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My NST® 'Tubeless' system WILL work,oh yeah! (and need tips) (7 posts)
|  My NST® 'Tubeless' system WILL work,oh yeah! (and need tips) | Cloxxki
Mar 24, 2002 6:30 AM | | NST® : Non-Stratchable Tube
Designed to sit in between tire beads, pressing them firmly (at rim's max psi) against the sidewalls.
Actually it should be calles STT® : Shrinking Tube 'Tubeless'.
I just unwrapped a Tufo S3 Lite <145g time trial/track tubular. (I happen to be distributing Tufo in Europe). Yhis one is 18mm wide, and of course made for 700c (622mm) rims.
I was a pain to fit on a 700c clincher rim, I'd have to force-stretch it first, and the rim I have here is only 20mm wide. Also available was a 26" Bontrager Valiant. Putting the valve though the designated hole, it became apparent how big the difference between 700c (622mm) and 26"(559mm) really is. The tubular was really 2" too wide.
So, I inflate to 8 bar (max is 15bar), and the S3 is now snugly on the clincher rim. Shrunk 2 full inches!
Imagine this: a 15mm (or thereabouts) tubular with minimal rubber protection on it, designed to fit very loose (deflated) around a rim (either 26" or 700c). Mount like a regular innertube, inside a tire. Inflate the ST/NST to some 5 bars (or close to max. bar the rim will take), the ST will shrink and cling on to the rim very firmly, thereby forcing the beads of the tire against the rim. A nice clearcoat layer or latex on any kind of bead before mounting should already make for an almost (of even completely) airtight fit already. The tire is still flat.
Now come the more difficult part (I need your help here). To inflate the tire as almost-tubeless, we need to have either a seperate valve, or an overflow valve in the ST, letting air over for instance 5 bar to flow to the tire-compartiment. A seperate valve may be hard to get air through, as the ST is already firmly pressing on the rim surface. Maybe a the separate valve could be built into the ST, just running though it without connecting to the chamber inside it?
Alright now. The tire/rim seal may already be perfect with the inflated (N)ST, but we still need to seal the regular tire of small leaks in the tread and of course prevent flats. Latex can be inserted while mounting as with Stan's, but also through the seperate valve should we go this route. I think the latter option would be less messy, especially when combined with Michelin's technique of blowing a latex/gas mixture in with a cool device.
The (N)ST would be much smalle than the smallest track tubulars I know of (Tufo's start at 18mm). Note : the lightest, very ridable, 700c*18mm tub is <110g (!!!). This is with morerubber protection than a NST will ever need. Yes, the price is outrageous, but so is UST technology. We wouldn't need Tufo's hi-tech tread material on it, just a nice protective layer without any riding characteristics, let alone mileage. How much would a 26" 13-15mm (what's ideal?) ST weigh? 60-70g? That's not much more than either Stan's or Eclipse, though a lot more expensive. I think the cost will be worth it though, I get the feeling it might just be a superior system.
If it really works, perhaps pretty stupid of me to tell al these detils about it, but I don't think I have the time, technical knowlegde, energy or cash to even get a working prototype. Taking the credits from you guys,a nd being able to ride it myself would be enough pay for me. I may try to concince my contacts at Tufo to make me a prototype, but it would probably cost me, and they will feel it endangers their present market.
Please shoot at my comments above, what are the flaws? what to change/improve? what do you think of it all, and should I still try to get it to work? What would a customer pay for it, if it works the way I expect it to?
Thanks for all your responses,
Cloxxki |
| why so complicated,what for,...? i don`t get your point... | nino
Mar 24, 2002 7:11 AM | | why would you want another "tube" inside the tubeless tire?because you feel the tire isn`t locked secure enough on the rim?
just wait until the Eclipse is on the market-it is designed to make tires stick to the rims.unlike Stans rimstrip that covers the whole rimbead including those "hooks" that tires need to get a hold which is no good.
we have yet to find a tire that doesn`t mount easily at the first try...to dismount tires on our system you actually need some force to get the tire unseated from the rim! |
| well... (and an update) | Cloxxki
Mar 24, 2002 8:16 AM | | Indeed, no blow offs, even at zero psi, and dead easy mounting. Forgot to mention that the ST would also help prevent pinchfalts a bit, providing a small cushion.
Don't know if the effect on the slightly smaller tire air volume will be noticable in the ride, and whether it will be positive of negative.
Oh, I'm really looking forward to hearing how the Eclipse system will work, technicaly. I'm sure it will be good enough to try out, at least as good as Stan's innovative strips.
Update on my little idea:
I just mounted the (way too big) 700c tubular inside a Fast Fred 2.35", on an ancient Araya VP-20 rim, that measures a full 26mm wide. At 10 bar, the fit was pretty snug, but the 18mm width of the ST was still too great to slide in between the beads. Of course the shrinking force was not so great due to the too big initial size of 700c.
Seems like 12-13mm would be well enough width for an ST on a standard mtb rim.
Now I'm pretty sure an ST sould be a perfect fit around the rim before inflation, while being narrow enough to allow easy installation of the beads next to it. Inflating the ST would immediately press the beads on the rim, while the shrinking force keeps it from popping out/off.
Inflating the tire first, and then the ST is also an option, but doesn't seem to make sence, as long as the inflation of the ST first doesn't make the bead to mis-seat on the rim. |
| Oh man... | eric wictor
Mar 24, 2002 10:52 AM | | This is pushing it, Cloxxki.
To get air, you could just drill another valve hole in the rim, but all this weighs as much as a normal inner tube. Might as well go UST if this is the way to get it really right.
Also, maybe this will make me sound like an @-hole, but why don't you just ride your tires at normal pressures? Your Fat Fred will not fly off the rim as easily then, I think.
If Eclipse will work for urban and trials stuff too, I'll give it a go, but for the moment I've had it with tubeless. Too much goofing around. ;) |
| Hmmm, if that would work, my system is a failure already. | Cloxxki
Mar 24, 2002 11:50 AM | | I claim the rim/bead seal to be almost perfect already after inflating the ST. If that is true, how is air from the extra tubeless valve going to reach the tire? The extra valve would only work if at first you'd inflate the tire old-style (no help from the ST system there), and only after that inflate the ST to secure the fit, covering the extra valve that you used for initial inflation. Adding air later would be a pain, I'm affraid.
Okay, this settles it, The ST will have to feature a built-in extra valve running though it, opposite to the other one, to allow inflation of the two compartiments, in either order you prefer.
Total weight, compared to Stan's strip, would not have to be more than 30g, still about level with a normal ligher tube, but with much higher performance: much less messy inflation, no need for any inflating power, since the ST is a tube and seals the bead/rim intersection first.
And most importantly, the very stiff mounted beads will aloow for a predictable and stable rides. Because everytime a bead is pulled of the rim, tire stability is being compromised, losing air in the event is only a secundairy effect. If it were safe, we'd probably all like to ride at low pressures, especially on bumpy trails. Just as long as sideways movement under cornering is not so much that it will feel like rear-wheel steering. Having an almost tubeless will may be expensive, I'm pretty sure it will be great for racing.
I may try to convince Tufo make me a +/- 13mm wide prototype, designed to shrink a lot, but survive it till at least 7 bar, at minimal weight. Their 650c mold should be a pretty nice size to start with. Biggest problem would be finding a 13mm innertube.
I'll try this only after I hear about Eclipse of course, ST will have no point if that is already working reliably enough.
Still the idea is pretty cool, admit it! :-)
Oh, what about this one?
Buy a UST rim, weight and strenght are irrelevant. Mount stan's strip, then brush some special bonding-glue on the sides. Mount the tire with very clean beads. Preferably one that has been mounted latex-tubeless before. Inflate. This should be cake, thanks to the glue. Not latex or soap!
Now the trick : fix some wires on the rim to heat it up. Enought to have the bead and tire bond permantly, the butyl melting onto the beads. Temperature should not affect the tire's integrity. You now have a Lovetires-style semi-tubeless system that will only need latex or slime to seal punctures. Choice of goo is therefor much broader.
Too much effort? Would work great for lose-fitting tires I bet... |
| Jan-Gerrit,you clearly have too much time on your hands today... | AZ-X
Mar 24, 2002 12:17 PM | | Why don't you go for a ride and clear your head a bit... ;o) |
| I know, I know... | Cloxxki
Mar 24, 2002 1:25 PM | | Socializing and alcoholizing at last night's party made this day to be a very lazy one. I should have gone for a 3-4 hours ride, to try catch up after my BAD training over the last two weeks. I will pay the debt next race, april 1st. With my good starting position I will be able to join the lead early on, and then find myself gasping for air trying to keep up. My first wsports win will have to wait some more...
But hey, name me 3 things cooler than just talking about bikes?
1. Biking itself and 2. women, in any particular order, preferably a combination of both. Too lazy for the first, and the second is planned for coming tuesday. Third is something only granted to the very happy few, but I'll start working on that once the time is right :-) |
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