Guys I've noticed that some of you talk about carrying a air pump on your bike and I've seen cyclist carry pumps on there bikes. My question is, if your carrying a pump you are obviously preparing for a flat, but if you get a flat your gonna need a tube because you obviously can't put air in a tube that has been punctured. So are y'all carrying a spare tube and a pump with you and if you get a flat you just fix it on the side of the road? I hope this isn't a stupid question, I'm still new to this commuting business and want to learn all this. My commute to work is only 4.8 miles, if I got a flat I could just walk the rest of the way if I had to. If you are changing these tubes on the side of the road, what kind of trouble are we talking about here? And what tools? Is there a tool kit you can buy just for that?