Cycling is a popular summer sport at Lake Tahoe.  There are great opportunities for road bike riders as well as mountain bike riders.  There are several local places to rent bikes, if that is convenient.  Lake Tahoe also hosts several demanding rides for competitive atheletes.

Note: there is bus service (Tahoe Area Rapid Transit aka TART) along the major routes in case you want to ride one way and return on the bus.

Road Bike Routes (see maps below)

also ...

Mountain Bike Rides
Alpine Meadows to Pacific Crest Trail
Alpine Meadows Road

Bike Rental
Factory Bike, Rt 89 at Squaw Valley Rd.
Cycle Paths Mountain Adventures, Truckee
Olympic Bike Shop, Tahoe City