Note to self: buy hookless rims.

Jeepers this hits home. I have actually worked with Morgan a bit as I had one of their tires do this to me on a ride a few months back. The Challenge tire was VERY VERY tight on my Bontrager rim and I believe it was more of an install issue in my case in that even at 100+psi the bead would never fully climb onto the rim properly....I think....

Either way I've since found a solution running HED rims and Panaracer tires. Not because I'm paid to do it, but because setup, service in the field, and reliability all seem like perfection with that gravel combo. Same with the new HED 29er. Finger tire install / removal on that rim and rock solid reliable.

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24 Hour World TT Champs-American record holder
Fat Bike Worlds - Race Director
Insta: chris.s.apex

To further confuse the situation, going hookless is not a panacea. The Enve SES rims are hookless and have had similar problems of cutting casings - Enve warns against using certain tires with all their rims, hookless or not.

Edit: the above VN article indeed mentions the Enve SES issue as well (or what Enve would call a "tire issue")

Interesting read.

Huh, just when I thought I understood... Why the heck are there tubeless rims without hooks? My understanding was that was a fundamental part of the tubeless wheel/tire combo even working.

Hooks aren't a fundamental part of any clincher system, tubeless or otherwise; they're just a safety feature that makes it harder for a section of the bead to crawl upwards. In theory, with a non-stretchy precisely-sized tire bead sitting snug on the "shoulder" all around a rim, there's no slack in the bead and therefore no risk that it'll crawl upwards anywhere.

Until the late 1970s, it was standard for clincher rims to lack hooks. This sounds kind of crazy when you consider that tire and rim manufacturing tolerances weren't as good as they are today. But the inner tube helps somewhat to hold the tire bead in place, and blowoffs generally didn't happen as long as you were conservative with tire inflation.

Interesting. I knew it wasn't required for tubes. Though I only "knew" that because it just made sense in my head because of the tube.

I (incorrectly) assumed that a tubeless wheel meant, among other things, that it had the hook there as a safety measure.

Learn something new everyday!

car and motorcycle tubeless rims don't have hooks either. They aren't necessary with proper tolerance

I wouldn't be surprised if the stiffness of car tires helps too. Relative to their casing tension, car tires are insanely beefy and rigid compared to bicycle tires.

This would seem to be supported by things like how Gravelkings have less of a blowoff-prone reputation than Rene Herse tires, even though both are made by Panaracer and should theoretically use the same beads. Rene Herse tire casing is thinner, and it's quite stretchy in the non-radial direction.

Both the stiffness of the tire and the rim manufacturing precision help this. The tolerances of cast and machined wheels far exceeds that of bikes. Source: me knowing the tolerances, machines, robots and tolerances of of my businesses clients car/airplane wheels.

That is true too, if you've ever seen a tire installed, it takes a lot of muscle(hydraulic in most cases) to get the bead over the rim lip and also to seat the tire. I personally only trust tubeless setups that fit tightly when installing, and usually require a beadjack to install. If its loose I generally run an extra wrap of stans. Haven't experience an issues with my RH/Compass tires but they are the newer tubeless ready types with the coating on the sidewalls and I believe a stiffer bead like the panaracers

As far as the Enve wheels, iirc, the AR rims are hookless, the other road rims have bead hooks.

' tubeless is a red herring here'

Didn't see any mention of one common cause of this: Poorly adjusted brake pads that touch the tire sidewall, eventually cutting through.

ENVE take on hookless and hooked https://www.enve.com/...-and-who-theyre-for/

We've written on the hooked vs hookless issue here as well: https://www.slowtwitch.com/...s_Rim_Tech_7386.html

Hookless beads and high road pressures bring on another potential problem - tire blowoffs in the case of a tire that's too large (which isn't an issue with MTB tires and low pressure). ENVE has a specific list of approved and unapproved road tires that may be used on their hookless rims. They've told us that the unapproved tires either have beads that are too flexible, or they've measured too large of a variation in bead diameter.

But yes, hookless beads to remove the potential issue of a too-sharp carbon clincher bead hook.

I think it’s a entirely different issue that’s just applicable to tuned or tubeless tires. Most of use cases here are also tubeless tires on disc brakes rims.

there's a lot of backstory here. i believe that the common thread between lennard and morgan was steve hed. there was kind of a hed posse back in the day, and they were both in it, morgan as the longtime right hand man for wen hsieh at KHS, then ritchey's head in europe for many years. then he formed his own brand, OVAL, sold it to advanced (owner of fuji america and kestrel) and he got out while the gettin' was good and joined the family business (thru marriage), which is challenge tire. very strong industry guy. and lennard was dead right, morgan is the ringleader not specifically of anything specific to ETRTO, but to the efforts to forge a common standard between ETRTO and ISO.

since then the ETRTO has come out with a standard for tubeless and lennard and morgan point out (i think) that there is no standard for tires, only for wheels. the duty of the tire maker is to make tires that conform to the wheel standards. my sense (my guess) is that the hope for a common standard is moot. the standard will be, and probably already is, whatever the ETRTO says it is, because most of the big bike tire companies are just big tire companies and they follow the ETRTO on everything (bike tires, car tires, tractor tires, airliner tires). the bike-only tire makers like schwalbe also simply build tires to ETRTO's wheel standard.

today, if you buy road tubeless tires from schwalbe, conti, hutchinson, you're buying tires that conform to ETRTO standards, and if you buy wheels from HED, Zipp, DT Swiss/SwissSide, etc., you're fine. you will have no problem. the tires are also easier to get on than they used to be.

i've ridden quite a bit on challenge gravel tires. wonderful tires. but you're right. a biatch to mount. morgan gave me a mounting tool. in my opinion, they need to remake the molds so that their tires are slightly bigger and don't need a mounting tool.

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Dan Empfield
aka Slowman