Tubeless Question.

Originally posted by thewwkayaker
**My second test with the tire resulted in some interesting findings. Since I have 2 bikes (well 3 really, but two that use tubeless tire and one that I use the most that currently is with tubes on all tires) I don't test the tire out as much as if I had just one bike.

Anyways- 2nd ride was corkscrew-[HTML_REMOVED]pingu-[HTML_REMOVED]pangor. I'm not sure if it was from the jump on pingu (little ramp jump) or from corkscrew but when I arrived at the Badden between pingu and pangor I noticed my tubeless tire had lost and regained bead as there was latex squirts on various spots on my tire casing!!! I noticed that after pangor before empress more of the same and the tire was a little bit flatter - not flat mind you but less air than it had originally.

This makes sense as this is the reason people get pinch flats (the temp. unbeading). The bigger question is - will I flat without knowing it due to small repeated unseatings during a ride causing air to be lost? After X runs on Whistler would I have a flat tire - or if I'm aware of it, would I need to be adding air after so many runs?

Well onto more testing….. only time will tell. **

This is a common finding and is somewhat tire, rim and pressure dependent. If you run any combination of too fat a tire relative to too thin a rim or too low air pressure (particularly if the ground is rocky or you a doing a lot of drops), you may experience this "burping" of air. The tire bead will unseat very momentarily and will reseat. This is much more common with the Stans setup because of the lack of rubber between the bead and the rim. Probably just have to run slightly higher pressure and your problem will be solved. A wide rim will usually prevent this problem even at very low air pressures (ie. less than 20lbs.).

OK - my rear tire went FLAT today on my 2nd ride on Seymour (Pangor - at the end before Slash/Empress). Goop was all over my tire outter casing.

Good news was it was still beaded and I simply reinflated it with a hand pump and it was fine.

I was running 20psi - I like running low pressure and haven't found running higher pressures better in terms of grip.

I rarely rarely pinch flat (3-4 times in 3 years) with a tube so it can't be too crazy to run tires (Mich) that low.

Anyways, my testing continues but with some marks against now.

Just thought I'd give an update in case anyone cares.

I've been using Stan's or UST rims for 3 years now and I can say I'll never use tubes again.

When you mount your tire and inflate it, press in on the bead all the way around the tire. The small burps usually don't occur out on the trail after you do this.

Don't run to low pressure. You have to learn how to use more with tubeless. That's part of the appeal with tubeless: run more air [HTML_REMOVED] get the same grip. I used to be the 15-20psi guy but found I was burping out too much air and going flat. Now I consistantly ride high 20's-35 without any issues whatsoever. However, the thicker the sidewall, the less air you can use.

Grip is also a non-issue. Plus, you'll want more air pressure to keep your tires' sidewalls stiffer. Tubeless with low pressure equals a foldable tire.

The ghetto system seems to work for some, but I've found that with Stan's, I can set it up and ride for almost a season without any problems. The only time I switch my tire is because it's simply worn out. Might be worth the expense for some of the ghetto users to get the Stan's kit.

OK - explain to me WHY tubeless tires grip better. I cannot see the physics at all, certainly not to any real extent that I'll start running say 28psi and have the same grip as a tire running 20psi. Besides, the whole point is (so I read everywhere) that you can run low pressures. I agree that with higher pressures I won't blow the seal - but I cannot see running higher pressures giving me as much grip as low pressure.

I have a set of Mavic XM321 rims and 2.5 Kenda Nevegal/blue goove tires…anyone see any issues with this setup. I really want to try tubeless….but I need to know if this combo will work and if I have to have new tires to do it. (they have 5-10 rides on them)

Originally posted by thewwkayaker
OK - explain to me WHY tubeless tires grip better. I cannot see the physics at all, certainly not to any real extent that I'll start running say 28psi and have the same grip as a tire running 20psi. Besides, the whole point is (so I read everywhere) that you can run low pressures. I agree that with higher pressures I won't blow the seal - but I cannot see running higher pressures giving me as much grip as low pressure.

The way I see it is when you are running a tubed setup you have MORE material (tube) and that material is providing more pressure on the sidewall thus making it stiffer. You take that extra material out of the equation and you can run higher pressure while still getting the same grip. Kinda simple when you think about it.

Here is a quote from the other tubeless thread from baloom….might help you understand the pressure thing a bit more:

I believe it is because the presence of the inner tube adds rigidity to the tire sidewall in a medio-lateral sense (makes the tire taller in profile and stiffer side-to-side). When you remove this extra layer of rubber, this added stiffness is lost…..this is why tubeless tires tend to have a larger "contact patch" even when run at higher air pressures than the equivalent "tubed"tire.

Heh, I also learned that my 2.5 kenda tire that barely fits in my 03 Jr. T's will most likely not fit after I do the no tubes….mabye back tire only.

Originally posted by mudpuppy
I have a set of Mavic XM321 rims and 2.5 Kenda Nevegal/blue goove tires…anyone see any issues with this setup. I really want

That's the first rim I tried, with a Larssen TT tire. I couldn't get it to work, but that's most likely because of me. The rim has a nice lip on the inside, and when I initially took the Larssen off it's bead was almost glued to the rim, .so I would think that it will work with a thin tube.

I just bought a couple 20" tubes, so I'm going to try it again. :)

Originally posted by thewwkayaker
OK - explain to me WHY tubeless tires grip better. I cannot see the physics at all, certainly not to any real extent that I'll start running say 28psi and have the same grip as a tire running 20psi. Besides, the whole point is (so I read everywhere) that you can run low pressures. I agree that with higher pressures I won't blow the seal - but I cannot see running higher pressures giving me as much grip as low pressure.

28 to 20psi is a lot. Probably about 24-25psi would be more realistic.

I think what you're thinking about is why XC racers/riders use tubeless: to make skittish tires grip better in slippery terrain, and to help prevent pinch flats (not to mention less rolling resistance). They generally use less air pressure.

But for DH/FR, you've already got a grippy capable tire that can withstand alot, but a tube inside generally doesn't. You're hiiting rocks so much faster and harder that in theory you should run more pressure. And that's what DH racers/riders usually do: use more pressure.

I don't think they grip any better other than within a couple of PSI or so. I've never had a problem with loss of grip. The only real differences I saw was the lack of rolling resistance and less flats.

However, I'm sure due to the fact that you have less rubber inside would mean that your tire would conform to more uneven terrain. Think of a thin kevlar bead tire vs. a DH tire - which one will "give"? The one with less rubber on the sidewall.

But… I'm saying that you have to learn to use more pressure so as to not roll your tire. You have to compensate for the lack of rubber. A tubeless tire is weaker than one with a tube. Compare each at the same pressure and you'll see a huge difference.

All that said, I've gotten away with about 20psi once or twice.;)

What tires are you using?

Michelins Comp16 2.5 (only 1 tire right now as a test).

So if a thinner sidewall conforms better to the terrain but I then need to increase the psi so it doesn't unbead (and thus conform as well to the terrain) haven't I lost all benefit here?

Dude…stick with tubes….if you are so worried about it than tubes is the way to go. :)

This thread should be sticky….

Originally posted by thewwkayaker
**Michelins Comp16 2.5 (only 1 tire right now as a test).

So if a thinner sidewall conforms better to the terrain but I then need to increase the psi so it doesn't unbead (and thus conform as well to the terrain) haven't I lost all benefit here? **

There's less benefit loss with a thicker sidewall. The greatest benefits of tubeless tires are less rolling weight and less flats, in my opinion. I think overall grip is more dependant upon rubber compound and knobs. You're using the best wet weather tire there is, I can't see why you'd have a problem with grip (unless you're on green wood).

definitely Sticky !
yep

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