eduskator

There is absolutely no debate here - like there is no debate on the flat vs round Earth. Disc brakes are better for superior braking needs, just like Earth is round.

I still love rim brakes though (but I don't like flat-Earthers).

georges1

which is false ,in this article you have a nice comparison disc brakes versus rim brakes and another good article debunking the myth heat from rim brakes incrases tire pressure and causes blow out. Each type of brakes has its pros and its cons

Lombard

Would you rather be trampled to death by a hippo or eaten by a lion?

Bah Humbug

Can I pet the lion as he eats me? Because I'd like to pet a lion before I die.

terrymorse 

Blow offs from heavy braking is not false.

Carbonfiberboy 

A little late to the party, but . . .

Firstly, I know nothing about heat-related issues and carbon rims. I've been riding a tandem with 285 lb. team weight and rim brakes in hilly terrain for a long time. I don't think I'd choose carbon rims.

The issue with heat is that at the top of a hill, the descending vehicle has a certain amount of potential energy. By the bottom of the hill, all that potential energy will have been converted into heat energy by two mechanisms: atmospheric resistance and braking resistance. There's no way around that, therefore the problem resolves into two problems: how to maximize the energy lost to the atmosphere and how to dissipate the heat from braking.

Thus one lets the bike run between corners while sitting upright (if not racing) and brakes hard for the corners. What matters here is not so much the intermittent nature of the braking, bur rather that one is dissipating heat into the atmosphere between corners rather than one's rims. Alternating front and rear braking, either rim or disc, will make that rim or disc temporarily hotter than it would have been if both brakes had been used at once. The hotter surface will dissipate heat more quickly than a cooler one, so alternating them makes sense.

I've blown tires off our tandem rims several times while running box section alu rims. I'm friends with a tandem captain who went off into the blackberries after his front rim brake cable failed and his rear disk got red hot and melted whatever it melts and stopped working.

There was a famous tandem group descent of Ventoux many years ago, some bikes with discs, some with rim brakes, and a few with a rim/rear drum combo. The result was that every disc braked bike melted their plastic parts though the brakes still worked. The rim/drum combo did fine, and none of the rim braked bikes had a problem. The fun part about the rim brake result is that all the riders knew to stop and let their brakes cool from time to time. The disc brakers thought theirs were bomb-proof, with an expensive but not dangerous result. Tech is different today, but I think the lesson is a good one.

Tires blow off rims because the internal pressure becomes too great AND the tire material softens at the bead. The solution for alu rims is simply to run a deep rim. A deep alu rim has much more surface area and thus dissipates heat much more rapidly than does a box section rim. I've never blown a tire off a deep alu rum. And it's definitely not the case that the tube overheats. The failure is at the rim/tire joint. A section of tire bead comes off the rim, maybe 6"-8" long, and the tube has a rent in it, about that long and at the same location. Tube failure would not have that result. The tire would simply deflate and not blow off the rim. Tubeless tires do exist.

I don't know that it matters whether the tire is tubeless or not, but it certainly does matter if the rim is hooked. Hookless rims have a pressure limitation. I have thought however that a tube does press against the tire at the bead, which would seem to add strength to that bead/rim joint.

Racing Dan

Can imagine anyone would dare building a hookless rim brake wheel. It'd be a death trap, even more so than it already is.

eduskator

Been using a set of hookless rims for the last 3 seasons and I do not have any complaint whatsoever aside from being limited to certain tires. They've been nothing but great.

Lombard

What is the advantage of hookless rims? To me, that always looked like a catastrophe waiting to happen.

eduskator

Weight, more inner width, lower pressure needed in tires, (claimed) better grip and handling due to the tire not deforming as much as it would with a hooked type rim.

Some will also argue that it's just a way for manufacturers to save money since they're cheaper to produce.

Lombard

Hmmm. Sounds like a solution to non-existant problems.

Maelochs

Lower weight for wider internal width able to run safely at lower pressures? Not saying these claims are true, but if those are true, then hookless is not a solution to non-existent problems, but an clear improvement.

Unless some folks like narrow, heavy wheels at high pressure .... to each his own .....

" "We are all in the grip of Big Hookless' he whispered with his last breath, and a chill ran down my spine. I knew he was right."

SoSmellyAir

I am new to tubeless, but from reading here and elsewhere online (including Roval), lower pressure (compared to tubes) is an advantage of going tubeless. Conversely, going hookless requires lower maximum pressure, and is thus a disadvantage.

eduskator

Hookless rims don't ''require'' a tire that has a low maximum pressure; they require to be compatible with the tire.

These tires often have a maximum tire pressure of 5 bar indicated on them, but you can still use tires that have a higher maximum pressure as long as they've been tested by the wheel manufacturer.

SoSmellyAir

I did not say that a hookless rim requires a tire with a lower maximum pressure. I said that a hookless rim itself is rated at a lower maximum pressure.

For example,
Zipp 303: 73 psi. 303 S Tubeless Disc-brake | WH-303-STLD-A1 | Zipp (sram.com)
FFWD Drift: 72 psi. FFWD Wheels DRIFT 36mm Gravel Disc Brake Carbon Clincher Wheel Set (ffwdusa.com)

Thus, even if a compatible tire itself is rated at a higher maximum pressure, ETRTO says not to inflate it above 73 psi when mounted on a hookless rim.

seypat

Do you know someone named the Tooth Fairy? Oops, that was a tiger. I've heard of men that spanked their monkeys, but none that petted lions except for those two guys in Vegas.

phrantic09

I’m 100% sold on it. I’m not a small guy, but I’m running 28s at 57f 60r on my Zipp 303S and it’s sublime.

Carbonfiberboy 

The only thing I know about hookless rims is that hooked rims are a relatively modern innovation. Back when I started riding road bikes, hooked rims were unheard of. Everyone ran 1-1/4 X 27" tires on hookless rims. I've blown wire-rim tires off those rims using gas station air hoses, at about 120 lbs. IIRC. So if the article up-thread in post 77 is correct, your tubeless tires won't get hot enough from braking to blow off. Maybe. That article also said that running lower pressure was worse for blow-offs. It's complicated. The idea that hookless is better because you "can" run lower pressures seems funny to me. What's the difference? More likely it is that you "have to" run lower pressures and this is being presented as an advantage. Of course.

I was on a ride featuring a winding high speed descent where a rider rolled their rear sew-up off the rim. Luckily there was a grass verge for comfortable sliding. So that can happen. I don't know what his gluing procedure was, so there's that. I was behind him but he went off so fast it wasn't an issue.

terrymorse 

I hated those old hookless rims. I worked in my parents' shop in the 60s and 70s, and it was so easy to blow off a tire with the air compressor. My ears would ring for the rest of the day.

I don't remember when hooked rims took over (early 70s?), but the sound of a blown tire ceased completely.

Like so many things in cycling, something that was rejected by one generation gets recycled again as a "new improvement".

Lombard

How is it we always go from one extreme to the other. We used to have ridiculously narrow rims and tires. Now everyone is looking for wider, wider and even more wide.

And yes, I get it that hookless rims are a weight weenie thing, because rim hooks weigh soooooooo much they will bring you to a screeching halt!

Racing Dan

None, besides easier (cheaper) carbon rim manufacturing. The claimed benefits seem entirely made up or solutions to non existent problems. On the other hand, the downsides are very real. Diminished tyre retention, leading to a low max pressure of 72 psi (for road tyres) and a limited selection of tyres. No to mention the the fact a hookless rim is the exact same dimension as a hooked one, letting you mount a normal size clincher tyre, creating a very unsafe condition. Of course ppl will claim "user error" and they'd be right, in theory. But, only a trained eye will spot the lack of a hook and only a nerd user will know how to look for a safe tyre. - Imo, the graveyard is waiting for some unsuspecting schmo.

Maelochs

Check out the LarrySellerz thread on seat posts ......

Racing Dan

why?

eduskator

And why exactly it is a disadvantage?

Racing Dan

One disadvantage is, you may not be able to seat the beads without exceeding the safe pressure limit.