* MULTIPLICITY: When tempted to run down the Washington area's flaws -- the bad traffic, the questionable air quality, even the aluminum can remnants of a beer six-pack seen floating on the Potomac River the other day, a line from a long-dead poet comes to mind. "But I love my poor earth," Osip Mandelstam wrote, "because it's the only one I've seen." This is it, for better or worse, so it is up to you to treasure the good stuff, which is abundant around here. You could start with a hard mountain bike ride on the curving singletrack at Germantown's Schaeffer Farms, scattering deer as you go, the thrill of weaving fast downhill nearly equal to that of tree skiing in Jackson Hole or Grand Targhee or any other place. An hour later you could be kayaking on the Potomac, fish darting and splashing out of your way, a sliver of moon lighting the passage home. Anyway, there is much to take part in, including the Wednesdays at Wakefield Mountain Bike Race Series, which continues this week at Wakefield Park in Annandale. Beginners to experts can test their skills on a roughly 3.2-mile loop with a handful of good climbs. The racing starts at 6 p.m. For more information, visit http://www.potomacvelo.com or write to info@potomacvelo.com. . . .

Tom Mathis will offer another of his mountain bike boot camps for beginners on July 11 at 8:45 a.m. at Wakefield Park. Spots in the free clinics go fast, so to reserve one (or to ask about the August and September clinics) contact Mathis at mathis.mt11@cox.net. For more information, visit

http://thebikelane.com/

site/page.cfm?PageID=91.

* DOUBLE UP: The Triathlantic Association will host the third annual Cedarfest Mountain Bike Duathlon on July 18 at 8 a.m. at Cedarville State Forest in Waldorf. The race includes a 10-mile bike ride and two 2.5-mile trail runs. And on July 25 the 12th annual Riverwatch Triathlon and Duathlon will be held in North East, Md., on Chesapeake Bay. The triathlon includes a .75-mile swim, a 16-mile bike ride and a three-mile run. The duathlon consists of two three-mile runs and a 16-mile ride. For details, directions and registration information, visit www.triath.com. To volunteer for one or both events, call 410-593-9662.

-- John Mullen

mullenj@washpost.com