When I got my first mountain bike, I swore by putting Slime in the tires. It worked great with sealing the little thorn punctures. However, I gave up on it quickly with my touring bike because it never seemed to do any good - I assumed that under such high pressure, even the smallest puncture pretty much rendered the tube useless. Also, even when using the tubes I'd bought with Slime already in them, it would occasionally back up into the stem so the valve didn't work properly and wouldn't close.

This morning, I had my first similar problem on the mountain bike. I tried to add a little air before riding in to work and Slime backed up into the stem and the valve then wouldn't close. It wouldn't deflate quickly, either, so I didn't have time to remove the valve & clean it out & put it back in - had to scrub the ride. I was SO disappointed - this is probably going to be one of the most beautiful days this fall.

I'm going to try taking out the valve and cleaning it tonight to see if I can get it to work again. LBS told me awhile back that what they do is shoot some air into the stem with their air pump before replacing the valve. I don't have a high-pressure air pump so I have to resort to wiping the stem out with a twisted paper towel tip, etc.

Any suggestions? Anyone compared the extra-thick tubes with standard tubes/Slime? I've never encountered this with a mountain bike tire before, and I've had that bike for five years. Did I maybe just get a bad tube?

Deb