The Washington region's first major paved bicycle trail was built 17 years ago in Rock Creek Park for good reason. It's one of the most scenic and peaceful places in the nation's capital.

It's also one of the coolest trails in summer, though sometimes as damp as a jungle rain forest, thanks to the canopy of century-old trees that covers this stream-valley park.

Rock Creek Park is an easy and generally safe place to cycle, at least on weekends when bikers don't have to share sections of Beach Drive with motorists. Starting Saturday, the National Park Service resumes its annual weekend-holiday ban of motorized traffic on most sections of Beach Drive between the Montgomery County border and Broad Branch Road above the National Zoo. The Rock Creek trail is narrow and winding, however, and has a couple of busy road crossings.

It is a 7.5-mile ride from the Lincoln Memorial to the Montgomery line, about half of it on Beach Drive and half on paved trails, with an optional ford of Rock Creek -- a slippery but fun crossing for two- wheeled vehicles.

There are lots of sights along the trail, including Pierce Mill and the Art Barn at Park Road, the Rock Creek Nature Center and Planetarium a mile away on Glover Drive, and the National Zoo beside the trail.

The zoo doesn't have all the animals. Deer, red and grey foxes, flying squirrels, white-footed mice and a feathery host of birds including barred owls and broad-winged eagles are inhabitants of Rock Creek -- although most are difficult to spot and only venture forth at night.

For a longer jaunt, you can follow Beach Drive and bike trails up into Montgomery County's Rock Creek Regional Park for another 15 miles as far as Rockville. And next year, the county trail will be extended an additional five miles to Lake Needwood near Gaithersburg.

Cyclists who don't want to retrace their paths can take the Metro subway back, at least if they have a Metro bike pass. The Rockville subway station is about one mile west of the current trail's end at Baltimore Road.