Road tubeless fails @ Paris Roubaix?

Just reading about Kristoff’s adventures with road tubeless @ Paris Roubaix. He seems to say road tubeless contributed to his day’s problems by saying he made a mistake in selecting the tire/rim combo that he did.

I’m not quite sure I understand how tubeless specifically is to blame in this instance. He got punctures. I’m not 100% geeked out on Paris Roubaix but it seems like punctures are fairly common there, correct? :wink: How is tubeless to blame?

While I’m not a big fan of road tubeless in general, Paris Roubaix, the spring classics, etc would be venues where road tubeless makes sense. If not there then where…

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He had a bunch of punctures even before the major cobbles started. There could be several different factors at play. I think he was running 25mm Vittorias with their new graphene construction. Maybe a larger tire, different pressure or different brand would have helped?

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25mm was a stupid choice. It would have been a bad choice whether he had been running tubeless or tubulars. Might just be fine when doing the recon as you can pick your lines, but in the race there’s much less chance to pick the line you want so you’re much more likely to hit holes

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Yeah, that’s what I wonder as well. Maybe not the right tire/rim combo.

For me, I would want a 28mm tire instead of a 25mm but I understand Kristoff’s choice! Those campy bora rims, IIRC, are on the order of 25.5MM - 26.5MM wide. So a 28mm tire is going to violate the Rule of 105 in spades. You’ll get a little on the cobbles but lose a LOT in the crosswinds.

Agree that 25mm doesn’t seem a wise choice. And specifically with tubeless, the higher pressures required for 25mm over 28mm means that sealant is less likely to do its job.

Not if you consider the rim profile he was using. Rule of 105! :wink: Cross wind drag decrement >> rolling resistance gain due to 28s on those rims.

Although in this case if additional tire volume would have provided additional puncture protection would have made a material difference! Also, the tally of riders running 28s in the spring classics seems to indicate that a.) Tour riders don’t know about the Rule of 105, b.) Tour riders do know about the Rule of 105 but don’t think it makes too big a difference.

Do we know what the actual measured size of the tyre was on these rims? My guess is that they’d be getting on for 28mm. My understanding is that the quoted tyre side is based on a narrower internal width that the Boras.


No. But given the campy 19mm inside width spec, photo #1, and photo #2, we can be fairly sure that the 25s would measure about 28.5mm? So, yikes, he was already violating the rule of 105. Why not go with the 28s, then? Maybe the frame didn’t fit a 28mm tire.

Either way, Kristoff spent a lot of time riding around on this setup. Both training and racing. So…

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Vittoria tires scare me to death. Thinking about them tubeless, wow. Just no.

Corasas (even with the G+), while they feel amazing to ride are about as durable as just running a latex tube on the rim. Rubinos are like riding two latex tubes.

The sidewalls on these tires are what is the scariest. I know the suppleness of the design is what makes, especially the Corsa, ride so well… but thinking about running them tubeless…no way.


My thoughts were that it wasn’t necessarily the punctures that ruined his race but the fact that you can’t continue riding on a punctured tubeless tyre. Puncture a tub and you can ride on a bit until the team car arrives for a wheel change.


Nice little graph.

28c tyres would be massive on those rims. 28c are the go-to size for tubulars (which are true to size) at PR although there were reports of some 30c this year.

My thoughts are that tubular tyres are still more resistant to pinch flats than tubeless due to the cushioning effect that you get from the base tape and the lack of small radius edges that can trap the sidewall.

Tubular tyres have very exposed sidewalls that, in a pinch flat situation, get trapped between the ground and the hook. Not as easily pinched as a tube, but still possible, especially with quite delicate tyres like the Corsa Speed G+.


Can you explain the rule of 105? I am new to cycling so not really familiar with these type of things


We also don’t know what tire pressure he was running. 25mm tires don’t give a lot of opportunity to compress before hitting a rim, and risking pinch flats. So even with tubeless, would need to run high pressures on cobbles.

Seems like a wider rim, with 28s would have been the choice if he wanted to go tubeless.

If the outside width of a deep section rim is not 105% the actual width of the tire mounted on that rim, the tire/rim combo is aerodynamically compromised at yaw angles in the lower to mid teens. Of course, depending on velocity, but it can amount to 5W per wheel. So that’s a material difference if you expect those sorts of cross winds.

Here is some data taken from a Firecrest 404 (which, btw, has a cross sectional width very similar to the rims Kristoff was using!) showing how drag interacts with yaw angle depending on the actual width of the tire. Here, the 25mm GP4k tire width is modulated just by inflation pressure…but there is a curve for a 23mm GP4k as well.

This may be why Kristoff elected to go with 25mm tires instead of 28mm.

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Thanks! Not going to lie, had to read it twice to make sure I got it haha

While this is a good set of information you can’t take these measurements as gospel. Different tires always measure differently, even the same brand/model tire can vary by a few mm here and there. Also, the reason you’d ride a 28 in Paris-Roubaix as opposed to a 25 is not to do with aerodynamics at all. If you save 30 seconds over an hour with narrow tires but you get flats because you didn’t run a wider tire then you lose way more than 30 seconds. Not to mention a wider tire is faster and more comfortable on the cobbles.

Interesting titbit in the Cycling Tips podcast saying that with the wind from the North, you find that the race tends to be won on the roads rather than the cobbles. Maybe if you think you can win it if everything goes in your favour you’re prepared to optimise for asphalt and hope that you get lucky on the cobbles?
I find that unlikely - I reckon Kristoff just stuck with what he knew because they had been good on all the other cobbles.

I think in the Classics, the 105% rule to worry about is fact you have about a 105% chance of losing the race if you get a flat in the later part of the race.

Sure, an ill timed flat can spell doom in almost every bike race but in the cobbled classics, the odds of flatting are so high AND the odds of flatting are highest when a team car is unlikely to be nearby thus increasing the risk. So, avoiding flats needs to be goal #1 and let aerodynamics take a distant second.


So you think Kristoff’s number one goal in selecting 25mm tires over 28mm tire was to avoid flats?

I’m skeptical…but do go on. How does that tire selection help avoid flats?

Not at all - he screwed up by picking tires that were prone to flats. 28’s would have been a better choice, heck with any extra aero drag. It sounds like a different brand might have helped too.

For a puncture type flat like a thorn or glass, tire size admittedly doesn’t matter much but bigger tires are more resistant to pinch flats or flats otherwise caused by slamming into things like holes are rocks.

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