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Old 04-08-14, 11:04 AM   #1
waynesulak
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Beadless tubeless rims

Given the discussion of tubless blowouts in this thread:

Schwalbe One update (tube and tubeless)

I noticed that Enve now makes tubeless rims with a bead or "beadless. Below is a graphic from their web site showing the design.



I don't understand how using a rim without a bead will help keep a tubeless tire on the rim. I can see advantages in manufacturing. Note the text in the graphic states that this design helps avoid unpredictable air loss.
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Old 04-08-14, 11:49 AM   #2
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Originally Posted by waynesulak View Post
Given the discussion of tubless blowouts in this thread:

Schwalbe One update (tube and tubeless)

I noticed that Enve now makes tubeless rims with a bead or "beadless. Below is a graphic from their web site showing the design.



I don't understand how using a rim without a bead will help keep a tubeless tire on the rim. I can see advantages in manufacturing. Note the text in the graphic states that this design helps avoid unpredictable air loss.
First, it appears that this is for mountain bike wheels, which run at much lower air pressure. The issue with running low pressures on tubeless tires, as I understand it, is more keeping the tires from "burping", than it is keeping the tire from blowing off the rim.

From the diagram, you can see how beadless could make a better air seal between the tire and the rim, by avoiding gaps at the hook bead.

Also realize that automotive tires are beadless, and they stay on ok.
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Old 04-08-14, 01:26 PM   #3
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Originally Posted by merlinextraligh View Post
First, it appears that this is for mountain bike wheels, which run at much lower air pressure. The issue with running low pressures on tubeless tires, as I understand it, is more keeping the tires from "burping", than it is keeping the tire from blowing off the rim.

From the diagram, you can see how beadless could make a better air seal between the tire and the rim, by avoiding gaps at the hook bead.

Also realize that automotive tires are beadless, and they stay on ok.
I think car tires do have a bead, just not as pronounced.

I don't get the Enve design either. Unless a tire was designed for it specifically, don't all bike tires have some sort of bead?(Tubulars excepted).
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Old 04-08-14, 01:49 PM   #4
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I think car tires do have a bead, just not as pronounced.

I don't get the Enve design either. Unless a tire was designed for it specifically, don't all bike tires have some sort of bead?(Tubulars excepted).
Ok, it probably would have been more correct to say that automobile wheels don't have hook beads.

Old clincher wheels did not have hook beads. Clincher rims only started having hook beads with the move to high pressure clinchers. That's why clincher tires used to have maximum inflation pressures like 75psi.

http://www.sheldonbrown.com/harris/tires/630.html
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Old 04-08-14, 04:27 PM   #5
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Originally Posted by merlinextraligh View Post
First, it appears that this is for mountain bike wheels, which run at much lower air pressure. The issue with running low pressures on tubeless tires, as I understand it, is more keeping the tires from "burping", than it is keeping the tire from blowing off the rim.

From the diagram, you can see how beadless could make a better air seal between the tire and the rim, by avoiding gaps at the hook bead.

Also realize that automotive tires are beadless, and they stay on ok.
I understand your point about lower pressure. Stiffer mountain bike tires also might hold their shape and help prevent bow offs.

I think the second point would apply only if the tire and rim were not compatible. I use tubed tires on "tubeless compatible" Velocity A23 rims and my tires kelvar bead fits very tightly in the section below the hooked bead. I can deflate the tire completely and both beads remain firmly in place. To remove the tire I have to use my thumbs pushing sideways in on the sidewalls to get the bead to come out. This seems to offer a much stronger seal than the graphic indicates for a hooked bead. One nice feature of this set up is that the tires line up perfectly when inflated. There are no adjustments needed to center the tire on the rim. These are lightweight road tires designed to be used with tubes so maybe stiff tubeless mountain bike tires would seal less well?
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Old 04-09-14, 06:16 AM   #6
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Enve's not the only one; Specialized also has a beadless MTB rim. Their stated reason for doing it may be a little more candid: ease of manufacturing carbon rims, without the bead. They also point out that automobile tires, motorocycle tires, don't have hook beads and bicycle tires from the 60's didn't have them.

Up Close with Specialized's Beadless Clincher

Looking at the history of clincher rims, I think this is still going to be an MTB thing, and likely won't spread to road tires. Road bike rims were straight sided, no hook bead, until we went to higher pressure clinchers. So the higher pressure in road bike tires may still require hook beads, particularly for a safety margin.
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Old 04-09-14, 08:00 AM   #7
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Ibis also has hookless bead MTB rims. "The design is intended to be lighter".

Ibis hopes to redefine 'wide' with new mountain bike wheelsets - VeloNews.com
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Old 04-09-14, 08:09 AM   #8
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I have wide hookless carbon rims, and run supple high volume/low pressure road tires with and without tubes. The tires are designed for tubes and hooked rims, yet they seal securely when installed tubeless on these rims. While hookless construction does create a stronger rim edge, it isn't the entire story of improved tubeless security. Derby rims have a bead lock that discourages the tire from unseating if deflated, it also cradles the tire bead for improved seal. Greater force is required to move a tire bead over Derby's bead lock than to unseat a tire bead from a rim hook. Carbon rims are formed in a machined mold resulting in accurate & consistent dimensions, extruded alloy rims have a wide range of tolerances.

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Old 04-09-14, 09:38 AM   #9
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I have wide hookless carbon rims, and run supple high volume/low pressure road tires with and without tubes. The tires are designed for tubes and hooked rims, yet they seal securely when installed tubeless on these rims. While hookless construction does create a stronger rim edge, it isn't the entire story of improved tubeless security. Derby rims have a bead lock that discourages the tire from unseating if deflated, it also cradles the tire bead for improved seal. Greater force is required to move a tire bead over Derby's bead lock than to unseat a tire bead from a rim hook. Carbon rims are formed in a machined mold resulting in accurate & consistent dimensions, extruded alloy rims have a wide range of tolerances.

Very interesting

What tires and width, Hetre 42mm ?
Pressure that you run them?
Sealant used?
Team weight?
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Old 04-09-14, 09:48 AM   #10
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Hetre 42mm nominal (47-48mm mounted), Pari-Moto 38mm nominal (43mm mounted)
33 R, 30 F
Orange Seal
Single rider only, 213 - 217 bike & rider.
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