I'm surprised no one here has mentioned the obvious answer. I carry 1 spare tube, a patch kit, and 3 CO2 cartridges. That's all I have room for. On a long ride I can fix 3 flats (which implies I need a new tire). The patch kit is the last resort, but it's way smaller than a new tube, let alone an extra 2 tubes.

I do agree with others here, if I help some random stranger out with a flat I will patch their tube rather than give them my spare. The spare costs $6, a patch less than a $1.

I'm surprised no one here has mentioned the obvious answer. I carry 1 spare tube, a patch kit, and 3 CO2 cartridges. That's all I have room for. There simply isn't room in my saddle bag for two spare tubes. On a long ride I can fix 3 flats (which implies I need a new tire). The patch kit is the last resort, but it's way smaller than a new tube, let alone an extra 2 tubes.

I do agree with others here, if I help some random stranger out with a flat I will patch their tube rather than give them my spare. The spare costs $6-$7 plus the CO2, a patch costs $.50 plus CO2.