Thailand. Of which very little appears to be planned. According to the reportage in the Dutch press, Vittoria is going to discontinue all Dugast products save the "Vittoria A Dugast Series cyclocross product line", and it remains to be seen what exactly that is. It seems incredibly unlikely that they'll continue to offer the repair and customization services that contributed greatly to their near total dominance of the pro CX scene in Europe. Hell, I doubt that's even possible now that they have laid off everyone who did that work for them. Richard Nieuwhuis is also out, truly signaling the end of an era.

I wish I could believe that this acquisition was about "cycling...in your blood and bones"... heck, maybe it even was at the time it happened. Right now, though, it really appears to be leaning much more towards eliminating some niche competition, and commodifying the brand name. Vittoria never could figure out how to make cx tires that people actually wanted, maybe it was just easier to get rid of the ones that people did want.

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
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One company's BU can be bigger than another company in it's entirety. Conti is a huge company, so of course their tire business is relatively tiny. But their business is likely still bigger than Vittoria. There's no reason the team developing bicycle tires at Conti would be less worse in any way than the team at Vittoria.

The "developed as a system" vs "developed as a compound" is just philosophical hand-waving. It doesn't matter if in the end Conti have a better system. S TR is faster and less puncture prone prone than Pro Corsa. For most types of racing, these are the top considerations.

Which is too bad because I hate the feel of the GP5k tires! On my road bike I've switched to supple tires from Vittoria, Michelin, and now Tufo. When I first switched from GP5k to Michelin Power Cup, I kept stopping because I though I had a flat. There's no going back after feeling that buttery goodness.

But for racing, the S TR and TT TR are king and will stay on my TT bike.

. S TR is faster and less puncture prone prone than Pro Corsa.

Bikerolling resistance seems to score the puncture resistance of the 26 mm at 43 vs the contis 25 mm at 36. Crr tests indicate the two tires are within a 1 W of each other, how do you conclude the above?

It seems as plenty of WT teams will be riding the Corsa Pros, FWIW.

I have the contis S TR and really like them but I am definitely giving the Corsa Pros a chance.

I'm almost as heavy and have run the 28s (measured out to 30 on my wheels) as low as 55F/60R, and at those pressures they barely begin to feel too soft. Almost everyone I've spoken with about their journey into tubeless over-inflates their tires, afraid to make the move to lower pressures.

A tip for settling on pressures for daily riding: with your floor pump handy, start with your normal pressure(s) and let out just a tad. Ride around the block and see how it feels. Let out a bit more, see how that feels. Lather, rinse, repeat, until you get to a point that is clearly too low for your liking. Check to see what the pressure is at that point, then add 1 psi back in and Bob's your uncle.

I'm reasonably certain of two things. One, the end result will be a pressure that is lower, maybe far lower, than you were running previously, and two, given a few miles of riding to adjust, you'll come to love the lower pressure. It seems that one reason some people say that tubeless isn't for them is that they never try the lower pressures that are available.

Sometimes you just have to jump, and the net will appear.

Any luck testing these?

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DFRU - Detta Family Racing Unit...the kids like it and we all get out and after it...gotta keep the fam involved!

He has a post up today with the track version testing results. It mentions the Speed 24 and 26 Road TLR testing is done and results will be up soon.

I did see that but thanks!!

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DFRU - Detta Family Racing Unit...the kids like it and we all get out and after it...gotta keep the fam involved!

Data here :)

https://www.aero-coach.co.uk/...ling-resistance-data

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AeroCoach UK
http://www.aero-coach.co.uk

Well, that's a pretty quick tire...goodness.

Is it REALLY a little more flat protection? Do we care?

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DFRU - Detta Family Racing Unit...the kids like it and we all get out and after it...gotta keep the fam involved!

Seems impossible given the Crr results, but easy thing to claim given it is hard to refute.

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Dimond Bikes Superfan

Do you believe someone would get sub .002 on a good road or is that on rollers ?

No, you won't touch 0.002 on a road. The data represents an amazing/perfect track surface really - it's not the roller data but a conversion to an ideal track scenario (so that we can compare everything from track tyres to road tyres in an equal scenario, and it allows us to be really specific with our data inputs for aero testing round velodromes).

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AeroCoach UK
http://www.aero-coach.co.uk

I bought a few tires after you mentioned they were faster. I have tubeless compatible wheels but have just stuck with latex as Michelin Power TT have always been my race tire of choice. Was thinking of making the swap for these though. Do you have any thoughts on running these latex vs tubeless and whether certain sealants like Silca's might leak from them?

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
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These days I personally run latex tubes for all races. Your overall performance will improve by being able to swap tyres out depending on conditions etc. rather than sticking with one tyre setup on race day because de-tubelessing a wheel is a stress no one wants!

IF the new Corsa Pro Speed are amazing in other aspects - puncture resistance, wet grip etc. then there'd be an argument for leaving them on for everything and setting them up tubeless, but I think the ability to quickly swap out to something like GP5000TT for bad surface, Michelin PTT for wet grip, Veloflex Record 25mm clincher for ultimate speed means that latex tubes are a more versatile solution.

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AeroCoach UK
http://www.aero-coach.co.uk

Is there a latex tube brand/model you would recommend?