Hookless and updated ISO Standards - Thomas De Gendt Crash

[Lina]

No is the correct answer. Congratulations, though that was a number of posts and paragraphs of information to questions I didn't ask before we got there.
Zipp have the wheel in their possession and that is the determination of their engineers.
You don't agree they are able to make that assessment despite not examining the wheel yourself.
We are back to the central tenet of your argument being, Zipp are (very publicly) lying.

You don't get it. Yes Zipp is saying that how this case happened is "De Gendt hits something -> rim gets damaged -> tire comes off the rim because of the damage -> loss of control -> the crash happens". No one in this thread has said anything to challenge Zipp's interpretation of the events is something else. What is being challenged is if they got the order of events correct and it wasn't "Tire comes off the rim -> loss of control -> the crash happens -> during the crash the rim got damaged". I'm not claiming and I haven't heard anyone else claiming that they'd be able to even make that determination from the wheel itself without having high quality video of the crash. If you're a Zipp engineer and believe that the tire can't come off on its own then the only cause of events you'll come up given the evidence is that De Gendt hit something that destroyed the rim and that caused the crash. Is that correct? Well nobody knows because there isn't any actual proof that is how it happened.

[warthog101]

No is the correct answer. Congratulations, though that was a number of posts and paragraphs of information to questions I didn't ask before we got there.
Zipp have the wheel in their possession and that is the determination of their engineers.
You don't agree they are able to make that assessment despite not examining the wheel yourself.
We are back to the central tenet of your argument being, Zipp are (very publicly) lying.

You don't get it. Yes Zipp is saying that how this case happened is "De Gendt hits something -> rim gets damaged -> tire comes off the rim because of the damage -> loss of control -> the crash happens". No one in this thread has said anything to challenge Zipp's interpretation of the events is something else. What is being challenged is if they got the order of events correct and it wasn't "Tire comes off the rim -> loss of control -> the crash happens -> during the crash the rim got damaged". I'm not claiming and I haven't heard anyone else claiming that they'd be able to even make that determination from the wheel itself without having high quality video of the crash. If you're a Zipp engineer and believe that the tire can't come off on its own then the only cause of events you'll come up given the evidence is that De Gendt hit something that destroyed the rim and that caused the crash. Is that correct? Well nobody knows because there isn't any actual proof that is how it happened.

I disagree that Zipp are not saying rim damage caused the tyre to come off as per this yet again; "The engineers have reviewed the wheel in question and it was clearly a result of a significant impact. When you hit something hard enough to destroy the structure of a rim, the tyre is going to come off."
And again, the tyre was off before the crash.
They have the advantage of having examined the wheel. It is a very public lie if it is untrue.

[Jaisen]

Escape collective just released a podcast where they talk with Zipp directly about hookless.
https://escapecollective.com/question-t ... de-safety/

There is also a long article included.

[mikehhhhhhh]

Escape collective just released a podcast where they talk with Zipp directly about hookless.
https://escapecollective.com/question-t ... de-safety/

There is also a long article included.

Folk asked for transparency and Zipp have provided it to be fair.

It seemed like a fairly objective account, too. Fair play.

[Jaisen]

Escape collective just released a podcast where they talk with Zipp directly about hookless.
https://escapecollective.com/question-t ... de-safety/

There is also a long article included.

Folk asked for transparency and Zipp have provided it to be fair.

It seemed like a fairly objective account, too. Fair play.

Agreed, there were some really interesting stuff in there too. Zipp confirmed they tested tire retention to 1.5x, just like Cadex and Hunt do. Enve claims 1.8x, but either way all the manufacturers seem to be well above the ISO 1.1x multiplier. What's interesting is the Zipp guys also mentioned the variability in temperature, gauge accuracy, altitude, etc. can add up to a 1.35x influence, so when they test retention at 1.5x the margins of error that a user can make appear to be are well exceeded by the safety of the hookless system.

Zipp also confirmed that during impacts large enough to cause a rim failure their tests showed that the instantaneous increase in pressure is at most 4 psi. So when you hit that pothole you aren't suddenly going up 20 psi. Good to know.

I do find criticism with the double standard, one for consumers and one for pro teams, so hopefully they update their compatibility chart to fall in line with the latest ISO standards. Apparently they are having an internal discussion whether to change it or leave it the same.

Either way I applaud the overall transparency.

[MikeD]

I think it does. As I've said before, it's pretty typical in engineering design to design to a level of 1.2 to 1.5 above the operational standard. That gives you the safety margin. The only problem here is that Zipp is not stating the exact margin they design to. But their words imply a good safety factor as above.

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Not for safety critical items like boilers and pressure vessels.

"When it comes to the nitty-gritty numbers, for ASME BPVC Section VIII vibes, the go-to FoS is about 3.5 if your material can clearly show when it’s had enough (yield point). No clear yield point? You might be looking at a FoS of 4."

[Butcher]

I suspect once De Gendt says what happened, we will never know. I think he would know if he hit something so hard that it ruined the wheel, he would remember it. I'm certain he is not going to say anything that will be against the sponser.

With the failures that a tubeless can have, I still see no advantage of them. Just me.

[MikeD]

The fact is that De Gendt was using Vittoria Airliners, so it's impossible for the tire to get into the deeper channel. I have used tubeless Veloflex Corsa in combination with Zipp 303 and Vittoria Airliners, and it was even impossible to get the tire off without cutting it to pieces or the special Vittoria tools.

I couldn't get the tire in the deeper channel with my hands after deflating the tires. And since I didn't had the Vittoria tools there was no other option than cutting the Veloflex tires to replace them.

The way the Airliners work, they compress down to a small diameter cross section under inflation pressure, so they aren't providing any support to the tire. Only when the pressure drops do they expand. The question is, if there's a rapid decrease in pressure, do they expand fast enough to keep the tire on the bead seat?

[bobones]

With the failures that a tubeless can have, I still see no advantage of them. Just me.

Please don't conflate tubeless with hookless. Tubeless is just as safe as clinchers with tubes, if not safer.

[Butcher]

I'm comparing tubeless to tubular. I understand that it's old technology and some tubulars have come off, but with all the years they have been around, probably less than what tubeless has.

I also understand this is new technology and over time, they will resolve this. Either by saying, this is a stupid idea and this is better or just coming up with something completely different.

[Mr.Gib]

I suspect once De Gendt says what happened, we will never know. I think he would know if he hit something so hard that it ruined the wheel, he would remember it. I'm certain he is not going to say anything that will be against the sponser.

That's the elephant in the room. If De Gendt could possibly point to some event that might have occured prior to crash, and that might have been responsible for the tire blow-off, we would have heard it loud and proud. It would have been on the home page of Zipp.com day one. The guy is a pro's pro - he would never leave a sponsor twisting in the wind. Even his original tweet would have been "I hit a rock" not "did anybody see anything?" The silence speaks for itself.

[goodboyr]

I think it does. As I've said before, it's pretty typical in engineering design to design to a level of 1.2 to 1.5 above the operational standard. That gives you the safety margin. The only problem here is that Zipp is not stating the exact margin they design to. But their words imply a good safety factor as above.

Sent from my SM-S918W using Tapatalk

Not for safety critical items like boilers and pressure vessels.

"When it comes to the nitty-gritty numbers, for ASME BPVC Section VIII vibes, the go-to FoS is about 3.5 if your material can clearly show when it’s had enough (yield point). No clear yield point? You might be looking at a FoS of 4."

Sure. Structural safety margins are what I was thinking of. An exploding pressure vessel is a different beast.

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[toxin]

If it truly was the rim that failed first which led to the blowoff, that's almost more concerning than the hookless part. What the hell did he hit and how that he didn't come off from the impact but the rim still failed?

[mikehhhhhhh]

I'm certain he is not going to say anything that will be against the sponser.

Zipp don't sponsor Lotto Dstny

[EtoDemerzel]

I'm certain he is not going to say anything that will be against the sponser.

Zipp don't sponsor Lotto Dstny

Orbea's wheel brand Oquo is the "official" partner. This is contractual.
Zipp sponsors the team, obviously. Zipp sponsor through Dstny, so they can have Oquo as official partner, keeping Orbea happy.

Zipp sponsored teams 2024: