Originally Posted by Maxwell

notubes.com

or search for "ghetto tubeless" threads on MTBR

There are bicycle specific fix-a-flat cans, hutchinson makes one.

They work on small punctures. Sealant can work better in tire without a tube. A tubeless tire doesn't pop like a thin tube. If you get a big enough hole though, you have to either use a tube and boot or patch the tire (not feasible on the roadside).

Tubeless can be a bit fiddly if you aren't using tubeless or tubeless-ready tires. But the fiddling is in the garage rather than on the road or trail.

I have big apples tubeless, I've had only one flat in probably 10k miles. Happened after parking the bike. Pumped back up and sloshed the sealant, sealed right up.