Continental GP 5000 S TR popped off (Cadex AR 35 wheels)

Wheels, Tires, Tubes, Tubeless, Tubs, Spokes, Hookless, Hubs, and more!

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pushpush
Posts: 280
Joined: Wed Feb 01, 2023 5:10 am

by pushpush

These events are always alarming. I have to wonder about sealant however. How does a tire just fall off the shelf? That seems like a really poor fitting tire/wheel combo. I find that after the first day it is practically impossible to get a tire to unseat/move without using tools because the sealant will have powerfully glued it in place. Even the "easy to mount" tubeless tires I've used wind up cemented to the wheel after a day or two.

How does another brand tire fit on the same wheel? How does the same tire fit on a different wheel? Any notable difference?

kervelo
Posts: 862
Joined: Wed Jan 21, 2009 6:58 am
Location: Finland

by kervelo

Mr.Gib wrote:
Thu Feb 23, 2023 10:06 pm
stjepan wrote:
Wed Feb 22, 2023 8:03 pm
73 psi is max pressure for hookless. It could be that the tire gauge isn't accurate, there's always that. I have a separate digital tire pressure checker, should employ it more often in the future.
Even if a pump is off by a few psi, or a gauge is inaccurate, surely there is adequate overhead beyond the max 73 psi as a safety margin for just this type of error? The tubeless and/or hookless tire/rim system is this idustry is still a bit of a mess. I don't know if it's bad design or bad manufacturing or a combination of both, but these blow-off events should not be happening.
The safety margin is much bigger, at least with Zipp rims:
https://bikerumor.com/insider-interview ... oad-bikes/

The blow-off events do not happen in a larger scale. The hookless tubeless rims have been widely used for years and there has not been any big issues with them. These accidents are similar to rolling a tube from the rim: not very common, but still happens.

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TobinHatesYou
Posts: 12444
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

kervelo wrote:
Fri Feb 24, 2023 7:54 am

The safety margin is much bigger, at least with Zipp rims:
https://bikerumor.com/insider-interview ... oad-bikes/

The blow-off events do not happen in a larger scale. The hookless tubeless rims have been widely used for years and there has not been any big issues with them. These accidents are similar to rolling a tube from the rim: not very common, but still happens.

It's happening too frequently and without much explanation for my liking.
It's not an issue with hooked rims.
Hookless rims have no major advantages over hooked rims besides some weight savings and potential, but not often actualized consumer cost savings.
Hookless does not create a noticeably more aero tire shape according to independent tunnel testing.

I just don't see the point.

warthog101
Posts: 846
Joined: Wed Sep 25, 2013 10:05 am

by warthog101

kervelo wrote:
Fri Feb 24, 2023 7:54 am


The safety margin is much bigger, at least with Zipp rims:
https://bikerumor.com/insider-interview ... oad-bikes/

The blow-off events do not happen in a larger scale. The hookless tubeless rims have been widely used for years and there has not been any big issues with them. These accidents are similar to rolling a tube from the rim: not very common, but still happens.
I have hookless WR50 wheels that are nice and wide.
25mm int, 32mm ext
28mm tyre on the front and 32 on the rear.
The wide rim bed makes a voluminous tyre.
55-60psi is heaps at my weight ~77kg
Not an issue I am concerned about with wider rims and tyres.
Yes I'd be less happy with narrower rims and tyres that need higher pressure approaching the 72.5psi max.

kervelo
Posts: 862
Joined: Wed Jan 21, 2009 6:58 am
Location: Finland

by kervelo

TobinHatesYou wrote:
Fri Feb 24, 2023 8:37 am
It's happening too frequently and without much explanation for my liking.
I think we all agree that even random cases of blow-off is too much.
TobinHatesYou wrote:
Fri Feb 24, 2023 8:37 am
Hookless rims have no major advantages over hooked rims besides some weight savings and potential, but not often actualized consumer cost savings.
According to most manufacturers and reviewers the hookless rims are also more durable, which is nice especially when used off road with lower pressures.

stjepan
Posts: 76
Joined: Sat Dec 05, 2020 10:04 am

by stjepan

pushpush wrote:
Fri Feb 24, 2023 7:24 am
These events are always alarming. I have to wonder about sealant however. How does a tire just fall off the shelf? That seems like a really poor fitting tire/wheel combo. I find that after the first day it is practically impossible to get a tire to unseat/move without using tools because the sealant will have powerfully glued it in place. Even the "easy to mount" tubeless tires I've used wind up cemented to the wheel after a day or two.

How does another brand tire fit on the same wheel? How does the same tire fit on a different wheel? Any notable difference?
Only other thing, apart from a malfunctioning tire, could be that I didn't seat the tire properly around the valve (as others pointed out). Actually hoping it was so, as this would be the easiest solution. Won't know till I ride them again I guess.
Cadex AR 35 are marketed as gravel wheels so I did use them with Cadex AR 40 tires first for a couple of rides on my gravel bike (class 1 gravel, nothing gnarly). No problems. The fact that the wheels rolled so nicely and were lightning fast to engage prompted me to try them on my road bike (with GP 5000 STR). Enter problem. But not immediately, it took 5 or so rides for this to happen. Go figure.

yinzerniner
Posts: 204
Joined: Tue Jun 13, 2017 8:54 pm

by yinzerniner

Mr.Gib wrote:
Fri Feb 24, 2023 7:06 am
That's a joke. Inflate in a cool room, ride in the hot sun - 10% is nothing. I have trouble imagining a group of ISO officials sitting around and deciding in good faith that 10% overhead should be fine for a product on which the users life depends. This just doesn't smell right. I wonder if there was some industry input on this.
Exactly, 10% is a joke since you can easily reach and exceed that safety margin through temperature change and/or a faulty pump pressure gauge.
kervelo wrote:
Fri Feb 24, 2023 7:54 am
The safety margin is much bigger, at least with Zipp rims:
https://bikerumor.com/insider-interview ... oad-bikes/
That's not exactly what the article states. Basically it says
This chart shows their “Burst Pressure” tests, illustrating how high the pressure has to be to blow a tire off of a hookless rim. Tire and rim measurements shown at top, and each point on the black line is a different tire.
But nowhere does it state what the "burst pressure" test is. Is it similar to the ISO/ETRTO tests? Do they just inflate to a certain psi and see if the tire blows off? How long is the tire inflated? What is the age of the tires? Do they account for any type of bead stretch, or tire age? etc etc.

There are very real advantages to manufacturers and consumers for hookless carbon tubeless, however the testing agencies and tire/rim manufacturers need to do a better job of builidng in more redundancy than just 10%. Since the actual max pressure is closer to ~80psi when the redundancy is accoutned for, if we as the consumer are being practical we'd use a similar redundancy rate to clinchers which is ~40-50%, so we as consumers shouldnt' choose hookless unless we're running tires at less than ~55psi. Just my opinion, of course

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Mr.Gib
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by Mr.Gib

kervelo wrote:
Fri Feb 24, 2023 11:41 am
TobinHatesYou wrote:
Fri Feb 24, 2023 8:37 am
Hookless rims have no major advantages over hooked rims besides some weight savings and potential, but not often actualized consumer cost savings.
According to most manufacturers and reviewers the hookless rims are also more durable, which is nice especially when used off road with lower pressures.
I assume that chunky hookless sidewall is much more impact resistant than the skinnier hooked variant. And I also assume it is easier to manufacture a perfect tire bed in the absence of hooks. Not to mention that on carbon rims, the hooks themselves if not perfectly formed, can cause problems. My hooked WR50 cut through the sidewall of two Vittoria Corsas. Others have stated that this is a known problem with Corsas, but I no longer trust any cloth tires on these wheels. Hookless could be great if it never failed.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

Nickldn
Posts: 1863
Joined: Mon Mar 25, 2019 12:35 am

by Nickldn

Mr.Gib wrote:
Sat Feb 25, 2023 2:48 am
kervelo wrote:
Fri Feb 24, 2023 11:41 am
TobinHatesYou wrote:
Fri Feb 24, 2023 8:37 am
Hookless rims have no major advantages over hooked rims besides some weight savings and potential, but not often actualized consumer cost savings.
According to most manufacturers and reviewers the hookless rims are also more durable, which is nice especially when used off road with lower pressures.
I assume that chunky hookless sidewall is much more impact resistant than the skinnier hooked variant. And I also assume it is easier to manufacture a perfect tire bed in the absence of hooks. Not to mention that on carbon rims, the hooks themselves if not perfectly formed, can cause problems. My hooked WR50 cut through the sidewall of two Vittoria Corsas. Others have stated that this is a known problem with Corsas, but I no longer trust any cloth tires on these wheels. Hookless could be great if it never failed.
Hookless has many advantages, including weight and simplicity. BUT it doesn't work reliably at road bike pressures.

Perfect solution for cars/motorcycles/MBT, but not road bikes yet. The industry has tried to lower recommended tyre pressures from about 90-100psi to 65-70psi by increasing rim bed width. But it's not enough.

Can hookless ever work for road? If tolerances for a successful wheel/tyre need to be very high then it's not going to be a realistic option.

I thought Giant was close with their Cadex wheels, but maybe not yet.
Giant Propel Advanced SL Red Etap 11s Easton EC90 wheels CeramicSpeed BB Zipp SL70 bars 6.5kg

Vitus ZX1 CRS Campy Chorus 12s Bora WTO 45 disk brake wheels Zipp SL70 bars 7.5kg

SL8 build with Craft CS5060 Wheels in progress

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