Originally Posted by CommuteCommando

I once got on the train with a tire that had gone flat over night with plans to fix it on the train. A newby with a big box bike got on and was all over himself with amazement that I was fixing a flat right there on the train. We talked bikes for the next forty minutes or so, with me explaining how to fix a flat, and the importance of knowing how. Somewhere in there I remember suggesting he pack a 15mm.