You might have seen them on your way to work-old bikes spray-painted white, adorned with plaques, and permanently bolted to street signs. These Ghost Bikes are sobering epitaphs for bikers who've been hit or killed by automobiles. The first Ghost Bike appeared in St. Louis in 2003, and now the monuments have been erected by cyclist groups in nearly 30 cities around the world, serving as a stark reminder that drivers must share the road with more fragile means of conveyance. "I wish I never had to do another one," explains Ryan Nuckel, who helps create the bikes in New York. "But as long as there's a need, they'll continue."LEARN MOREghostbikes.orgDUBIOUS HONOR New York has 40 Ghost Bikes, the most in the world.