Why do many people carry 2 or more levers? I am always able to slip tires on/off with a single tire lever. I always carry an extra tube, small patch kit, a single tire lever and a micro pump. I have CO2, but to me it is a complete waste (unless racing or in a club ride) when you can pump up your tire for free.

Levers:
http://www.pedros.com/levers.htm
Pump:
http://www.topeak.com/products/Mini-Pumps/MicroRocketAL
Patch kit:
http://www.parktool.com/products/det...17&item=VP%2D1