Originally Posted by The_Aleman
I wouldn't trust that fix-a-flat stuff. Start with a new, unpatched (preferably thick) tube and Slime it yourself. I recommend also using a decent tire liner like Mr. Tuffy. I've had 3 or 4 tube-killing puncture flats in 20 years and I've gone at least 100,000 miles on bicycles in that time. Over 15,000 3 years in a row in the 90's!
You _can_ Slime a tube that already has punctures. I've done it several times. As long as they aren't serious, flat-in-3-minutes punctures, 6-8oz of Slime can prolly seal it. Any patches won't stay on the tube, and you won't be able to patch that tube ever again tho. Slime may also lose it's sealing if your tire is sitting in direct sunlight for a few hours. Then you have to pump it up and roll it for awhile to seal it back up.
Carrying the fix-a-flat stuff is more bulky and suspect than a new tube. Myself, I haven't carried a spare tube in over a decade.
I just go to walmart and buy foam tubes, no air=no flats, only issue is a little more road vibration