Tadej Pogacar’s Giro Crash: Final Nail in the Hookless Coffin?

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TobinHatesYou
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by TobinHatesYou

bikercr wrote:
Sun May 12, 2024 11:43 am
https://youtube.com/shorts/GFyC9RKmMM4? ... lDZRlZDOMW

Here's a video of DeGendt's hookless failure. Zipp claims he stuck an object in the road, but there's nothing visible on the video. And, no one else in front or behind him, in a tight pack, struck anything.

I obtained the video link from within DeGendt's own Twitter post on his crash.

We’ve analyzed the video before. There is clearly an object in the road. The screengrab below doesn’t show it that well, but if you scrub through frame by frame, you can see it pass by. De Gendt also explicitly says he hit something and there are broken up pieces of asphalt clearly visible on the other side of the median.
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apr46
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by apr46

I don't think there is an issue here. I also think that ill informed arguments against hookless have been construed by hyperbole and are being used to paint people who are cautious about hookless as hysterical.

Proponents of hookless will use other vehicles and their tire and rim systems has an example. They will say that "if you assume a perfect rim and perfectly inelastic tire bead, the hooks have no function retaining a tire that is inflated." This is true. But the tire rim interface seems often less than perfect for bikes for many reasons ranging from wanting lower weight tires to carbon rims, so the hook offers a type of interference fit, allowing for the system to avoid local failure via the bead moving out of place or the tire and / or rim not perfectly sealing. This is what hookless gives up.

When deflated the force exerted on the tire that pushes keeps the tire in place isnt there so there tire isn't held against the side of the rim. At this point the tire / rim interface is already not functioning. Hookless doesnt give up much of anything in this scenario. This is the also the scenario that caused Pogacar to crash.

Inserts should be able to keep the tire in place, hooked or hookless by holding the tire in place so that the tire rim interface continues to function. However, I personally will not run them until its clear that these inserts are safe and not transfering loads to the rim bed in ways that the rims are not designed to handle. It struck me that in the aftermath of the De Gent crash mentioned above, Zipp was unwilling to rule that out and even stated that the safety of inserts related to not damaging rims had never been validated by Vittoria.

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cleanneon98
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by cleanneon98

So now Pog slipped on his sealant? You mean if this was a hooked rim and he took a corner with a completely flat tire it wouldn't have come undone and spilled sealant right?

Nobody is going to take you or your "cause" seriously if you are making up nonsense to try and prove a point. It doesn't matter what your qualifications are at that point
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TobinHatesYou
Posts: 12902
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by TobinHatesYou

apr46 wrote:
Sun May 12, 2024 9:18 pm

Inserts should be able to keep the tire in place, hooked or hookless by holding the tire in place so that the tire rim interface continues to function. However, I personally will not run them until its clear that these inserts are safe and not transfering loads to the rim bed in ways that the rims are not designed to handle. It struck me that in the aftermath of the De Gent crash mentioned above, Zipp was unwilling to rule that out and even stated that the safety of inserts related to not damaging rims had never been validated by Vittoria.

You’ve parroted this weird claim by Zipp on Discord, and I’m still confused by it. At minimum these rim beds can handle 80psi by default and I would guess that most can easily handle double that. A foam liner is probably exerting a few psi at most on the rim bed at the point of ground contact and it’s acting as a safety barrier in case something pointy gets run over. In addition, all these rims are expected to be safe with pressurized butyl tubes.
Last edited by TobinHatesYou on Sun May 12, 2024 11:49 pm, edited 1 time in total.

apr46
Posts: 321
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by apr46

TobinHatesYou wrote:
Sun May 12, 2024 9:57 pm
apr46 wrote:
Sun May 12, 2024 9:18 pm

Inserts should be able to keep the tire in place, hooked or hookless by holding the tire in place so that the tire rim interface continues to function. However, I personally will not run them until its clear that these inserts are safe and not transfering loads to the rim bed in ways that the rims are not designed to handle. It struck me that in the aftermath of the De Gent crash mentioned above, Zipp was unwilling to rule that out and even stated that the safety of inserts related to not damaging rims had never been validated by Vittoria.

You’ve parroted this weird claim by Zipp on Discord, and I’m still confused by it. At minimum these rim beds can handle 80psi by default and I would guess that most can easily handle double that. A foam liner is probably exerting a few psi at most on the rim bed at the point of ground contact and it’s acting as a safety barrier in case something pointy gets run over. In addition, all these rims are expected to be safe with pressurized butyl tubes.
I dont think its that weird to think that eva foam liners would be different than pressurized air. After all volume change of a compressible gas will result in different forces than an impact to foam, especially with sealant involved which is functionally uncompressible and therefore needs to be displaced. Don't take this as me saying Zipp should not be scrutinized here, afterall their rims sure seem to have an issue that is not at prevalent on other rims.

I can accept my own limitations and admit that I dont know the answer here. It sure seems a lot more complicated than saying that the if air pressure doesnt result in forces that break a wheel, the elastic foam won't transfer force more directly to the rim bed. More than my ability to understand this it's more disturbing to me that no one seems to know when we are talking about a part of the bike that is safety critical.

apr46
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by apr46

cleanneon98 wrote:
Sun May 12, 2024 9:43 pm
So now Pog slipped on his sealant? You mean if this was a hooked rim and he took a corner with a completely flat tire it wouldn't have come undone and spilled sealant right?

Nobody is going to take you or your "cause" seriously if you are making up nonsense to try and prove a point. It doesn't matter what your qualifications are at that point
If this is directed at me. I am saying that likely regardless of hooked or hookless Pog faced a similar probability of crashing when riding a flat tire without an insert.

bikercr
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by bikercr

Several pro teams are running tubeless with inserts (and some with hooked bead wheels, I presume). A properly sized insert with a hooked bead rim create a very tight seal even when the tire is completely flat. You can get sealant leakage, but not the kind of gush clearly visible in the Pogacar video.

When i had my front sidewall puncture in a hard downhill 90 degree turn, leaning over to make the turn without braking, there was no tire separation and no sealant loss (except a slow trickle from the puncture). Even riding the flat 10 miles home, didn't lose any sealant.

It was incredibly hard to remove the tire. The insert really holds the tire bead in the bead channel. I'm running FFWD hooked carbon wheels. It took me an hour to get the tire off with special tools! That's why i didn't crash when the blowout happened.
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wheelbuilder
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by wheelbuilder

bikercr wrote:Several pro teams are running tubeless with inserts (and some with hooked bead wheels, I presume). A properly sized insert with a hooked bead rim create a very tight seal even when the tire is completely flat. You can get sealant leakage, but not the kind of gush clearly visible in the Pogacar video.

When i had my front sidewall puncture in a hard downhill 90 degree turn, leaning over to make the turn without braking, there was no tire separation and no sealant loss (except a slow trickle from the puncture). Even riding the flat 10 miles home, didn't lose any sealant.

It was incredibly hard to remove the tire. The insert really holds the tire bead in the bead channel. I'm running FFWD hooked carbon wheels. It took me an hour to get the tire off with special tools! That's why i didn't crash when the blowout happened.
Hey man. I don't know you at all, but I'm guessing we are probably around the same age, with possibly the same intense dedication to cycling, fitness, etc. We both have multiple decades of riding and racing experience too, and possibly a fair bit of wisdom and station in life.
You are going too far with this. We all read and appreciate your recounting of your descending event. You are technically accurate and a good narrative writer. I would just let this one go for now. Let's see if anything develops with UCI, etc. Take my advice if you can.
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TobinHatesYou
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by TobinHatesYou

apr46 wrote:
Sun May 12, 2024 10:36 pm

I dont think its that weird to think that eva foam liners would be different than pressurized air. After all volume change of a compressible gas will result in different forces than an impact to foam, especially with sealant involved which is functionally uncompressible and therefore needs to be displaced. Don't take this as me saying Zipp should not be scrutinized here, afterall their rims sure seem to have an issue that is not at prevalent on other rims.

I can accept my own limitations and admit that I dont know the answer here. It sure seems a lot more complicated than saying that the if air pressure doesnt result in forces that break a wheel, the elastic foam won't transfer force more directly to the rim bed. More than my ability to understand this it's more disturbing to me that no one seems to know when we are talking about a part of the bike that is safety critical.

I'm trying to think of a real-world scenario where the foam material would ever exert more than a few psi on the rim bed. If the tire is flat and you run over a sharp object, I'd still rather have the foam in place instead of having nothing to reduce the impact. If the tire is inflated, the Air Liner is already compressed to the diameter of Tootsie Roll and the tire is only going to deform to the point where it gets pinched by the edge of the rim.

Many of us have had nails/screws deflect off our rim beds and a piece of foam is never going to impact a rim like that.

apr46
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by apr46

TobinHatesYou wrote:
Mon May 13, 2024 12:06 am
apr46 wrote:
Sun May 12, 2024 10:36 pm

I dont think its that weird to think that eva foam liners would be different than pressurized air. After all volume change of a compressible gas will result in different forces than an impact to foam, especially with sealant involved which is functionally uncompressible and therefore needs to be displaced. Don't take this as me saying Zipp should not be scrutinized here, afterall their rims sure seem to have an issue that is not at prevalent on other rims.

I can accept my own limitations and admit that I dont know the answer here. It sure seems a lot more complicated than saying that the if air pressure doesnt result in forces that break a wheel, the elastic foam won't transfer force more directly to the rim bed. More than my ability to understand this it's more disturbing to me that no one seems to know when we are talking about a part of the bike that is safety critical.

I'm trying to think of a real-world scenario where the foam material would exert more than a few psi on the rim bed and can't. If the tire is flat and you run over a sharp object, I'd still rather have the foam in place instead of having nothing to reduce the impact. If the tire is inflated, the Air Liner is already compressed to the diameter of Tootsie Roll and the tire is only going to deform to the point where it gets pinched by the edge of the rim.
I think you are probably right to be honest, but if someone is selling me something they are telling me will improve my safety I want more than "this probably makes you safer." I also wouldnt be quite so dismissive of potential forces being transmitted, I dont understand how and over what area the force applied these foam insert would be spread. I would in most casual riding scenarios rather be compelled to stop than not given the potential consequences of a subsequent impact breaking my wheel.

Either way, Pog wasnt riding inserts, so sorry about the distraction. I just feel like safety isnt getting enough attention from bike companies and emotionally that makes me feel...both annoyed and sad at the state of things.
Last edited by apr46 on Mon May 13, 2024 4:15 am, edited 2 times in total.

bikercr
Posts: 75
Joined: Mon Sep 11, 2023 1:06 pm
Location: Massachusetts

by bikercr

wheelbuilder wrote:
Sun May 12, 2024 11:49 pm
bikercr wrote:Several pro teams are running tubeless with inserts (and some with hooked bead wheels, I presume). A properly sized insert with a hooked bead rim create a very tight seal even when the tire is completely flat. You can get sealant leakage, but not the kind of gush clearly visible in the Pogacar video.

When i had my front sidewall puncture in a hard downhill 90 degree turn, leaning over to make the turn without braking, there was no tire separation and no sealant loss (except a slow trickle from the puncture). Even riding the flat 10 miles home, didn't lose any sealant.

It was incredibly hard to remove the tire. The insert really holds the tire bead in the bead channel. I'm running FFWD hooked carbon wheels. It took me an hour to get the tire off with special tools! That's why i didn't crash when the blowout happened.
Hey man. I don't know you at all, but I'm guessing we are probably around the same age, with possibly the same intense dedication to cycling, fitness, etc. We both have multiple decades of riding and racing experience too, and possibly a fair bit of wisdom and station in life.
You are going too far with this. We all read and appreciate your recounting of your descending event. You are technically accurate and a good narrative writer. I would just let this one go for now. Let's see if anything develops with UCI, etc. Take my advice if you can.
I agree with you completely.
S-Works Tarmac SL6 (2019) w/Campy SR EPS v4 12-speed hydro;
S-Works Tarmac SL3 (2010) w/Campy SR 12-speed mechanical rim

johnpuga1982
Posts: 134
Joined: Mon Aug 14, 2023 10:49 pm
Location: New York City

by johnpuga1982

In the post race interview Pogačar states he wanted to stop prior to the right turn. However, his sporting director told him to wait until after the right turn. Pogačar then crashes as he makes the right turn. He also looks at the car and says something to it.

If Pogačar stopped and did a bike change when he wanted to there would be no crash. He's also crashed a few times not due to hookless tires.

LedZeppelin007
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Joined: Tue Dec 08, 2020 3:46 pm

by LedZeppelin007

I think I may have even chimed in about how I didn’t think the hookless design of the 4.5s was the cause of Pogi’s crash. On a descent today, had a catastrophic blowout on my 353s with Pirelli P-Zero Race Speedcores (30c) running 60mL of sealant and 62psi.

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mikehhhhhhh
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by mikehhhhhhh

LedZeppelin007 wrote:
Tue May 21, 2024 6:30 pm
I think I may have even chimed in about how I didn’t think the hookless design of the 4.5s was the cause of Pogi’s crash. On a descent today, had a catastrophic blowout on my 353s with Pirelli P-Zero Race Speedcores (30c) running 60mL of sealant and 62psi.

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Sent from my iPhone using Tapatalk Pro
Sounds like you came out the other side unscathed and I'm glad to hear it. Sounds like a scary experience!

Was there any catalyst for the blow out like a pot hole? Any damage to the tyre?

LedZeppelin007
Posts: 709
Joined: Tue Dec 08, 2020 3:46 pm

by LedZeppelin007

mikehhhhhhh wrote:
LedZeppelin007 wrote:
Tue May 21, 2024 6:30 pm
I think I may have even chimed in about how I didn’t think the hookless design of the 4.5s was the cause of Pogi’s crash. On a descent today, had a catastrophic blowout on my 353s with Pirelli P-Zero Race Speedcores (30c) running 60mL of sealant and 62psi.

Image
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Sent from my iPhone using Tapatalk Pro
Sounds like you came out the other side unscathed and I'm glad to hear it. Sounds like a scary experience!

Was there any catalyst for the blow out like a pot hole? Any damage to the tyre?
No damage to the tire. Seems to have simply been the force and heat generated by braking and leaning hard into the corner


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