WASHINGTON'S BIKE TRAILS are urban delights, tranquil tree-lined paths through the sturm und drang of city traffic. At least on weekdays.

On weekends, because they are so inviting, they are often jammed handlebar to handlebar. Which is why experienced cyclists are usually off spinning their wheels on quiet country roads outside Washington.

Rural Virginia and Maryland have been popular with bicyclists since the 1890s, when phalanxes of cyclists, in the latest knickers and bloomers, rolled over the hills every weekend.

That was when the first roads were paved for bicyclists, bike clubs made the nation's first good road maps and presidents and members of Congress attended bicycle parades down Pennsylvania Avenue.

Riding on open back-country roads is a liberating experience. Not only are the scenery and hills breathtaking, but you feel slightly drunk on fresh air. The constant breeze carries the smells of woods and farms. It can be a musical, almost mystical experience, especially on roads with little traffic -- until a bug hits you in the eye or you have a flat tire.

Thanks to local bike clubs and a cycling couple from Takoma Park, there are now excellent map books to lead you through the maze of suburban streets and out onto hundreds of low-traffic rural roads that surprisingly still exist near Washington.

You can chart your own course with the two new Cycleways books of Gail and Charles Helfer, who have pedaled and driven more than 8,000 miles to map almost a hundred nearby bike rides.

And in a few weeks, bike shops will have the expanded new third edition of the Greater Washington Bicycle Atlas (a cooperative effort of the Washington Area Bicyclist Association and American Youth Hostels Potomac Area Council). It will have 68 of what many consider the classic country rides near Washington, plus more than 200 pages with almost everything you need to know about cycling in the mid-Atlantic states,

If you like company or are new to road riding, you can join one of the bicycle clubs that lead several dozen rides here every weekend. You can choose rides over flat or hilly terrain, at every pace from leisurely to blistering and at distances that range from 10 miles to 100. The century rides usually provide fruit and juice stands at 25-mile intervals and sag wagons for those who fall by the wayside.

With more than 3,000 members and sometimes 25 rides on a weekend, the Potomac Pedalers Touring Club is one of the nation's largest and busiest recreational cycling clubs. It provides leaders and maps for all rides and welcomes nonmembers. Day rides are usually free and are listed in the club's excellent monthly Pedal Patter. Most bike shops have a copy you can look at. This weekend, for instance, the club has scheduled fast hilly rides to the Blue Ridge Mountains from Fairfax and Montgomery Counties; and many moderately paced rides, such as 63 miles from Greenbelt to Columbia, 53 miles around Middleburg horse country, 40 miles from Vienna to Arcola, 25 miles around Darnestown and 15 miles on the W&OD trail west of Vienna. Many include lunch stops at inns or pizza (carbohydrate-loading) parlors.

Other smaller clubs and the Potomac Area Council of the American Youth Hostels also schedule day rides and some overnight rides to places like Harpers Ferry, the Easten Shore and the Pennsylvania-Dutch country where the movie "Witness" was filmed. The AYH council here also sponsors what has become Washington's single biggest bicycle outing, its "Moonlight Madness" night ride around the monuments and memorials. Last fall it attracted about 3,000 cyclists.

Many clubs and several new bike-touring organizations here now also sponsor weekend and one- from the Eastern Shore to Canada, Europe, the Middle East and even China. These also are geared to both experienced and inexperienced cyclists, and many are suitable for entire families.