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”

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.

"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. 
 

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.

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.

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.

Quote:

 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" (https://www.sram.com/en/life/stories/five-things-to-know-about-the-353-nsw)

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. 

"DEATH BY HOOKLESS!" is the new "DISC ROTOR MEAT SLICER!". 

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'.

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.

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

Quote:

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

sounds like they're trying to get off the hook

"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.

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.