Monday, June 1, 2009

MTB Tire Sealant

It's been a while since I last posted, but my weekend of mountain biking in Tahoe has me more motivated. In particular, I feel the need to write a bit about Stans NoTubes Tire Sealant and the Caffelatex sealant. If this is Greek to you, then no need to read on, but if you're a bike geek, then keep reading. :)

I've been running Stan's in various tires for about 2 yrs now and switched to Caffelatex on my MTB 2 months ago since it seemed like the thinner Caffelatex solution might not dry up as fast as Stans, and it also seemed like the foaming action may actually do a better job of sealing the tires.

The Caffelatex was just as easy to set up as Stan's, and I think it does a better job of initially sealing the tires. I started with one wheel with Stans and one with Caffelatex, the one with Caffelatex would lose less air pressure over the course of a few days. Then I switched 'em both over to Caffelatex. So far so good...

However, I hate to report that yesterday I got a 1mm or maybe 2mm cut in my MTB tire (WTB WeirWolf 2.55 LT) and the Caffelatex was not able to re-seal it. I rode it for a mile or so with the solution spraying out all over the back of my bike & leg before my buddies pointed it out to me. Then I stopped, put my finger over the puncture and rotated it into the down position so the sealant was pooled up right above it. It's been my experience that with Stans this will help it seal. Didn't work. It just kept slowly bubbling out. Then I lowered the air pressure to the point that it stopped bubbling out and seemed to seal. I ride at 28 psi generally, but I would guess had to lower it to 15 or 20 to get it to seal. Ok, no problem, we had a long sandy climb coming up, and I figured I could use the traction that comes with lower PSI. I started riding and sure enough, it kept leaking. Ultimately I had to put in a tube after a few minutes of climbing. Grrr...

Compare that with my race at the Sea Otter Classic 2 yrs ago where I put in 3mm cut in a similar tire with Stans with about 2 miles to go (long uphill), kept racing and was able to climb out and finish with about 18 psi in the tire. I took 4th in my category, and changing a tire would have cost me a podium finish at Sea Otter, which was my main go for the season.

I thought I preferred Caffelatex, and even got my local shop to start carrying it, but after this experience, I'm switching back. I don't want to risk having to change a tire at the Downieville XC.

I'm starting to realize that any of these sealants are great for:
- initially sealing a tire with you first mount it
- preventing pinch flats
- allowing you to run lower tire pressure (better traction)
- sealing pin prick punctures that would normally cause a tube to go flat.

However, I do not think they work for sealing bigger holes in tires. Stans has all sorts of videos of them putting nail holes in tires and having it seal right away. That may be the case for nails, but one piece of glass in my Hutchinson Tubeless road tire (2mm hole) and it was toast. The Stans couldn't re-seal it. Likewise, 3mm in a MTB tire and it's toast.

Will I keep running Stans? Absolutely. Does it do everything they claim? ("When properly used, it will seal up to 1/4 inch punctures") Not in my experience.

What I am going to do is put Stans in the tire I punctured over the weekend and see if it does a better job of sealing it since the Caffelatex wasn't able to.

1 comment:

davidbelden said...

Just got a note from the owner of the company that owns CaffeLatex. He has some good points, so I thought I'd post 'em here. I'm going to try out his ideas and see if that does the trick. I hope so! Great to see that they are following their reviews on line and are trying to make sure the product works for all of their customers.

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Hello David,
my name is Alberto and I'm the owner of Effetto Mariposa. I read with interest the post where you report how Caffélatex failed to repair a hole in your tyre. Although we're clearly happier to read positive feed-back, any comment can help us to improve our products and enlarge our knowledge base on the product.
The behaviour of a tyre sealant in case of a flat is not an exact science, as there're so many variables and side conditions that could be the reason of success or failure. That's why I'm writing you, in order to better understand what happened.

The positive elements I got from the analysis of your experience with Caffélatex were that:
- Caffélatex does a better job than Stan's initially sealing the tyres;
- wheels sealed with CL would loose less air pressure than those sealed with Stan's;
- during the flat you had, CL was spraying out of the hole, so it was where it had to be (it's a start!).

You write you punctured (at a pressure around 28 psi), but you just discovered it when your riding buddies signaled it to you, as CL was spraying out of the hole. The fact you didn't "feel" it, means that the pressure hadn't dropped very much, so the puncture hadn't occurred since long... and I guess the sealant hadn't had much time to work. Instead of letting CL 'take care of the business', you reduced the pressure. Although a lower pressure makes it marginally easier for a sealant to coagulate, going to 15 psi doesn't leave much time to the sealant to 'work' before the tyre is too soft (and unridable).
In our experience, the best thing to do in a similar case is exactly the opposite: inflating the tyre will make sure it's still with a rideable pressure when the puncture is repaired.
Caffélatex has been tested also in high-pressure applications (RoadTubeless) and it has behaved very well repairing punctures with pressure much higher than mtb's ones.

Another thing we learned during the extensive field-test that led to the definition of CL formula, is that 'holes' are not simple 2-dimensional entities (often reduced to a 'single-dimensional' size, 1mm, 2mm etc.), they're rather complex items: a small hole from the outside might hide a bigger damage on the inner side, or vice-versa. That's why sometimes a sealant seems to have 'paranormal' powers and repair what looks like a big 'scar'... that is reducing to a small cut on the inner side of the casing. Some nasty little holes, on the other hand, take ages to seal, because the damage is not as small as it seems.

Beside major damages, we always managed to have Caffélatex repair punctures up to 3mm. Most of the times it was fast, sometimes we had to inflate the tyre once after it went almost flat (and got our share of syntethic latex sprayed around...), but during the tests we never had to put inner-tubes inside tyres treated with Caffélatex.

If you still didn't repair that Weirwolf, I'd like you to have a look at the puncture from the inside, to see how it looks like. It would also be interested to see what happens if you don't repair that tyre and simply let CL work, after taking the pressure up to 35 psi: I wouldn't be surprised if the hole is sealed for good before the pressure drops below 20 psi.

Do not hesitate to contact me for further questions, thanks for your comments and best regards.
Alberto

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Alberto De Gioannini