The "Winning Tour of America," a year-long series of bicycle rides across the U.S., winds up with one last roll Sunday in College Park at Wells Ice Skating Rink, 5000 Calvert Rd., starting with registration at 7:30 a.m. The 22-mile police-escorted circular tour spins through Beltsville Agricultural Center and includes races at Greenbelt Park. Top bikers Jonathan Boyer ('85 Race Across America champion) and Ken Carpenter (winner of the U.S./Soviet Michelob Challenge) are expected; your $10 gets you into the tour (helmets required) and a bike expo afterwards at Calvert Park; under 16 must be accompanied by an adult. Call HEY-BIKE.


The 20th Century Consort, courtesy of the Smithsonian Resident Associates and the Hirshhorn Museum, takes its cue from painting in the first concert of the season at 5:30 Saturday. Inspired by the Lucian Freud exhibit, the program "The British Discover America" will follow a 4:30 talk by the Hirshhorn's Edward P. Lawson. It's $12, $9 for seniors, $5 for students, at the Hirshhorn auditorium. 357-3030.


"Schubert, Schubert, Schubert '87," a three-concert festival at Georgetown University, commences Friday with performances by mezzo soprano Julia Bernheimer and pianist Robert Lehrbaumer. Harvard University's New World Quartet performs Saturday and the grand finale features the Trout Quintet Sunday. Bring a friend who's never been to a classical concert and he or she will be admitted free. Tickets are $5, $3 for seniors and students; $10 for all three concerts. Kids under 14 are free. It's at Gaston Hall, 37th & O NW. 699-5440.


Tour Annapolis with the sixth annual Historic Hike Saturday or Sunday and see how much things have changed since the 18th century. Hikers can gather at 11 or 1:30 both days at the Victualling Warehouse Maritime Museum, 77 Main Street; the two-hour walk will end with refreshments at the Shiplap House on Pinkney Street. It's $5; $3 for students and seniors, free for kids under 6. 301/267-8149.


Tune into the National Symphony Orchestra's annual 10K at 8 Sunday in West Potomac Park, where you'll be able to race with NSO musicians, including violinist Desimont Alston and trumpeter Adel Sanchez, and others. Prizes will be awarded by radio personality Dennis Owens. It's $10 to register Saturday at the Kennedy Center's FANS office, $12 Sunday before the race. 254-8700.


Roll over to the Rallye on the Potomac (it used to be called the Great Washington Bed Race) from noon to 5 Saturday at Oronoco Bay (between Pendleton and Madison streets) in Old Town Alexandria. More than 20 teams will fluff and puff to raise money for the Muscular Dystrophy Association. Watching is free. 823-1115.


The National Gallery of Art Vocal Arts Ensemble performs a free concert in the West Building, Sixth and Constitution NW, at 7 Sunday. 737-4215 . . . stock up for winter at the Smithsonian's Bird Seed Sale at the Smithsonian Environmental Center, Contees Wharf Road in Edgewater, Maryland. 261-4190 . . . Pleiades, a group of seven area women jewelers, presents its second annual exhibit and sale of unique earrings, necklaces and more 11 to 5 Saturday and Sunday at Garrett Park Town Hall, 10814 Kenilworth Ave. in Garrett Park. Free. 622-3187.


If the mere mention of a '61 Silver Cloud Mercedes makes your heart skip a beat, you may want to check out the Baltimore Washington Auto Swap Meet, Auction and Show 10 to 4 Saturday and Sunday where you can buy, sell or swap parts or just admire antique and classic cars and parts. It's at the Prince George's Equestrian Center in Upper Marlboro. Admission is $2, under 12 free. 596-0754.


It's pre-Halloween family fun at Potomac Day 9 to 5 Saturday in Potomac Village. It starts with a fun run and includes a parade at 11:30 down Falls and River roads, craft shows, a costume contest, pony rides, balloon rides and free refreshments. Dress up Spot and register him by 12:30 for a Halloween costume contest for pets (which also includes a Frisbee canine contest). Free. 299-2170.

Speaking of pets, Pet Farm Park is usually the place to meet exotic and domestic animals but between 10 and 5 Saturday and Sunday visitors can help stuff the world's largest scarecrow. Loretta Long -- Susan of "Sesame Street" -- will be there 2 to 5 Sunday to check out the giant that may reach five stories in height. It's $4, $3.50 for kids 12 to 2 at 1228 Hunter Mill Rd., Vienna. Part of the proceeds will go to UNICEF. 759-3636.


There's a baseball card show at Armory Place, 925 Wayne Ave. in Silver Spring 10 to 5 Saturday and Sunday with dealers from across the country selling cards and baseball memorabilia as old as 100 years. 585-5564.

Step up to the political memorabilia show 10 to 4 Saturday at the Westgate Motor Hotel, 6401 Baltimore National Pike in Baltimore, where you can buy, sell and trade campaign buttons, posters and other political paraphernalia. Admission's free. Call 301/744-6572 for more information.


Saturday being the 129th aniversary of Theodore Roosevelt's birth, the National Park Service is holding a "Potomac Shore Clean-Up": Between 8 and 12:30, NPS asks volunteers to gather on Roosevelt Island to pick up litter at several locations along the Potomac. Good things come to those who help: There's a birthday party afterwards till 5 with the Rosebud Ragtime Ensemble, Post Nuclear Jazz Band and U.S. Army Fife and Drum Corps and others. For information: 285-2598.