Massapequa resident Roy Walther will ride in the 25th annual Pan-Massachusetts Challenge (PMC), the nation's most successful bike-a-thon for charity, Aug. 7 and 8. Alone or in teams, athletes or amateurs, strong or weak, they ride to accomplish a single, unified goal - a world without cancer.

Nearly 4,000 cyclists from 40 states and six countries will ride in the PMC to raise $17 million, bringing the total contributed to Dana-Farber Cancer Institute through its Jimmy Fund to more than $120 million. The PMC's annual contribution funds lifesaving cancer research and care for cancer patients around the globe. More than 160 PMC participants are cancer survivors or current patients, while others ride in honor of a friend or family member fighting the disease.

"Unfortunately, everyone has a connection to cancer in some way," says Billy Starr, PMC founder and executive director. "The PMC gives people a way to channel thankfulness for effective treatment or grief over lost loved ones into positive energy that helps others."

Since its inception in 1980, the PMC has become the most efficient athletic fundraising event in the country, donating 93 cents of every dollar to the Jimmy Fund. Cyclists are required to raise between $1,750 and $2,750 to ride, depending on the chosen route. The average cyclist raises $4,300.

The PMC, presented by the Boston Red Sox, offers six different routes, traveling through 46 Massachusetts towns over one or two days, covering between 89 and 192 miles. Two-day rides include the original 192-mile Sturbridge-to-Provincetown route; 186-mile Sturbridge-Bourne-Wellesley route; 169-mile Wellesley-Bourne-Provincetown route. One-day riders choose between the 108-mile Sturbridge-Bourne route and the 89-mile Wellesley-Bourne route.

To become a volunteer, a virtual rider, or make a financial contribution to a rider from your town, visit www,pmc.org or call (800) WE-CYCLE. Checks can be made payable to PMC, 77 Fourth Ave., Needham, MA 02494.