I have Michelin on the Peugeot and my LBS put something in there called AirLoc or AirTight??....anyway - since we have horrific thorns out here all our bikes need thorn resistant tubes and Slime or this new stuff....it doesn't add any weight to the bike but if the tube Is punctured, it seals the puncture. I'm hoping I don't have to find out first hand how it works but I have a CO2 cartridge just in case!