If you love to ride tubulars, Tufo Tire Sealant is as close as it gets to an insurance policy. You can use it preventively by unthreading your tire valve and squeezing sealant directly into the tire. If/when you get a flat the sealant plugs the flat, often times with almost no pressure loss. Alternatively, you can use it after a flat, since the sealant can plug holes up to 2mm in diameter. One 70ml bottle is good for 2-3 tires. And note that this sealant comes with the bonus of one Tufo valve removal tool.