Originally Posted by
elcruxio
I get your point. However that video showed us a small tire on a small rim and it still took the full weight of a grown man hopping on the tire to mount it. Hydraulic tire changer makes the job a lot easier, faster and safer for the tire and rim.
The point in the first video was, that if a hookless tire can be mounted tool free, ie. just by pushing with your fingers, it is not tight enough for it to really be safe.
Mounting tires is and should be much easier than taking them off. That is sorta the point why car rims are made the way they are, so that both beads cannot sit in the bead well at the same time. It is possible to take a car tire off a rim without power tools but you just need really long steel levers to do it.
There's one further major difference in car rims I failed to point out in my last reply on the subject. Car rims have a bead shelf (as tubeless has) that isn't level but is in fact an upwards slope (when looking at the cross section of the rim). When the tire is pressurized, the bead will move up that slope stretching itself tighter and tighter against the increasing circumference of the rim until it can't move up anymore. You'll end up with a really tight stretched seal against the rim. That slope is really useful, because it equates out manufacturing tolerances of tires. Some beads might rest a few mm. closer to the outside of the rim and some might rest bit closer to the inside, but they're all stretched against the rim with enough force to keep them in place.
The end result is that the tire should not come off unless the bead snaps (given how beefy the beads are, unlikely) or there's a rapid deflation and high enough sideways force to the tire (eg. cornering with too little pressure). Technically, you shouldn't need the flange on a tubeless car rim. However it's there and it is quite tall because it's a vital safety feature. If a tire does move, the flange stops it from moving too much or jumping off the rim.
Bicycle hookless rims have a bead shelf that's level. Granted, hooked TLR rims also have a bead shelf that's level but they also have a hook. Without a sloped bead shelf the tolerances need to be exact. If the bead circumference is too large and it doesn't seal against the bead shelf it'll have no choice but to seal against the flange, which is not what you want happening. You want that bead stretched tightly against the bead shelf. One problem that comes from the dimensions of bicycle rims is that they're so narrow that you don't really have enough space to create a slope that's gradual enough so that the tire won't just flop off as soon as pressure is released. Or rather road rims have this problem. With wide MTB rims or even fatbike rims you could achieve a proper slope easily.
I have come across one tire rim combo where I am absolutely positive it would have worked totally fine hookless with no safety issues whatsoever. The rim diameter was oversize and the tire undersize. In the end I needed a bench vise to pry the beads off the rim.
I realize that what I wrote above isn't exactly an endorsement for hooked TLR either. However hooked TLR has proven itself to be reliable and safe. The hook does a lot heavy lifting should the tire burp or move for some reason and it'll work as an additional sealing surface if it has to.
The point of the first video was that even using plastic tools to install bike tires means that the tires don't fit tight enough. That engineer has apparently never used a bead jack. He also overlooks tires from Giant that have beads that aren't steel, but pass pressure tests up to 150% of the maximum recommended value.
For those who haven't got an engineering degree, you need to know that most of what you learn is mathematics, most of which you'll never use, along with some useful formulas like the ones that Hambini presented. New developments may make use of these formulas, but it doesn't eliminate their misuse, or the need to test the products made from their application. The engineer in the video is too young to have much real world experience and has probably never tested a new product design in his life. If steel bead reinforcement is the answer, I'd think that it would already have been tried and tested, but who knows? Maybe some accountant decided that a safe but slightly heavier tire would never sell, so testing was never done.
Not all engineers are professional engineers who have passed a series of exams that prove to someone that they understand theory. It doesn't mean you have any experience. I worked on the development of critical nuclear weapons products, but having a PE wasn't a requirement. Experience and ingenuity were the keys.
I've logged over 15,000 miles on hookless rims and tires with zero problems. I've tested my tire and wheel setups to 85 psi, compared to my normal 55 psi needs. I've used early model Michelin tubeless tires that were not approved for hookless. My last one had so much bead stretch after 9 months that the beads would come off the ledge as soon as the air was let out and I couldn't get air back in fast enough with the valve core in place. I took that tire out of service.