There are more and more brightly colored bikes parked on Valley sidewalks, just waiting for someone to rent them out.

Bike-sharing programs are expanding, and recently, a new model has emerged: dockless bike-sharing. That means there isn’t a specific place where riders pick up and drop off their bikes - they just leave the bikes where they’re going.

Valley cities have both dockless and more traditional station-based systems.

Casey Wichman is a fellow at Resources for the Future, which is an environmental economics think tank.