Open mold wide profile carbon wheels

[Zigmeister]

^ Yes, didn't Zipp use their "Tangent" tubulars, which of course are re-branded Vittoria Corsa Cx Evo 320tpi tubulars, with latex tubes?

[WMW]

Blowout of tire occurs when the heat is too high, raising the pressure inside the tube, and hence a blowout - which can often damage the sidewall of the rim because pressures were exceeded.

How high is the temperature in the tube going to get? 200F? If it is 80F outside, then if you started at 100 psi the pressure would rise to ~120 psi. That isn't enough to damage anything. That in combination with a Kevlar bead that gets softer at higher temperatures could result in the tire coming off if the cornering forces are just right, though. Even more likely if the tube and tire installation wasn't done right.

[Zigmeister]

Lennard Zinn has had a few articles where manufacturers responded to these topics regarding tubeless tires recently. Same idea regarding blowouts and where the failure point would be.

I thought Zipp found the sidewall would blowout of the tire, not the tube, don't recall if these were tubulars or clinchers now that I recall that video.

Will try to find a link.

[petepeterson]

ZIG: I assume WMW is talking about zipp clinchers. Tubular rims/tires do not fail from heat build up. Just about all good quality tubular tires use latex tubes. It's just not an issue with tubulars.

Here's a personal story: I had a set of Farsports Clinchers deform (not delam) at the brake track last summer. It was a hot day and I rode one of the more steep/technical descents in my neck of the woods and was maybe being lazy with the brakes. Plus I had the pads set up higher on the track than farsports recommends after having my tubular wheels on. Point being I was running challenge latex tubes and they were fine. The rim hook was hot enough to be pushed out a mm or so while the latex tube was fine. Just my own experience.

[kavitator]

All carbon rims can be delaminated - clincher and tubulars

Just at tubulars there is no risk of tire blow becouse tubular is glued on all surface and brake track on rim has just mission to braking

Clincher brake track has mission brake and hold tire in place - if walls on rim become soft (overheat epoxy resin) it wont hold tire in place.

some pictures:
http://kavitec.blogspot.com/2011/12/obr ... -1del.html

sorry for strange english

[kavitator]

There's two types of failures due to overheating:
-blowout of tire (and with that, often the sidewall)
-delamination of sidewall, which can create a 'blowout' since the tire can't hook onto a failed wall.

good post!

But if you leave bike on hot summer sun there is no blow out - i think there cant be so much pressure increase becouse of braking. Maby on very light rims (low profile) and heavy riders - i have one case with alu clincher 380g rim - rider blew his inner tube on steep descend and full braking- 84kg rider, 20% descend, summer weather

[petepeterson]

Never heard of that but i'm sure it's happened. Not saying you're wrong but you need to acknowledge the rate of failure gap between clinchers and tubular rims. Carbon tubular wheels are pretty sound established technology.

[Calnago]

Lots of pics around showing delaminated carbon clinchers. Anyone got a pic of a delaminated tubular, any brand?

[kulivontot]

I think part of the deal with carbon tubulars is that the air is not constrained in a sideways 'D' shape, meaning that as the pressure increases it applies force uniformly in all directions, making it have no real critical point of failure (the rim hook in clinchers case). Think of it this way: inflate a balloon in open space until it pops and the. Do the same with a balloon constrained inside a box. One is going to pop first.

[Calnago]

@kulivintot: that's not "part" of the deal with carbon tubulars, it's THE deal. It is well known and is the reason carbon clinchers are so problematic compared to tubulars. That's why I'd like to see some pics of a delaminated carbon tubular. I've never seen one. Because they don't share the same problem as carbon clinchers, aside from less than stellar braking that is.

[prendrefeu]

@Calnago - tubular rims delaminate on the gluing surface, often when the tire is removed. Anyway, Google Image search and you'll see results.

That said, we're going a bit off topic here. If you want to debate clinchers vs. tubulars there are other threads for that. I simply responded to an original contention that carbon clinchers are not able to take steep descents - and this is simply not true as a blanket statement.

Let's get back on topic!

[Calnago]

"Delaminating" on the gluing surface is completely different than blowing apart while riding. And it is more likely due to just ripping off the tire in one minute, which people claim to do roadside. It takes me a good 15 minutes to remove a properly glued tubular, exactly so I don't experience what you're describing.

I only asked to see a pic because someone stated that all carbon rims can delaminate and just want to make it clear that tubular carbon rims do not delaminate in a dangerous way like carbon clinchers do. And they do. This is not off topic... and I would argue that I for one would be leaving any carbon clinchers at home if I was taking off to the Alps for a few weeks. That's not to say you might be just fine using them, but don't say they are equally as safe as carbon tubulars or alloy rims. They aren't. Brake pads have gotten much better however.

[petepeterson]

Agreed. It may be off topic but I appreciate it when Internet misinformation is clarified.

[kavitator]

i saw some tubular carbones with wooble brake surface - not delaminated but it was clear that epoxy was in soft stage and brake surface get new shape.
and most damaged parts on rim is where spoke nipple is - some rims were pulled towards hub becouse of spoke tension

Proper brake pads are important

[splunk]

I recently ordered some and have some weights of the u45mm rim for everyone...

The 18h rim weighed in at 418g;
and the 24h rim at 469g.

The weights obviously surprised me as both are outside the tolerance of 450g +/- 15g specified on the webpage.