It's my experience. In case of unidentified punctures the foam leaks out (of them), and then you can remove the splinter, or whatever by hand, maybe with a paper tissue, or tweezers from your swiss officers knife, some multitool. Dunno. I don't have that many flats. About 5 or 6 since 2005? Each one maybe a 10 to 15 minute break.
edit: Thinking about it, one could even omit the spray can because in cities there's almost always a gas station near, which is stocking that stuff. So only the small adapter would be necessary, if your valves aren't like the ones for cars anyways. I didn't do that so far because I'm often bicycling out of the city, instead of into it.
edit: Thinking about it, one could even omit the spray can because in cities there's almost always a gas station near, which is stocking that stuff. So only the small adapter would be necessary, if your valves aren't like the ones for cars anyways. I didn't do that so far because I'm often bicycling out of the city, instead of into it.