Rider sues Rene Herse Cycles over alleged tubeless tire ‘blowoff’

Bottom line:

• before 2022 (and the new ETRTO standard), mounting tires on rims was hit or miss - unless someone (like ENVE or Zipp) actually tested a tire and rim combo to verify it was compatible.
• now in 2022, you can buy a tire and rim that conform to a useful ETRO standard, but to you know if your tire or wheel meet the standard?   Does any consumer know?  nope.   Legally you can't even disclose what is in the standard.
• The bike industry has made great progress here, but its still lacking
• The lack of any decent margin of safety should concern all of us.  If a tubeless hookless tire/rim is certified to 5 bar (72psi), but blows off at 80psi - that type of precision should be reserved for rocket engineers.  Literally.  

As a tire geek (and engineer), I've been following this for years.  I've spent 2 years saying "there is no standard, but a standard is coming soon".  Well the new ETRTO standard is here.  Its top secret, costs like 500€ to purchase a copy, and you can't tell anyone what is in it.  

Obviously the bike industry has a serious problem and still has a way to go.

Before 2022, it was hit or miss.   Tubeless has to be very precise, unlike tubed.   With tubed tires we safely went well outside the ETRTO guidelines, because like with most engineering ventures, there was a significant "margin of error" (safety factor).  For ETRTO, it used to be 1.5.  Now that safety factor can be an insane 1.1.   That should give us all a little pause.  No way I'm putting 72PSI in my front tire (unless it was specifically tested and validated to have much higher blow off pressure)

Before 2022, some tubeless tires were tight, some were loose.  Some wheels were slightly oversized, some were not.   It was hit or miss as to if a tire would work.   Some were so tight as to be impossible to mount, while others were way too loose to be safe.  For instance, the Conti 5000 was next to impossible to mount on my hookless rims because they went a bit too far in the safe direction (well, beats going to the hospital).  They are labeled "for hooked rims only" even though a conti engineer will tell ya they are fine on hookless as long as you stay below 5 bar (I did).  The new generation of the 5000 is both easier to mount, and more precise on what type of rim you can use it with.

mosinglespeeder wrote:would using a latex or standard tube make it less likely to blow?  Interested, I just bought a set but were going to run tubes but like my teeth and don't pleasure eating pave'

yes, it distributes the pressure differently and pushes the tire against the sidewall (& it can't burp).

Angstrom wrote:As far as I know, as of 2019 there was not a uniform industry standard for road tubeless rims and tires.  Anyone running road tubeless was on their own unless their rim and tire combination had been specifically approved by one or both of the manufacturers.
Road hookless in 2019 was even more of an unknown.
The OP states that Mr. Little saw nothing saying he shouldn’t use that rim & tire combination.  Based on everything I’ve read about road tubeless in the past few years, I’d rather look for evidence that a particular combination has been tested and approved.

thanks Angstrom, you are correct.  You hit the nail on the head.

zen_ wrote:My issue with hookless rims, and please correct me if my logic is wrong, is that it's only approved with tires that are manufactured to strict tolerances (not too loose). That's actually a great thing because it's ridiculous how much tires can vary in that regard, but the bead still stretches on pretty much any tire over time. I don't understand how that works since some tires seem to stretch quite a bit.

Hookless rims are probably the way to go on a bike tire; rim bed holds the tire into place. A hook does give an extra margin of safety, but on the other hand tires have blown off because the rim that comes out of the mold must have additional machining on it to make the lip, and sometimes that process creates edges that will cut a tire.  Carbon fiber doesn't like to be carved out very much.  The more complex you make the wheel, the higher failure rate you are gonna have.

stu wrote:Typical automobile rim (J or JJ) flanges are 17.3 or 17.5 mm high, compared to bicycle rim flanges 5.5 to 6.5 mm high.  Most automobile rims are also smaller in diameter, so an automobile tire would have to stretch (fractionally) maybe 4 times as much to blow off.  Also automobile tires have stiff wire beads and run at lower pressures than road bike tires.

You are right, the factor of safety there is much larger than bike tires - not really comparable at all.

mtbnut87 wrote:
This is a great point, and very sad, but not why I shared this....    I just remember anecdotally in a few threads on these tires that people had mentioned that they had had them come off the rim when installing them.   This was the first time I had heard of one coming off when riding...

A year ago I read something in Lennard Zinn's column about a guy who was riding "road tubeless" on his bike and casually mentioned that the next thing he knew he was in the ICU.  He had crashed and was airlifted to the hospital as his "road tubeless" tire had let go at speed (a decent I think).   High pressure, low tire volume, and speed are a frightening mix when you think about the consequences (or hear about them).   Personally I don't go above 60psi or below 32mm tubeless or hookless.

ljsmith wrote:
...My point was simply that there is nothing inherently unsafe with hookless rims.  Hookless rims for bicycles are designed to deal with the couple of hundred pounds they must deal with.  The fact that RH tires are poorly designed has nothing to do with whether hookless rims are a good design or not.

Yeah, uh, no - its not that simple.  
look at the tolerances that must be maintained, how easy it is to meet those tolerances, and what the factor of safety is to prevent blow-off.    I have gone well beyond the PSI limit with car tires, and with old school bike tires (aluminum hooked tubed).    They have a significant factor of safety designed into them (~1.5).  Today's bike tires do not.    Sure, if we wanted to go to "discount tire" and have a professional mount our bike tires on our heavier and more overbuilt rims for our bikes, we could have the same factor of safety built into our bike wheels/tires.   Yes, you would get a flat on a gravel ride, and you get your bike "towed" to the tire store to get your tire changed.  Or we could just go back to extruded aluminum hooked rims with tubes.