I like to put helium in my tires.
seriously, you'd be suprised the stuff on your bike you don't need. Think about the seat. Why's that thing so comfy anyway? You don't sit on it that much comparatively. I'm rockin the wantanabe but for style points i drilled it in rows. Be careful though. A bike should be well balanced for the rider. Sometimes Its better to have more weight on a certain end.