The number of Americans who commute via bicycle jumped by 64 percent between 1990 and 2009, yet the laws that protect them have lagged behind. Nationwide, the bike safety landscape looks like a patchwork of state regulations and variations in enforcement. In most states, the only law explicitly addressing bike safety is a safe passing law requiring drivers to give cyclists a cushion of anywhere from two to four feet. In only three states is it a felony offense to maim or fatally injure a biker or pedestrian if you are behind the wheel of a car. And in nearly every state, getting police or the courts to prosecute a negligent driver for harming a cyclist is a serious challenge. Some 726 cyclists were killed by cars last year. Reporter Andrew Zaleski sets out to see what can be done to lower that number.