Sen. Scott Brown’s most famous mode of transportation might soon be something other than his celebrated pickup truck.

The Massachusetts Republican recently has been spotted more often on two wheels than four. A tipster says he saw Brown on Monday exiting the Dirksen Senate Office Building wearing full-on cycling gear and pushing a bike — quite a change from the beat-up old GMC truck that he made famous during his Senate campaign.

When a Capitol Police officer remarked on it, Brown told him about his hobby.

“It’s more expensive than my truck,” he told the cop. “It’s the one thing my wife lets me do.”

A Brown spokesman says the Senator is gearing up for this summer’s Pan-Massachusetts Challenge, a two-day bike race that raises money for cancer research.