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Pro cyclists’ union “not happy” with hookless wheels after “freak” blowout causes Thomas De Gendt crash – but team defends tyre system as “100% within the rules”

“There are a lot of people who want this banned out of the peloton… One day there will be a mass crash as a result,” CPA president Adam Hansen said

The professional cyclists’ association is “not happy” with the increasing use of hookless rims and tyres in the pro peloton, CPA president Adam Hansen has said, after Thomas De Gendt’s recent heavy crash at the UAE Tour was seemingly caused by a freak tyre blowout.

Lotto Dstny veteran De Gendt hit the deck in an apparently out of the blue spill during Friday’s fifth stage of the UAE Tour, with subsequent television images showing the Belgian’s front tyre almost completely detached from the wheel, sealant splattering the frame and wheel, and a broken foam insert tangled in the front fork.

Following the stage, having escaped with only a few cuts and bruises, De Gendt took to Twitter to thank Soudal Quick-Step’s staff for assisting him after the crash – as the Lotto Dstny car was busy helping a teammate in the breakaway at the time – and asked for images in order to ascertain “what I hit with my front wheel”.

But on the pristine, mostly characterless main roads of the UAE, the cause of the 37-year-old’s crash may have had more to do with a mechanical mishap and divisive equipment selection than a stray stone or pothole on a super smooth carriageway.

As former pro Ronan McLaughlin identified for Escape Collective, Lotto Dstny’s use of hookless rims – and a simple mismatch between the 25mm internal width of the team’s Zipp 353s, which are recommended to only be used with tyres of 29mm or wider, and their 28mm Vittoria Corsa Pro tyres – were arguably the primary cause of De Gendt’s sudden spill, rather than a manufacturing error or bump in the road.

Hookless rim Fast FWD - 1

> Tubeless wheel tech: What’s the difference between hooked and hookless and which is better for you?

An increasingly popular presence in the peloton in recent years, hookless rims, as the name suggests, do not feature hooks to hold the tyre onto the rim. The system instead relies on tyre pressure, specially designed tyre beads, and tight tolerances to hold the tyre in place.

While, as we noted back in 2021, hookless rims contain a variety of advantages over their more old-fashioned hooked counterparts, such as a cleaner tyre and rim interface for better aerodynamics, while enabling manufacturers the chance to construct lighter and stronger rims at a lower cost, they also are limited to a maximum pressure of 73psi.

And it’s that maximum pressure, and the ability for tyres to exceed that limit and detach themselves from the rim after hitting a bump, which has prompted CPA president Adam Hansen to speak out against the use of hookless systems in the professional peloton.

“The CPA is not happy with riders racing on hookless system in the peloton. There have been concerns from riders and teams with this new system,” he tweeted this morning.

Thomas De Gendt crash, 2024 UAE Tour (Discovery+)

Speaking to Velo, the Australian, who was teammates with De Gendt at Lotto between 2015 and 2020, said the riders’ union was “100 per cent against hookless rims”, claiming that they could potentially cause a “mass crash” in the bunch.

“When you look at the images of Thomas De Gendt’s bike, his tyre came off, the safety foam inside got caught in the fork, and that locks up the front wheel,” Hansen said.

“Some teams are racing with hookless rims. This crash is why the CPA are 100 per cent against hookless rims.

“Tyres should not come off a rim. The maximum psi these hookless tyres can have put in them is 73, and if you hit something for sure it goes above the maximum 73psi rating on impact. That is why tyres are coming off.”

> Chloe Hosking blames CPA for not standing up for Julian Alaphilippe after Patrick Lefevere comments (and Adam Hansen hits back)

He continued: “We have heard from some teams that they have put tyres on before, they left them out in the sun and their tyres just pop off.

“But the manufacturers really like them because it is much easier to produce the rim, you need less moulds for this. The rims are much lighter, it is easier for production, so they are pushing for this.”

Hansen added that some teams previously combined hooked rims with hookless tyres, a practice he described as “an even worse disaster”. But while that particular non-compliance issue is a thing of the past, the Australian believes the proliferation of hookless systems could have a devastating impact on the bunch’s safety.

“There are a lot of people who want this banned out of the peloton because you can actually take down other riders. One day there will be a mass crash as a result,” he said.

2022 Cadex 50 Ultra hookless rim profile wheels

> Is hookless the future, why are modern bike wheels so wide, and should I buy direct from China? Your wheel tech questions answered

However, despite Hansen’s criticism, Lotto Dstny’s staff have insisted that the tyre and rim combinations they use are perfectly within the UCI’s rules and according to industry standards.

“We use, obliged by the UCI, 28mm tyres on a 23mm or 25mm inner rim. That is according to all prescriptions by the UCI, from Zipp, and from Vittoria, so for sure we are 100 per cent in the rules,” one mechanic told CyclingNews ahead of today’s Kuurne-Brussel-Kuurne.

The Lotto Dstny mechanic also confirmed that the Belgian team would continue to use the inserts that were so dramatically on show in the wake of De Gendt’s crash, which theoretically help keep a tubeless trye attached to a hookless rim in the event of an instant puncture.

“We’ve done it from day one, with a former brand also; we always use inserts. I certainly believe you get a loss of 1.0 or 1.1 watts, but we do it for the security of the riders,” the mechanic said.

“If you have a hookless rim and a tubeless tyre and you get an instant flat it goes off like nothing. Imagine if a rider takes a descent and the tyre goes off… they could be dead.”

Ryan joined in December 2021 and since then has kept the site’s readers and listeners informed and enthralled (well at least occasionally) on news, the live blog, and the Podcast. After boarding a wrong bus at the world championships and ruining a good pair of jeans at the cyclocross, he now serves as’s senior news writer. Before his foray into cycling journalism, he wallowed in the equally pitiless world of academia, where he wrote a book about Victorian politics and droned on about cycling and bikes to classes of bored students (while taking every chance he could get to talk about cycling in print or on the radio). He can be found riding his bike very slowly around the narrow, scenic country lanes of Co. Down.

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hmsgenoa | 1 month ago

Couple of things, Lotto's wheel partner this year is the Orbea Brand and their wheels Oquo talk about having a 'mini-hook'. Are we sure they are Zipps?! I don't think they are according to team sponsors/partners list and also Vittoria tyres say do not mount on a hookless rim even on the Terreno Mix 45mm Gravel tyres so I do not believe the team would make the mistake of mounting them on a hookless rim if that's the case with their road tyres. **Post script** Just seen the video rather than the picture and it is a Roval wheel going in even though their sponsor list says 'Oquo'. Roval road wheels I believe are hooked.


Fluffed replied to hmsgenoa | 1 month ago
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Not sure what video you are watching, but those are (hookless) Zipp 353 NSWs, they are quite distinctive.

james-o | 1 month ago

"The maximum psi these hookless tyres can have put in them is 73, and if you hit something for sure it goes above the maximum 73psi rating on impact. That is why tyres are coming off.”

I doubt it is why they're coming off and you'd expect the tyre and rim manufacturers considered this. If 73PSI is a stated maximum they will have been tested at that pressure plus a generous safety factor. 

MattieKempy | 1 month ago

This is basically just like the disc brake furore of a few years back where discs were apparently the devil's work, randomly slicing riders' limbs open at will throughout the peloton until, all of a sudden, they weren't.

Psi Squared | 1 month ago

Not all pro teams are using hookless rims. Visma/Lease A Bike uses Reserve tubeless rims that have mini-hooks.  Likewise, AG2R is using Swiss Side tubeless rims, and those also have hooks.  There are others.  Teams can refuse to use hookless rims, and if that happens then Zipp, Enve, and others will have to make a change.

Xenophon2 | 1 month ago
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I do wonder what the benefits are of a tubeless tire on hookless rim + sealant + tire insert vs conventional tire on normal rim and latex tube....

...certainly if the bloody thing blows off the rim, with potentially catastrophic consequences.

But them I'm obviously no pro.  Anecdotally, I had a tire from a -very reputable in gravel circles- brand blow off a conventional hooked rim when I hit a rut.  It was inflated to 65% of its max pressure rating.  After that and considering the number of times that sealant didn't quite manage to seal fast enough I reverted to tubes.

OnYerBike | 1 month ago


 Lotto Dstny’s use of hookless rims – and a simple mismatch between the 25mm internal width of the team’s Zipp 353s, which are recommended to only be used with tyres of 29mm or wider, and their 28mm Vittoria Corsa Pro tyres

Point of information. Using 28mm (labelled) tyres on 25mm internal width wheels is contrary to the ISO specifications. 

However, as pointed out in McLaughlin's article linked, Zipp explicitly state that 28mm Vittoria Corsa Pro tyres are approved for use with the 353 NSW wheels. In fact, not only are they approved, Zipp claim "You can ride 28mm tires. That’s what we optimized everything around" (

So I think it's missing a huge part of the picture to simply state that those tyres are not recommended with those wheels - they were recommended by the manufacturer, contrary to the ISO standard. 

wickedstealthy replied to OnYerBike | 1 month ago

That's not correct at all. 28mm was approved for 25mm inners before this hookless shit took off. Also not all 28mm are made equal. Take a 25mm gp5000 that is considerable smaller then a 28mm given their labelled size. A 25mm runs very small and you can hardly get it on a 23mm inner rim for which it is approved. I run 25iw reserve hooked wheels and Pirelli 28mm tires. They come up at 30.5mm and run them on 4.6bar. If they flat the keep on the rim. Hookless is simply easier for them and takes away another safety boundary. 
As mentioned hitting stones raises the point pressure far beyond what normally a hookless/tyre can tolerate and then you get this shit

A friend of mine ran a tubeless tire on a hookless rim 30mm and it just came off after hitting a stone resulting in a severe crash. It gets off far too easy at cost of safety for the rider 

OnYerBike replied to wickedstealthy | 1 month ago

I have no idea why you think that is relevant to what I have said, let alone demonstrates anything I have said is "not correct at all". 

Psi Squared replied to wickedstealthy | 1 month ago
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It doesn't matter at all what 28mm was approved for in the past.   The ISO spec now is that the smallest tire you can run with a 25 mm internal width rim is a 29mm tire. That Zipp and Vittoria say 28mm is fine demonstrates a big issue: manufacturers not abiding by standards.

In terms of the UCI approving 28mm tires for 25 mm internal width rims, that just reinforces what's already known about the UCI: they have little concern for rider safety.  I'm willing to bet that ISO has done far more testing and understands tire size and rim size compatibility far more than the UCI.

Glov Zaroff | 1 month ago
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fwhite181 | 1 month ago
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I just hope this begins to kill off hookless rims on road bikes (again). 'Hookless' was pretty much the standard until the 70s when we invented this incredible new idea called 'hooked rims'...which were apparently faster and better because they held the tyre more firmly on the wheel, allowing the use of more-supple sidewalls and higher pressures).

The only real benefit of a return to hookless rims is to the manufacturers who get to make a cheaper rim and then charge us chumps more for it because it's 'new' and 'faster'.

The Maso | 1 month ago

I could be wrong on this but I think the 73/72.5 max. psi rule is much misunderstood and /or miscommunicated (which is why I could be wrong). My interpretation (of  Giant's own testing procedures) leads me to believe that the 73 psi limit is for those tyres that have not been tested - where the testing goes well beyond that pressure level.

The issue even on their own website is the wording - they talk about indicated sidewall maximum pressure and not ACTUAL inflated pressure; 

"Please be aware that if you choose to use a tyre with an indicated maximum pressure above 72.5psi (5 bar) that is not on the list of tyres that have passed the Giant test protocol, YOU DO SO AT YOUR OWN RISK, as the tyre may not function properly with the Giant hookless WheelSystem.

Please note that if the maximum pressure indicated on the sidewall of a tyre is below 72.5psi (5 bar), the tyre is tubeless compatible, and is not indicated as being incompatible with hookless rims, it can be used with Giant hookless WheelSystems and does not have to appear on the "What Tyres Can I Use" chart."

But the testing procedure takes their tested tyres to 1.5 times their recomended maximum, which could be over 160psi;

"HIGH PRESSURE TOLERANCE TEST: First, the tyre is inflated to 72.5 psi (5 bar), an average minimum pressure for most riders on 25c tyres, and must withstand this pressure for 24 hours without blowing off. Next, the tyre is inflated to its recommended maximum pressure and must withstand this pressure for 24 hours without blowing off. After that, the tyre is inflated to 1.2 times the recommended maximum pressure and must withstand this pressure for 24 hours without blowing off. Finally, the tyre is inflated to 1.5 times the recommended maximum pressure and must withstand this pressure for 24 hours without blowing off. The final number of 1.5 times the recommended maximum pressure is intended to simulate such extreme conditions as hitting a square edge or a pothole at high speed causing the tyre pressure to increase suddenly. If the tyre has been able to withstand the four pressures for 24 hours respectively without blowing off, it passes the Giant high pressure tolerance test. For your own safety, please do not inflate the tyre over the recommended maximum pressure or attempt to replicate this test."

So, I don't believe that there's a hard limit of 73psi unless the wheel manufacturer explicityl says so - Giant certainly doesn't seem to (though I could be wrong).

When I picked up my TCR with SLR-1 rims and Cadex 25mm Race tyres, the shop had them inflated to <>85psi - and I queried the pressure; they said it was fine.

PJSA replied to The Maso | 1 month ago

I was also confused by this and reached the same conclusion as you have. Giant's hookless wheels and tyres are designed to be used together and tested way above the 73 psi limit, which applies to combinations that they haven't tested. If I enter my weight, tyre width and rim width into their tubeless pressure calculator it recommends a pressure of 82 psi. For the rim and tyre width combination supplied on TCRs at the moment you only get down to a recommended pressure of 73 psi at a rider weight of 60kg.

OnYerBike replied to The Maso | 1 month ago
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As far as I can tell, this is another example of manufacturer's advice differing from ISO standards. I.e. you are correct that Giant say you can inflate certain tyres above 73 psi, but doing so is nonetheless contrary to the ISO standards.

ROOTminus1 | 1 month ago

The wheel specifies use with a minimum tyre width of 29mm, the mechanics put on 28mm tyres and hoped it'd be fine? That's not a tech issue, that's an RTFM issue.

What Adam Hansen should be kicking a fuss about is the absolutely diabolical lack of concussion and head injury protocols in the peloton that allowed Adam Yates to get back on his bike and continue the stage after his crash, when he should have been straight off to A&E for an MRI.
Rugby players have accelerometers in their gum shields which if a threshold force is measured, they are immediately subbed off for an independent concussion check. Pro cycling needs something similar where if there's a head impact in a crash, they need independent assessment. If they pass, they can get a sticky bottle back to the pack, fail and they're off to hospital

levestane replied to ROOTminus1 | 1 month ago

ROOTminus1 wrote:

The wheel specifies use with a minimum tyre width of 29mm, the mechanics put on 28mm tyres and hoped it'd be fine?

I've yet to measure a tyre when installed that is actually what is says on the sidewall. Are the mechanics measuring?

ROOTminus1 replied to levestane | 1 month ago
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I'm not defending hookless rims, the only benefits are for manufacturer's profit margins.
Matching rim to tyre widths is a very real problem for every day riders, but it is literally the job of a pro tour mechanic to obsess over details like that.

Sriracha | 1 month ago

for sure we are 100 per cent in the rules,” one mechanic told CyclingNews

sounds like they're trying to get off the hook

rookybiker | 1 month ago

"hookless rims contain a variety of advantages ... such as a cleaner tyre and rim interface for better aerodynamics"

This one always cracks me up. Remember the 105% rule-of-thumb first proposed by HED? The mounted tyre needs to be a bit narrower than the rim in order to keep airflow attached. Hookless rims make this harder (impossible within specs) to achieve, because the hooks actually helped to tuck the tyre in.

The one true advantage of hookless is that they are cheaper to manufacture.

fwhite181 replied to rookybiker | 1 month ago
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Hookless also isn't a new idea - hooked rims weren't standardised until the 70s!

Miller | 1 month ago
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I don't think there is such a thing as a hookless tyre .. there are tyres approved for hookless rims but that doesn't stop them being used on a hooked rim. Non-approved tyres being used on a hookless rim, that could conceivably lead to problems.

KDee replied to Miller | 1 month ago

I was going to say the same thing. No such thing as a hookless only tyre, which I think shows how much BS is being spouted or how confused some of these "experts" are.

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