I have a well-supplied saddle bag with two spare tubes and CO2 cartridges. The only problem is that I'm too cheap to get more than one and I don't always remember to switch it from bike to bike. So far I'm batting about .500 on having it with me when I flat. The last time I called one of my riding partners who I knew had the day off. He came and got me and didn't say a word. If it hadn't been his day off I'm not sure if I'd have called my wife or walked the five miles or so to my house.
By the way, Biker395, how do you like the ride of the Colnago?