The ongoing hookless rims saga

[benb]

Originally Posted by Mark McM

Well, a number of frame/bike makers have gone back to threaded BBs after a few years using pressed in BBs, so anything is possible.

Bicycle product technology has moved in oscillating cycles for decades. First it was short cranks, then it was long cranks, now its short cranks again. First it was round chainrings, then it was eccentric chainrings, then it was round chainrings again, then it was eccentric chainrings again, then it was round chainrings ... And for clincher rims, first it was hookless, then it was hooked, then it was hookless again, and for all we know it may go back to hooked.

To a certain extent when they reverse themselves I think it shows they're not doing enough testing and/or are using consumers as their testers.

They are most certainly trying to use Pro riders as testers from some of the Pro accounts.

Which is all disgusting considering the cost increases.

[benb]

Originally Posted by RoosterCogset

I will say, Giant is odd one out on this issue. They sell TCRs with hookless rims matched with their own 25mm tires. While pretty much any other tire maker won't spec their 25mm TL tires for hookless. Mind you, their ID rim widths are less than 20mm (19.4mm).

Giant might have done enough testing to know their combination is safe.

It's really whether or not you have to worry about anything when changing to a different tire, and it's perhaps the case that Giant did something in the design of their rims that is safer than other brands.

It's not like it's impossible for these problems to occur with other types of rim setups.

I had the blowoff problem with Velomax (became Easton IIRC) wheels + Vredstein Fortezza Tricomp tires years ago with tubes. It was very similar to the problems the Youtuber was sharing with hookless/tubeless. The blowoffs occurred when I was not riding the bike. It was marginally OK apparently. But after I'd come back from a ride there was something going on where there was no weight assisiting the bead and the tire and/or rim cooled off at a different rate or something and the front tire would explosively blow off the rim.

I never figured out what it was, I just instantly switched tires and had no more issues. I had multiple instances of the tires do it, I'd bought a bunch of the tires on a sale, IIRC after a PSA here. IIRC those tires must have been slightly large diameter as they were ultra easy to mount with fingers.

[Waldo62]

More fodder
https://www.cyclingnews.com/news/for...gendt-blowout/

[.RJ]

Originally Posted by Waldo62

More fodder
https://www.cyclingnews.com/news/for...gendt-blowout/

If 1mm in tire width is what makes a difference, the safety margins seem awful thin - but - putting this into perspective, how many miles have pro racers put in on a similar (hookless + tubeless) combo just in this spring alone? And we have just 1 incident like this?

But for the rest of us we dont ride for pro teams with pro mechanics preparing our bikes every day...

[Mark McM]

Originally Posted by Waldo62

More fodder
https://www.cyclingnews.com/news/for...gendt-blowout/

From the article, in an interview with a team mechanic:

Firstly, we asked if inserts would still be used:

“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. 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.”

Is the mechanic saying that that tubeless tires on hookless rims are prone to having their tires come off easily unless an insert is used? If so, then why aren't tubeless tire and hookless rim manufacturers mandating that inserts be used? The mechanic also offered no explanation as to why the insert didn't prevent De Gendt's tire from coming off.

[Mark McM]

Originally Posted by .RJ

If 1mm in tire width is what makes a difference, the safety margins seem awful thin - but - putting this into perspective, how many miles have pro racers put in on a similar (hookless + tubeless) combo just in this spring alone? And we have just 1 incident like this?

One instance that has gotten recent news coverage. There have been eyewitness reports of other tires blowing off of hookless rims recently that have not received news coverage (see articles and podcasts linked above).

[benb]

Also why the UCI rules don't agree with the ERTO rules.

[Spdntrxi]

Originally Posted by Mark McM

From the article, in an interview with a team mechanic:



Is the mechanic saying that that tubeless tires on hookless rims are prone to having their tires come off easily unless an insert is used? If so, then why aren't tubeless tire and hookless rim manufacturers mandating that inserts be used? The mechanic also offered no explanation as to why the insert didn't prevent De Gendt's tire from coming off.

I think the mechanic probably is misunderstanding the use case .. I dont know the size of the inserts used, my guess might be medium since this internal width (25 on Zipp353) and possibly 28mm tire. The are not designed to increase the hold of the hookless bead. They actually shrink a little under pressure and expand (a little) when that pressure is lost.

They are alot firmer vertically then they are laterally so with enough pressure they are coming off with the tire.

[MikeD]

Originally Posted by .RJ

If 1mm in tire width is what makes a difference, the safety margins seem awful thin

Before all this tubeless nonsense, Continental said that the Max pressure rating on the tire is 1/2 of the blowoff pressure. That's a safety factor of 2! What is it now with hookless and tubeless?

[bikinchris]

Originally Posted by MikeD

I'm no fan of hookless rims, but there was a statement in that article that was quite odd:

Hansen said that there were even bigger issues in the past when teams used hooked rims with hookless tires, something he described as “an even worse disaster.”

I never heard of a hookless tire?

I think they mean beadless tires an NO ONE with any sense would ever think of using beadless tires with hooked rims.
I said it before, the bike industry abandoned hookless rims before for a good reason.
And yes, the bike industry has traditionally been full of solutions no one EVER asked for.

[Mark McM]

Originally Posted by bikinchris

They mean beadless tires an NO ONE with any sense would ever think of using beadless tires with hooked rims.
And yes, the bike industry has traditionally been full of solutions no one EVER asked for.

????

All bicycle clincher tires have a bead (which are necessary to hold the tire on the rim, even a rim with hooks).

Maybe you mean a tires with tubeless beads? Tubeless tire beads have a more distinct square shape (to seal with the rim sidewalls better), and may be stiffer and made with higher precision than non-tubeless tire beads.

[fa63]

Technically, the safety margin for hookless and tubeless can be as little as 10%. I am sure there are folks who have pumps that have a +-10% gage accuracy. That said, I doubt any major manufacturer is designing to a factor of safety of 1.1 (Giant and Enve are on record saying they design to at least 1.5).

Originally Posted by MikeD

Before all this tubeless nonsense, Continental said that the Max pressure rating on the tire is 1/2 of the blowoff pressure. That's a safety factor of 2! What is it now with hookless and tubeless?

[Mark McM]

Originally Posted by MikeD

Before all this tubeless nonsense, Continental said that the Max pressure rating on the tire is 1/2 of the blowoff pressure. That's a safety factor of 2! What is it now with hookless and tubeless?

Well, ISO specifies that the minimum blow-off pressure for tires on hookless rims is 110% of the rated pressure. Since the maximum rated pressure for hookless rims is 72.5 psi, the minimum allowed blow-off pressure would be 80 psi. That's not much of a margin (and perhaps below the accuracy of gauges on many pumps). I seem to recall that for hooked rims, the minimum blow-off pressure was 150% of rated pressure - obviously a much greater margin.

Which leads to an interesting issue - while most hookless rims are for disc brakes, there are some hookless rim brake rims. On a long steep descent, where braking is required to stay at a safe speed, braking heat can increase pneumatic pressure by more than 10%. So are hookless rims a safety issue with rim brakes?

[fourflys]

Originally Posted by RoosterCogset

I will say, Giant is odd one out on this issue. They sell TCRs with hookless rims matched with their own 25mm tires. While pretty much any other tire maker won't spec their 25mm TL tires for hookless. Mind you, their ID rim widths are less than 20mm (19.4mm).

they also seem to have a pretty rigorous testing protocol as well.. and they list other manufacturer's tires they have tested as well as a known good..

https://www.giant-bicycles.com/globa...ess-technology

[Baron Blubba]

Originally Posted by AngryScientist

My guess is that the vast majority of people who go into a bike shop and buy a complete bike dont really know the technology too well.

Baron, do you tell your customers who you sell hookless wheels explicitly that they have hookless wheels and that they need to adhere to a certain pressure band and type of tire? Seems like when buying a complete bike that bit could get lost.

I think you're incorrect about the vast majority. My experience is that the vast majority is over-informed and under-experienced, which equals being A) overwhelmed by information, much of which is conflicting (see this thread, I rest my case), B) unable to prioritize which information is more concretely true or simply more important than another piece of information (weight or aero, tubed or tubeless, electronic or mechanical, function or form, boutique or big name, endurance or race, deep dish or shallow or mid, hookless or hooked, wider or narrower, lower psi or higher, frame or components, D2C or B&M, Orange Seal or Stan's, Gatorskins or GP5000's, integrated or exposed, one piece or two, Dura Ace or Ultegra or 105 --or maybe Sram? Or maybe Campy?, buy nice or buy less nice and upgrade later, etc etc.)
I actually just had an experience with a customer yesterday who is building up a Dogma F12. She ordered Princeton Carbon Peak 4550 for it. She received the brand new ones instead of the 'old' model she thought she was getting. She immediately went online to research the differences (aside from the funky profile). She saw that the new ones were hooked, and was worried that the wheels had regressed back to old technology, because the originals were hookless.

Anyway, yes, we do inform all of our customers about the nature of their hookless wheels, when applicable. Assuming all shops are equally conscientious (I'm being generous here, just roll with it), it's that for you, me, my coworkers, and most everyone on Paceline, the explanation of what hookless is and what care must be taken with a hookless system, is perfectly understandable First Language. For many people, though, it's not. And while they might nod their heads in understanding in the store, they might not entirely comprehend; and if they do, they might forget, because how often does a casual cyclist replace their tires or think about their wheel/tire system? I know every time I need to know anything about anything that's not a bike or a toy, I have to look it up --because I'm like a cow, everything goes in one ear and out the udder. Most people are the same.