Road tubeless and burping

[Mark McM]

There's an interesting discussion in the latest Velonews 'Technical FAQ' (https://www.velonews.com/2019/07/technical-faq/technical-faq-tubeless-road-tires-glove-loops-e-bike-power_495710) column regarding burping in road tubeless tires. It is discussed that burping of high pressure, low volume (road) tires is more likely to result in a completely flat tire than on low pressure, high volume (MTB) tires, and how this can be safety issue in some circumstances. Jan Heine wrote a blog post titled "The trouble with 'Road Tubeless'" (https://janheine.wordpress.com/2017/05/29/the-trouble-with-road-tubeless/) about this same issue. In a recent edition of his Marginal Gains podcast (https://marginalgainspodcast.cc/ask-josh-anything-003/), Josh Poertner of Silca interviewed representatives from Maxxis tires and Stan's No Tubes, and they discussed that there are not yet any universal standards for road tubeless tires and rims, and aren't likely to be for some years.

Tubeless tires are common on autos and motorcycles, but there are well developed standard that the tire and rim manufacturers adhere to, to guarantee compatibility. (Analogously, ski boot and bindings provide safe retention because the boot and binding manufacturers adhere to the same DIN standards). With so many different tire and rim/wheel makers using their own standards, how can we be assured that our combination of road tubeless tires and wheels are safe?

[unterhausen]

I thought all the tubeless ready rims had that ridge that Zinn talks about. I'll have to look.

My Maxxis tires have been the hardest to mount, which I also take as a good indication they are going to burp easier, although I haven't had any problems with the 40mm Maxxis I have been riding. Panaracer seem very good in comparison.

[yinzerniner]

There's an interesting discussion in the latest Velonews 'Technical FAQ' (https://www.velonews.com/2019/07/technical-faq/technical-faq-tubeless-road-tires-glove-loops-e-bike-power_495710) column regarding burping in road tubeless tires. It is discussed that burping of high pressure, low volume (road) tires is more likely to result in a completely flat tire than on low pressure, high volume (MTB) tires, and how this can be safety issue in some circumstances. Jan Heine wrote a blog post titled "The trouble with 'Road Tubeless'" (https://janheine.wordpress.com/2017/05/29/the-trouble-with-road-tubeless/) about this same issue. In a recent edition of his Marginal Gains podcast (https://marginalgainspodcast.cc/ask-josh-anything-003/), Josh Poertner of Silca interviewed representatives from Maxxis tires and Stan's No Tubes, and they discussed that there are not yet any universal standards for road tubeless tires and rims, and aren't likely to be for some years.

Tubeless tires are common on autos and motorcycles, but there are well developed standard that the tire and rim manufacturers adhere to, to guarantee compatibility. (Analogously, ski boot and bindings provide safe retention because the boot and binding manufacturers adhere to the same DIN standards). With so many different tire and rim/wheel makers using their own standards, how can we be assured that our combination of road tubeless tires and wheels are safe?

In short - we can’t at least not yet.

And there has been a agreed upon standard burn it hasn’t been fully implemented yet. It’s the mavic ust road standard. Stan’s and maxxis haven’t joined one yet for both design and economic concerns. But all the other tire and rim manufacturers have begun to adhere to it.

Many “tubeless” rims don’t have the bead shelf for retention, probably because there’s no standard for tire bead shape and thus it’s more difficult to ensure ease of installation with a wide range of tires. The sooner a standard is set the better off everyone will be.

[MikeD]

I thought all the tubeless ready rims had that ridge that Zinn talks about. I'll have to look.



My Maxxis tires have been the hardest to mount, which I also take as a good indication they are going to burp easier, although I haven't had any problems with the 40mm Maxxis I have been riding. Panaracer seem very good in comparison.


No, many tubeless road rims don't have the ridge. My DT 460 tubeless rims don't. Welcome to the world of lack of standardization in the bicycle industry. Mavic UST road is the only standard, but using another brand of tire other than Mavic UST makes it non-standard.

Personally, I think road tubeless doesn't work that well. Pressures are too high for sealant to work reliably and the stuff sprays all over the place when you get a flat and it's hard to remove. If you don't get a lot of flats, it's not worth it.

I thought burping was a low pressure phenomenon; really not applicable to high-pressure road tires.

[Mark McM]

I believe my tubeless ready Hed Jet+ rims have these ridges mentioned. But Zinn points out that the rim bed is covered by tape (to seal the spoke holes), which smooths out the edges of the ridge. He further says:

Instead, having shiny, slippery sealing tape smoothing the rim contours under the tire bead, lubricated by slippery tire sealant, seems to me to offer significantly reduced resistance against the bead moving inward and burping air in the case of hard cornering, especially at the lower pressures that tubeless makes possible by eliminating the inner tube and hence pinch flats.

[Mark McM]

I thought burping was a low pressure phenomenon; really not applicable to high-pressure road tires.

I don't use tubeless MTB tires, but I ride with many people that do. I've witnessed MTB tire burping on many occasions. But on MTB tires, it usually lets out only a portion of the air, and is more of an annoyance than a safety issue.

On road tires, burping appears to be much less common. But when it does happen, it may result in a greater pressure loss (and possibly complete deflation). If it were to happen at speed, it could be safety issue.

[Peter P.]

With so many different tire and rim/wheel makers using their own standards, how can we be assured that our combination of road tubeless tires and wheels are safe?

Rim and/or tire manufacturers will have to pair up to design, manufacture, and subsequently ADVERTISE that their equipment is compatible with each other.

Endorsement of one brand by another should boost sales, and presumably solve the problems. Advertising your combination is "burp-proof" must have some value.

P.S. I got a pinch flat on my tube-tired mountain bike this morning, riding the road to the trail. I'm still not switching to tubeless, dammit!

[Mark McM]

Rim and/or tire manufacturers will have to pair up to design, manufacture, and subsequently ADVERTISE that their equipment is compatible with each other.

Endorsement of one brand by another should boost sales, and presumably solve the problems. Advertising your combination is "burp-proof" must have some value.

This approach might actually end up back-firing. By saying that certain tire and rim combinations are known to be compatible, it implies that other combinations are not compatible. The implied incompatibilities might serve to discourage, rather than incourage sales.

Also, tire and and wheel manufacturers may not want to commit to one proprietary standard over another, because there is always the chance that side you picked ends up on the losing end. Examples of this include the Betamax vs. VHS battle (followed by a smaller batter between DVD-HD vs. BluRay), and the Profil vs. NNN cross-country ski boot/binding war (the companies that had been supporting Profil have recently conceded defeat, and the industry has universally shifted to the NNN system).

While some tire/wheel companies will cooperate on compatibility in the interim, what is really needed is a universal standard, as has been achieved in other industries (like auto & motorcycle tires & wheels).

[fogrider]

I thought all the tubeless ready rims had that ridge that Zinn talks about. I'll have to look.

My Maxxis tires have been the hardest to mount, which I also take as a good indication they are going to burp easier, although I haven't had any problems with the 40mm Maxxis I have been riding. Panaracer seem very good in comparison.

I've been using Maxxis Ramblers in a 38mm for a couple of years and had no problem mounting them...I would not say they are not road tires but have been a great balance for road and gravel use.

[weiwentg]

I've been using Maxxis Ramblers in a 38mm for a couple of years and had no problem mounting them...I would not say they are not road tires but have been a great balance for road and gravel use.

Actually, Heine kind of addresses that point in his blog post (Mark provided the link already). He stated that road cycling uses very high pressures relative to other tubeless applications on bikes, and on motor vehicles as well. That's a lot of pressure forcing the tire beads outwards, so we're very sensitive to rim fit. He feels like you shouldn't use more than 60 PSI in any tubeless tire.

And your Ramblers probably don't even need anywhere near 60 PSI. So no surprise if they're fine for you!

The thing is, if you are using 25-28mm road tubeless tires, that's a potential problem, and you're going to be more sensitive to rim fit. I suspect most riders need at least 60 PSI even in 28mm tires.

[MikeD]

Actually, Heine kind of addresses that point in his blog post (Mark provided the link already). He stated that road cycling uses very high pressures relative to other tubeless applications on bikes, and on motor vehicles as well. That's a lot of pressure forcing the tire beads outwards, so we're very sensitive to rim fit. He feels like you shouldn't use more than 60 PSI in any tubeless tire.



And your Ramblers probably don't even need anywhere near 60 PSI. So no surprise if they're fine for you!



The thing is, if you are using 25-28mm road tubeless tires, that's a potential problem, and you're going to be more sensitive to rim fit. I suspect most riders need at least 60 PSI even in 28mm tires.


I'm not buying the 60 psi bit. Rene Herse/Panaracer tires have weak, stretchy tire beads. Hutchinsons for example, don't.

[Davist]

Actually, Heine kind of addresses that point in his blog post (Mark provided the link already). He stated that road cycling uses very high pressures relative to other tubeless applications on bikes, and on motor vehicles as well. That's a lot of pressure forcing the tire beads outwards, so we're very sensitive to rim fit. He feels like you shouldn't use more than 60 PSI in any tubeless tire.

Not 100% sure, but I think on highway trucks use ~100psi and tubes. Might it be for this reason?

[Mark McM]

Not 100% sure, but I think on highway trucks use ~100psi and tubes. Might it be for this reason?

Large aircraft can have over 200 psi in their tires. While inner tubes were used in the past, large aircraft have been moving to tubeless tires in the last few decades. But you can bet that these tires have been well tested and qualified, and that rigorous standards for tire & wheel compatibility have been developed.

[bitpuddle]

The person who asked that question said he was using Hed Ardennes rims. He didn’t mention if the they were newer “plus” rims or the older C2 ones.

Older C2 rims are not tubeless compatible; they are a conventional clincher design. Only the newer Plus rims are. Hed is clear about this. If he was running high-pressure (>60psi) on C2 rims, it was a disaster waiting to happen.

[dddd]

Actually, Heine kind of addresses that point in his blog post (Mark provided the link already). He stated that road cycling uses very high pressures relative to other tubeless applications on bikes, and on motor vehicles as well. That's a lot of pressure forcing the tire beads outwards, so we're very sensitive to rim fit. He feels like you shouldn't use more than 60 PSI in any tubeless tire...

The thing about air forcing tire beads out of place is an indirect correlation.

Actually, it is the tire casing tension which applies force to the tire bead, and this tension is proportional to not only the air pressure, but also to the cross-sectional width of the tire.

So 60psi in a bicycle tire applies a relatively small tension in the tire casing fabric, and hence on the tire's beads, as compared to the much larger-section tires used at lower air pressures on larger vehicles.

So I think that it is the lightweight construction of bike tire beads along with the minimalist rim sidewall height and retention nubs that make bicycle road tires more sensitive to tolerances and possible dislodgement from their similarly lightweight rims.
Because if the bead had a much tighter fit on the rim (without causing damage during installation or removal of the tire), then the bead would be more secure but the entire rim and tire would end up having to be a lot heavier.

And kudos to Mavic for choosing to not market tubeless tires and rims that are not wedded by related standards, and for development of same.

[bigbill]

Is burping road tubeless a common occurrence? I've been riding it with 25's for two years with lots of other people who are also road tubeless. The only issues I've seen are people who ran tubeless on non-tubeless rims.

Saw quite a few rolled tubulars back in the day. Mostly due to operator error.

[tombtfslpk]

Apparently I'm lucky to be alive today. My wife and I rode 30ish miles yesterday, with over 4000 feet of climbing (and descending). I was using those rims from the "pioneer of road tubeless" mentioned in the "article", at 85PSI :eek:. I suppose that the confidence buoyed by several thousand miles, in ALL conditions, without burping, on this particular rim/tire combination is simply one of those situations where fools are given a pass.
Maybe it's because my personal findings don't mimic the knowledge of an "expert"....like those tires with tubes that have blown off rims when I have been inflating them. I suppose my tubes didn't know they couldn't "stretch any farther".
I can appreciate that a tire manufacturer/distributor needs to err on the side of caution, and the purchaser needs as many pertinent facts as possible to make well informed decisions. But spreading opinions as fact.....let's leave that to the "news" networks.