In most TTs you won't need to ride on the shoulder, which is where all the punctury stuff lives.

I thought the discussion of tires and vibration losses (energy converted to rider vibration) was the most interesting. We were kicking this around on BikeTechReview about ... 15 years ago? Bigham is working on it, doing tests, and trying to nail down the variables. Good stuff.

I can't remember riding on the shoulder at any triathlon in my last 10 years of racing either.

I'd always race the fastest tires I could find if I could ride in the lane. Cars keep that part of the road swept pretty well.

I can't remember not riding on the shoulder of any triathlon I've done.

I think for most Triathletes, the best option is probably the "standard" GP5000 Tubeless. 2-3w total Crr loss if probably not worth the potential for punctures going with a thinner tire.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

In every TT I've ever done, minus Moriarty, where the course actually had a shoulder (or bike lane), racers were required to use the shoulder except when overtaking another racer. At Moriarty, if I hear traffic coming up from behind, I'm very likely to move to the shoulder as a precaution.

I rode on the shoulder at Moriarty once... the year the rest of it had just been chipsealed. Never otherwise.

When they tell me to ride on the shoulder, I ride close to it. The white line is usually fast and clear of debris.

I was under the impression that people were required to use the shoulder (as a slow lane at least) at triathlons due to the density of participants, traffic, and frequent passing, but maybe I'm wrong.

Likely a USA vs. Europe and most of the rest of the world difference. US races almost never seem to have the backing to get roads closed.

I wouldn't but I can only think that if you flat in an ITT, it's a relatively short race and not possibly something you're hanging your whole season on. However, if you're only doing one Ironman a year, you might want to lose a little speed for a little more reliability and comfort. That said, over here in the UK where TT'ing is huge, many of us are moving on to 28mm width (at least on the rear) and even run thin track tyres or tubs on the really big occasions/speed fests.

They lied. I believe they've launched the Corsa Speed in a new version today in 24, 26 and 28mm widths.

in fact they have, as i reported this morning on the front page. this tire becomes the prime competitor to the conti 5000 TT TR, which has been the fave of pro triathletes, once they could get hold of it. i find this quote from BRR on this conti tire telling: "We've tested the 28-622 of the Grand Prix 5000 TT TR as the 28 mm size quickly becomes the preferred tire size in the tubeless road bike category. It's also available in the 25-622 size for those who still like slightly smaller tires."

the world is moving to 28mm and this new Pro Speed, having (presumably) cured the sidewall leakdown annoyance of cotton tires, will i predict penetrate the pro transition racks in IM and PTO racing.

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Dan Empfield
aka Slowman

"Two months later we saw this tire on Vingegaard’s TT bike during Stage 16 of the Tour, so we knew it was coming"

Just connecting these two statements : he rode 26mm IIRC. I wonder why. Did the aero outweigh the CRR ? If so what it the tire or the tire/wheel combo ? Is this a long distance tri tire ? so many questions

i don't know but here are 2 possible options:

1. his advisors did in fact feel, as you seem to, that 26mm was faster.
2. the 28mm tire was not yet available last july.

i don't like to offer advice on someone else's business (unless that person seeks it) but you have a lot more reputational blowback riding on this than i do (as my commercial intersection with this question is in my rearview mirror). there are experts - and i mean that literally, not in quotes - who used to be here but who are not hear any longer. it's a minus to us all. but i note that those experts were often wrong in their prognostications and i can't help but think that blew back on their ability to advise people on tech and product. some of these folks were very clearly wrong on tubeless and disc brake. a different collection of these experts are - i believe - going to be found out as charlatans re their dismissal of HR in favor of the all-important worship of power (but that's another topic). in the present case, it's your job to advise teams, yes? test and advise. it's bad to be wrong on this.

as we know - as you know - 28mm rolls faster than 25mm. so the question is, are the aero disadvantages so profound as to overcome the rolling advantage, and whatever the damping advantage (which is both a mechanical and biomechanical question)? i'll certainly give you this: you can't just slap a 28mm tire where a 25mm tire used to be. it's a system.

but this is the very same discussion we had on disc brakes, esp on tri bikes. you can't just slap on a disc brake and proclaim the tech a failure because it doesn't calc out. more and more new TT/tri bikes are coming optimized for 28mm, as are certain important aero wheels coming out.

that said, i don't know the answer to your question. in fact, the wheels vingegaard did ride would've very easily accommodated 28mm tires.

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Dan Empfield
aka Slowman

I don't know how much faster 26 is from an aero perspective
I don't know how much faster 28 is from a CRR perspective. I am going to test that soon, but my gut tells me an optimal 26 vs optimal 28 will be damn close.

I suspect the 26 is overall faster but that is a guess. That is probably heavily biased by the fact that smart people, that test, made the decision so the chances are there is something there

There was a pretty good podcast recently with JP Ballard of swissSide where they went through all the bikes at TDU. He made some really interesting statements. Tire width was one. His opinion on hookless was another. Fascinating stuff. Not sure you are a podcast guy.

https://escapecollective.com/...allard-of-swissside/



We need to find a way to get them back and keep them

well, we don't boot them. even the most notoriously caustic have almost always been welcome here. i don't know. but when you're just famously, notoriously wrong, it's hard to come back to the scene of the crime. one can't discount that.

i asked the folks at vittoria for confirmation on when the 28mm version was available, and whether that could've been an option at the TdF. i'll report back the answer.

look, swissside and probably DT swiss, and probably shimano, will all end up in one place on this. zipp, enve, cadex, they'll probably end up in another place. when i was on the marginal gains podcast it seemed to me (unless i misheard) that josh said that you have to get over 30mm for the air drag to overcome the benefit of rolling resistance of the larger tire. but he might've wanted to qualify that for use case. i don't know. we'd have to ask him.

there's an absolute place for questioning new tech. (i'm annoyingly against integrated stem/bars.) the skill is in knowing which new tech is good and which isn't ;-)

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Dan Empfield
aka Slowman

Whilst not relevant to this Vittoria story, I think it’s notable that given a full range of available widths and wheel choices that were not always restricted by sponsors, Dan Bigham opted for 25mm front, 28mm rear for the TT specialists at Ineos this past season. I’m not saying that’s the answer but given the expertise involved should be a pretty decent philosophical starting point for anyone’s thinking on this issue.

Lest we forget, he chose those tires to go with the specific wheels he was running, and for different wheels he very likely may have chosen something else altogether.

I am wondering if a 28 mm tire really needs a wider internal rim width. The 21mm seems to date back to the HED Jets, which I rode with 23mm tires probably about 8 to 10 years ago. Most 25mm tires look OK on a 21, but 28s start to take on that lollipop shape. Hunt and Reserve have started to move to wider rims, which probably means everything I own will soon be obsolete.

At some point it seems like internal rim width needs to scale with tire width. My guess is that it will be 28mm tires are the breakpoint for a 23-25mm internal rim and it scales from there for 30 and 32mm tires. Have you heard people in the industry talking about this?

Agreed; that podcast was awesome. It was very refreshing to me that he pulled no punches, while still saying it was "his opinion". His credentials pretty much speak for themselves. That was one listen that was pure gold and I can't wait until they release the long podcast with JP.

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Kiwami Racing Team

you're exactly right. what i've found is that a 5mm delta between internal bead width and nominal tire size works quite well. so, 23mm/28mm. 25mm/30mm or 32mm. the internal also pushes out the external. so, in vingegaard's case, his reserve wheels had a 22mm internal and a 30mm external, so he could've ridden either 26mm or 28mm in the tour TT last year (he rode 26mm) and he'd have had a pretty decent aero profile tire + rim. i have 2 road bikes and 2 sets of wheels for each bike (SRAM and shimano). my performance wheels are both 23mm internal bead width and 28mm tires. my beater, bad pavement, rideable dirt, go anywhere and not get a flat wheelsets are both 25mm internal bead width and 32mm tires.

as for whether anyone industry person has actually spoken about this repeatedly, eloquently, with perfect reasoning, obvious authority and tight, elegant prose, one person comes to mind ;-)

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Dan Empfield
aka Slowman

I'd normally agree with you on such issues but there is a fair bit of anecdata and evidence that is indicating that the width on the rear - aerodynamically speaking - doesn't make a meaningful difference but RR does so its 28mm all day long back there. As for the front, I would agree with you that's where the careful matching needs to take place but I'm yet to be convinced that 28mm on the front is the best option when all the factors are taken on balance.

I think perhaps quite a few people are making a mistake of assuming that CRR trumps CdA in all situations, especially considering it was only just recently that people accepted that in almost all situations CdA trumps weight. This is compounded by the fact that for a good many tires, such as the Speed G and the Conti 5000, the RR is for all intents and purposes equal when pressures are adjusted for real world conditions. Sure, you can get a 28mm Speed G to roll as fast as a 23mm, but it will be an unreasonably harsh ride, one that would be minimally acceptable for the rear but far too harsh for the front, IMO.

Agree.

I have some road testing queued up in Feb and I will try and compare "optimal" pressure on wider/narrower and see if the rider can even perceive the comfort difference.

I'd be curious to see what you find. I can tell you from personal experience that even on a road bike where I'm not resting on my forearms, over-inflating my 28mm 5000 S-TRs by 3-4 psi makes a huge difference in comfort. I can't imagine riding it 10-15 psi higher.