A group of bicyclists yesterday tried to convince Metro officials to abandon a long-standing policy prohibiting bicycles on subway trains.

To prove that it can work, one biker carried a cardboard cut-out of a bicycle onto the subway elevator at the Smithsonian stop and then onto a train.

There was no apparent difficulty.

With Washington in the midst of a bicycling boom, the Citizens' Coalition for Bikers Metrorail is seeking the use of the rear car on each subway train -- and only on weekends.

"It's an idea whose time has come," said David Strom, president of the coalition. "There is no limit on the size of a package a person can carry on the subway, so why prohibit bicycles?"

Cody Pfanstiehl, Metro's public relations director, witnessed the experiment and even offered some friendly tips.

"Now, if I was your PR guy, I'd engineer conversion of the public to let the Metro board know that it's not just a bunch of bicyclists who want this thing," he said. "After all, we have 300,000 riders a day, and what the board is concerned about is the headline that reads: 'Bike Stuck in Door' or 'Old Lady Hit By Biker'."

Strom balked and called this a "scare tactic." He called statistics from a coalition study of 940 Metro trains that showed an average of eight people riding the last car of the Metro.

"You could also get hit by one of those guys pushing a Metro vacuum cleaner," Strom said.

Last year, a Metropolitan Washington Council of Governments study estimated that nearly half a million bicycle trips are made by Washingtonians daily. This area, coalition members said, has the largest congregation of bicyclists in the nation.

"We're talking about saving energy and improving the air quality," said Fred VanAntwerp, a U.S. Transportation Department urban planner and coalition member. "This is the going thing. Why is Metro so against that?"

In April, the Metro board rejected a proposal for bikes on Metrorail that called for issuance of permits, training sessions, clean bikes and access to subways only by elevator.

In San Francisco, a similar program has been in effect for five years, the coalition noted. So far, more than 4,000 bicycle permits have been issued and only four have been revoked.

"What you're up against," Pfanstiehl said, "is a conservative element on the Metro board that doesn't want to complicate an already complicated situation. Besides, we have a dozen stations where the elevators bypass the fare collection -- but we'll have to deal with that later."