Going to ask a naive (I guess) question. I can see carrying a patch kit to get you home, or a spare tube to replace the one holed. But I guess I don't understand why you would insert a new tube and take the old one home to repair it.. presumably to reuse it?? Why would you put your fate in a repaired tube? They are not that expensive, particularly in light of the investment in your ride (bike and perhaps distance from home), unless you get lots of flats. Help educate me.