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Schwalbe and Syntace unveil dual chamber tyre system
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
Interesting
http://www.bikeradar.com/mtb/news/article/schwal...
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I guess nobody told them about UST.
It's supposed to help lock the bead onto the rim and allow even lower pressures to be run while making sure the tyre maintains its shape and avoiding pinchflats, riim damage and burped tyres.
UST starts to go pear-shaped below 20psi. This is supposed to allow pressures down to the low teens.
I'm all for innovation and trying new things. Look forward to seeing some results.
quite interesting. I'm assuming the quote about being able to get the tyre under 200g has to be a typo though. It would have to weight a fair bit more than a current tubeless tyre with the extra wall in there able to support a high pressure differential
200g extra maybe? Still, it seems confused to me because on the one hand they say it's a tubeless system and on the other they say it will be compatible with conventional tyres. Given the dual chamber there's got to be a barrier between the chambers, which you'd imagine would built into the tyre. The only ways I can imagine it working successfully with a non dual chamber tyre would be 2 inner tubes attached to each other. Even then, having to run the valve from the outer chamber through the inner chamber, whether it's tubeless or tubed seems inherently weak.
Re the weight, it does say that the "system" will weigh less than 200gr, not the tyre.
Similarly, at the top, they talk about a "new dual chamber tyre system" not a new dual chamber tyre.
It would imply that it's separate from the tyre.
I wouldn't be surprised if it was a single tube that sits tight against the rim/beads, with one valve to inflate it, and another valve that goes through that tube and opens into the space between it and the tyre, treating it as a normal tubeless.
As to it being compatible with conventional tyres and rims, that'a bit strange considering for starters that a conventional rim only has one valve hole.
Incidently, has anyone ever got a "snake bite" puncture on a tubeless-run tyre?
I considered that option CyclinAl when I commented previously, but surely the pressure differential is problematic for just one tube when the lower pressure chamber is on the outside and the single tube has little to hold it in place? Maybe such a tube would be somewhere between a tube and a tyre in thickness to compensate? I guess we'll see if it ever gets to market, but I have my doubts it will.
I am pretty sure Michelin/BF Goodrich use it in WRC racing
Hey @cyclinAl, I had a flat at Manly Dam last year & fitted a tube and kept going. When I got home and examined the tyre carefully the sidewall was worn through adjacent to the rim. I think it was the sidewall crushed & worn by a rock against the rim. It was a Specialized S-works The Captain tyre - pretty thin walls. I won't use an S-works tyre again for trail riding.
I imagined it much the same as a 4WD bead locker.
http://www.secondair.com.au/howitworks.htm
- Jeronimo, how about a very light-weight non-stretchable (or moderately) sleeve over that tube. I guess all you want it to do is fill the gap between the beads and protrude enough to stop the tyre squashing against the rim. It doesn't need to distort like a normal tube.
- MrMez's link is probably pretty close to the truth given of course that, in their case, it needs to resist far greater punishment, hence the strap material.
I move the motion that PMBC patent our idea (provided Schwalbe's hasn't beaten us to it!) so it can float on the share market and make heaps of dough and buy a full fleet of top bikes for its members (I mean shareholders!)
- Trim, so technically speaking, it wasn't a "snake bite" flat. I mean, I went tubeless because I had to keep tyre pressure low because of the amount of soft sand where I ride. And of course, as soon as I hit a patch of protruding limestone...
So the notion that tubeless can still get pinch-flats is somewhat disturbing.
Interesting MrMez, that would suggest a stronger casing than a tube.
I have read people suggesting they've snakebited a tyre when running tubeless, but I would have thought burping would be the more common issue, sometimes leading to the former.
I'm wondering what the rolling resistance would be like with tyre pressures below 20psi. Just how much benefit would most riders get from such a system to justify the weight when proper UST does most of this job, and wider rims reduce burping issues? Who beyond gravity orientated riders would run such low pressures?
If our speculation is correct, this "dual chamber tyre system" does not seem to require any specific tyre or rim, which is somewhat odd coming from a collaboration between a tyre and a rim manufacturer. I guess Schwalbe have inner tube experience (presuming they make them themselves), and Syntace have...er...drilling holes in their rims experience! Which they expect you to do yourself if you use an existing rim.
The question is: Is it safe to drill a second valve hole in a rim that wasn't designed for it?
And where do you drill it? adjacent to the existing hole (And risk the hoop opening up)
Or opposite? (And risk the hoop snapping in two)
To which I imagine you'll reply: Where the second bloody valve is!
But still. Is it safe, considering a lot of rims have all unnecessary material shaved off for the sake of weight?
Regarding potential benefits versus rolling resistance, I ride in unusual conditions, where the benefits would indeed outweigh the increase in rolling resistance. But that's because I live there. It's conditions riders would rather avoid. It's fat bike country in fact, but I prefer to ride the bike I ride when I go elsewhere, and it's not fat. Maybe we're underestimating the general benefits and overestimating the cons. Or it could just be something really specialised, bit of a niche product.