Big news for bike enthusiasts: Google announced that it will add biking directions in 150 cities to the popular Google Maps application. That means that in addition to calculating mileage and best routes for driving, walking, and public transportation, Google Maps users can select "Bicycling" as an option when planning trips.

Bicyclists can also use Google Maps features such as Street View and Local Search to preview bike lanes and find bike shops en route to their destination. The bike-trip planner is not yet available for cellphones or mobile devices, but Google officials say such an application is being planned.

You're probably thinking to yourself: but biking isn't anything like driving. How did Google find the bike paths, or factor in topography, or avoid biking traffic? Google's LatLong blog explains how engineers distinguished between generating bicycle routes as opposed to driving and walking directions. Google Maps worked with the Rails-to-Trails Conservancy to include 12,000 miles of biking trails in the system, and weighted the routing algorithm to prefer convenient trails to roads. Google also prioritized dedicated bike lanes in the 150 US cities. What's more, the algorithm recognizes uphill slopes -- understanding it might be more efficient to bike a few blocks out of the way than climb a particularly massive hill -- downhill slopes, busy roads, and busy intersections. The LatLong blog notes that cyclists' aversion to fast roads is "roughly the inverse of driving directions, where you want to stay on arterials and freeways," which necessitated an overhaul of many fundamental car driving calculations.

Other websites already provide biking directions, including ridethecity.com and mapmyride.com. However, Google being Google, the introduction of Google biking will attract a larger audience, or at least anyone who Googles the word "bike." Ideally, Google's heft could also influence city planners to create more bike lanes and more-reluctant bikers to put on a helmet and get peddling. And coupled with the greatest biking incentive in the world -- warmer springtime weather -- Google biking looks like it picked the right time to get into gear.