Yet another article on a tubeless tire blowing off the rim.

[Clancy]

Interesting article on yet another tubeless tire blow-off. But Zenn theorizes the rim, not the tire, maybe at fault and being set-up tubeless was not part of the issue. Also interesting, given the recent tread on Challenge tires, that he turned to their engineer for explanation.

I’m not sure what to think anymore.

Are aluminum rims with tubed tires the only way to go? Or sew-ups which I’m not doing.

https://www.velonews.com/2019/09/bik...yrenees_500757

[weiwentg]

Well, the article did say that some carbon rims can have sharp edges on their bead hooks. They're supposed to be sanded off after the rim is molded (the molding process inherently will leave sharp edges). The guy who Zinn consulted blames the incident on a sharp edge or burr that someone missed. We could just inspect all carbon rims for burrs, no?

That said, the engineer in question works for Challenge (note: the tires in Zinn's article are Conti, not Challenge), and Enve has had a beef with Challenge, as discussed here on the forum. Some people are like, yeah, Challenge tires suck. On the other hand:

Originally Posted by Nooch

i feel like this is enve saying "oh hey, we may not catch every burr on our rims so be safe and don't use something that's somewhat more delicate -- let's blame the tires, not the rims..."

Originally Posted by ergott

It would be nice if they would simply finish the edges of their rims off. They are the only rim I've recently seen with sharp edges. Rims like Boyd, Nox, and FSE are all finished of with much higher quality.

I'm not doing carbon

Originally Posted by ergott

It would be nice if they would simply finish the edges of their rims off. They are the only rim I've recently seen with sharp edges. Rims like Boyd, Nox, and FSE are all finished of with much higher quality.

No personal dog in the fight for me.

[Hindmost]

If I understood the article correctly, it wasn't so much blow off as sidewall failure.

[R3awak3n]

I have had that exactly rim setup tubeless for a bout 1500 miles and has been great but now it has got me second guessing. Not sure his exact pressures but 6.5 bar is 95 PSI, that is WAY too much for tubeless. A lot of manufacturers don't recommend over 60PSI and it kind of makes sense.

[saab2000]

I've never had this happen but a buddy had a tire just the other day blow off a rim. I'll have to get details. It was a tubeless tire and his initial impression was a cut of the cords in the bead. Hooked, aluminum rim. He's not on this forum (or any other) but it extremely detail-oriented.

Personally, my only tubeless experience is with Pacenti SL25 rims and the Panaracer Gravel King 38mm herringbone tread tires. I use Finish Line sealant and run them around 40-42 PSI. This is a hooked rim. Initially I think I set them up with around 50-60 PSI and thought this absurdly low because I'm a roadie and think higher must be better but I know better because I run my 23s on wide road rims as low as 85-90 and 25s as low as 75-80 and love them and I'm no waif. This pressure was far too high.

The 38s at 40ish seem just right in terms of ride quality but I wish the rim were wider. Very small changes in pressure seem to affect ride quality or handling quality quite a bit more than these single PSI changes in narrow tires on narrow rims.

Anyway, it's not about all this but the other factors in the equation and safety. The hookless vs hooked rim is interesting and the linked article (and further links) about tire shape are very interesting and mesh with my own experience than wider is better when it comes to the resulting tire shape.

The folks I've talked to about hookless see no safety compromise as long as pressures stay reasonable and since my own experience with 40-42 PSI is good I'd say this is accurate. I'm experimenting with wider tires and lower pressures and will be trying some hookless rims in the spring. It seems even the rigidity of the casing is important.

Safety is always the primary concern and until now tires blowing off a rim has been an extreme rarity. I guess the tubeless thing brings its own real challenges. It seems to be documented more and more of late. That is disturbing.

[pbarry]

We should all inspect for Burrs. They are a dangerous lot.

[berserk87]

Originally Posted by Hindmost

If I understood the article correctly, it wasn't so much blow off as sidewall failure.

That's the most significant point that I took from the article. He states:

"I think tubeless is a red herring here. I believe what happened to you could have also happened with a lightweight clincher tire with an inner tube. It sounds like the rim’s bead hooks cut enough of the threads in your tire casing that it blew."

And a nod to "pbarry" for one doggone fine historical reference!

[dddd]

The article quoted the tire guy mentioning a "Shafer's strip", which I had always read as a chafer strip, so hopefully this may be clarified.

Tires without the durable protective cloth strip over the bead area can have the casing threads severed or weakened by the sliding of even a plastic tire iron, so can be a source of this sort of blow-out.
Even the tires with thick rubber over the bead area can have some length this rubber sheared right off and the threads damaged at the same time, just by the sliding of the lever OR the pulling-off of the partially-freed tire!

The edge of even an alloy rim can pinch and "scissors" the threads as the partially-dislodged tire bead is pulled free of the rim, so I use caution not to exacerbate this tendency when dealing with a tire bead that needs force to fully remove.

[Clancy]

Originally Posted by Hindmost

If I understood the article correctly, it wasn't so much blow off as sidewall failure.

My takeaway as well but also the sidewall failure was caused by a sawing action from the carbon rim, or so Zenn theorizes.

[yinzerniner]

Originally Posted by pbarry

We should all inspect for Burrs. They are a dangerous lot.

Only when in Weehawken at dawn!

But for real, take a look at this latest screed from Enve. A whole lot of marketing mumbo-jumbo and blame-shifting b.s. IMO.
https://www.enve.com/en/journal/behi...ho-theyre-for/

[RobJ]

Originally Posted by yinzerniner

Only when in Weehawken at dawn!



But for real, take a look at this latest screed from Enve. A whole lot of marketing mumbo-jumbo and blame-shifting b.s. IMO.

https://www.enve.com/en/journal/behi...ho-theyre-for/

Seriously? Where are they blame shifting? Seems to me like a lot of common sense explanation on rim/tire design and the ins and outs of proper tubeless. Since Enve has both hookless and hooked rims they’re not pushing any one agenda plus other manufacturers have hookless, so it’s not unique to Enve.

Looking for new wheels I have read a ton of the manufacturers tech info and I don’t see any of this as marketing. More people should read these type of things and be better informed so they don’t go running around placing blame for their own mistakes.

A major sidewall cut is not “a tubeless blowout”. Sensationalism. Just like the hocus pocus with latex tubes originally.


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[colker]

Tubeless is worth the risk and pita on mountain biking. If you ride in cactus country there is no other way... On a road bike i will go w/ tubular before tubeless.

[9tubes]

Originally Posted by RobJ

Seriously? Where are they blame shifting? Seems to me like a lot of common sense explanation on rim/tire design and the ins and outs of proper tubeless. Since Enve has both hookless and hooked rims they’re not pushing any one agenda plus other manufacturers have hookless, so it’s not unique to Enve.

Looking for new wheels I have read a ton of the manufacturers tech info and I don’t see any of this as marketing. More people should read these type of things and be better informed so they don’t go running around placing blame for their own mistakes.

A major sidewall cut is not “a tubeless blowout”. Sensationalism. Just like the hocus pocus with latex tubes originally.


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Last winter there was a kerfuffle in the industry when riders were having catastrophic failures with the bead being cut. Enve rims were involved and that company issued a press release that blamed the tire manufacturers for poor tires. The tire manufacturers noted that the problem didn't occur on non-Enve rims. Challenge examined recent Enve rims and said there was a sharp moulding flashing on the bead, and the bead was not built to ERTO standards. Challenge and Vittoria recommended not using Enve rims with any tire. This seems to be a problem only with late-2018 and 2019 rims.

Since Enve didn't see it as their problem I don't expect a change but I don't have the most recent info on this.

http://www.bicycleretailer.com/produ...g#.XYp_8i-ZN-U

https://forums.roadbikereview.com/wh...in-367481.html

[Davist]

the recommended tire pressure chart is interesting, down to 46psi (180lb me) for 28s on gravel. I run low pressure (mostly 75 rear 65 front) on my 28s but this seems like rim damage levels (IF you weigh 90lbs it's 26psi!) https://www.enve.com/en/tirepressure/

[kingpin75s]

Originally Posted by Davist

the recommended tire pressure chart is interesting, down to 46psi (180lb me) for 28s on gravel. I run low pressure (mostly 75 rear 65 front) on my 28s but this seems like rim damage levels (IF you weigh 90lbs it's 26psi!) https://www.enve.com/en/tirepressure/

Chart looks ok to me. I weigh 140lbs and tend to run my 35c tires at 35psi on gravel. Chart matches my experience well. YMMV and all that.