Wildwood 

https://www.cyclingnews.com/news/kris...paris-roubaix/

Alexander Kristoff, "I took a big risk on the tubeless wheels that I've been using the last weeks".

3 punctures before switching wheels.

maartendc

I read the same article. Strange, since I thought most of the benefit of tubeless was supposed to be self-sealing of small punctures?

In any case, you cannot draw meaningful information from this, because none of us ride 54 km of cobbles on a weekly basis.

Just as interesting to me were the mechanical difficulties of Sep Vanmarcke, who was stuck in his smallest sprocket in the rear for the last 40k of the race, costing him a lot of energy. This just after Peter Sagan had a similar mechanical issue with the rear derailleur at E3 Harelbeke. I am starting to see a trend with the reliability of electronic groupsets for the pros here, at least on the cobbled classics. Are electronic groupsets perhaps not designed to be vibrated around so much? Although, again, perhaps not a meaningful issue for the recreational cyclist.

jadocs

Little unclear as to what tubeless had to do with getting punctures. Is the article stating that he would not have punctured if riding a different tire/wheel combo?

maartendc

Exactly, that is what Kristoff claims, from the article:

I don't know why he thinks he would not have punctured 3 times otherwise. It is not uncommon, just bad luck usually.

jadocs

I read that......So he is claiming that he would not have punctured had he not been running tubeless.

So I'll ask, what does a tubeless specific puncture look like? because I see no mention of anything to indicate that he would not have punctured running a different combo....

Edit: I see you and I are seeing things the same way.

WhyFi

Homeboy rode 25s on cobbles. I think that pretty much ends the conversation.

Zaskar

I wonder if he's using the term "puncture" as a catch-all for "flat" - because, yeah... anything that would puncture a tubeless tire enough to cause it to lose noticeable PSI or totally flat, would absolutely flat a "regular" tire.

Perhaps the hard hits were burping the tire - losing big chunks of pressure with each burp. A tube obviously won't burp... it'll pinch flat.

CliffordK

My experience with riding in Rome was that in some cases, cobbles are good at hiding glass. But, that was long before tubeless bicycle tires were dreamt up. And, unfortunately, my sewups at the time weren't very puncture resistant.

Otherwise, cobbles weren't especially bad on my sewups.

Many years later, last fall, my tubeless experiment (Schwalbe Pro One) tubeless was cut short by hitting a rock (may have bottomed out), and tearing a hole in the Schwalbe Pro One.

The tire carcass was rideable with a tube (put in a dollar boot, but don't know if that was necessary). Can't say if it would have pinch flatted. I probably was slightly low on pressure. The hole was such that there was too much flex, and it would seal with the sealant down, but would leak again as soon as I started riding, and everything started flexing and opening the hole up again. But, it was fine with a tube + boot.

Hard to say about Alexander Kristoff. 3 flats in 100 miles? Obviously a failure in one form or another. Tubeless? His riding? Bad luck? Or, something with his tire choice?

TIRE PRESSURE? TIRE SIZE?

My flaw may well have been using too narrow of tubeless tires at too low of a pressure.

RedBullFiXX

Blaming tubeless tires as the cause of flats, but running Vittoria Corsa TLR on Cobbles... ok

burnthesheep

Pros don't run clinchers. They still run tubs. They run tubs for one reason so you can ride a flat until a service vehicle gets you a spare. You can't ride a flat clincher at all.

So, the tubs don't really "pinch flat" either like a clincher does. You don't have an inner tube to pinch/snakebite. It's integral.

Realistically, tubs and tubeless have the best racing failure modes for pros. I give the edge to tubs because you can't burp a tub.

ttusomeone

Two thoughts on this. 1) he says "punctures" but I wonder if he was burping the tire. Given the cobbles, I could see where someone his size, hitting a cobble at that speed, would pop a bead loss from the rim and cause a "flat". 2) with Sep, I'm assuming his Di2 wire came unplugged from either his RD or brifter. I saw a report that said it was the result of a crash, so I guess it could have went into crash mode and he wasn't able to get it out. Regardless, I wonder why (or if) teams don't superglue the cables in place for their top rider? It seems like even if it costs you one groupset, that's a small price to pay to not have your leader out of the race due to a mechanical like that.

Seattle Forrest

I don't know if that's what happened in this case or not, but for sure this is the truth.

cycledogg

It was said that Vanmarcke was involved in a crash, braking and or putting the RD in crash reset mode. The team car had trouble getting up to Vanmarcke to reset his RD. Still, electronic groups seem unreliable especially for classics. https://www.velonews.com/2019/04/new...-finale_492678

HTupolev

Tubulars can either use inner tubes in the same way that tubed clinchers do, or use sealed tubeless casing in the same way that tubeless clinchers do. In either case, pinch flats can happen in the same way as with clinchers: the tube can be pinched, or in extreme hits, the tire can be pinched. Pinch flats happen much less with tubulars because the tire is resting on a smoother rim profile, the force isn't concentrated as badly as it is on clincher rims.

79pmooney

I've pinch-flatted tubulars including a high-end silk in a race (on RR tracks). I also dented both rims in another race also on RR tracks at full speed a mile from the finish and didn't damage either tire. Had to pull out both rims with a puller. Twice I bottomed out on bottomless snow country potholes in deep puddles with loaded LowRiders and rode those wheels home with 1" deep dents, no flat. So, like HTupolev says, it can happen, but it happens far less frequently than clinchers.

Ben

TimothyH

And blame the wheels.


-Tim-

JohnJ80

Here's a great article on what it took to get carbon wheels working for riding the cobbles. Two big things - tires of proper width and proper inflation made a big difference. I would guess this was a big part of it maybe most of it presuming the "engine" was up to speed.

https://blog.silca.cc/road-to-roubai...lete-story-1-0

DrIsotope

Not just 25s, but Corsa Speeds, no less. 225g, and 1.7mm at the center of the tread, the thinnest tire the Rolling Resistance guy has ever tested. But sure, yeah, blame the fact that the tires were tubeless. Did he really think he needed the lowest rolling resistance tire on the market to ride over a bunch of loosely glued-together rocks?

pickettt

I can say with confidence that there is nothing that will PUNCTURE a tubeless tire that won't puncture a tubed tire as well.

79pmooney

"Puncture" here means only that this racer lost air in his tire and needed a wheel change. (To a racer, tire issues are "punctures". The rest of the bike issues are "mechanicals". He never did the research as to the exact cause nor did he care. (And I am guessing this came from a post-race interview. He just rode the most brutal 7 hour race on the planet.) I highly suspect he "burbed" his tires. Given how bad the cobbled road surface was in the (3) 5 star sections and that he was riding those cobbles in a field and may well not have had a good view of the them (and that he was riding over those cobbles at 25 mph), is anyone surprised? Given the course, my thought was "what were they thinking when they chose to go tubeless?" I could see putting some of his teammates on tubeless for the advertising, then giving Kristoff good tubulars with the logos blacked out. That's been done for decades.

Ben

JohnJ80

I believe Phillipe Gilbert rode a Di2 equipped bike to victory in Paris-Roubaix. And Quickstep, which has been powerful in the classics, has Di2 as the default for their bikes. Reliability is well understood with electronic drive trains at this point.

TimothyH

Yet manufacturers, retailers and countless bikeforum members claim that tubless tires are "Immune to punctures."


-Tim-

JohnJ80

Yeah, that's hyperbole for sure but they are better just because you don't get tube pinch flats anymore.

Pretty sure that the reason for all of the problems in question where bad tire choice in terms of size and construction and I'd also put a fair bit on it that the inflation was wrong , or at least off, too.

WhyFi

I don't think that I've ever seen that claimed; if it has been claimed, it's by a very small, and very dumb, group of people - certainly not "countless" members.

WhyFi

Such an unbelievably dumb decision on his/their part. I really wonder what Vittoria will have to say as a response.