A bus rodeo, sad to say, is not a spectator sport. There are no spurs, the riders wrestle steering wheels, not steers, and the horns on a bus can't draw blood, the last we heard.

But Metro's fifth annual Bus Roadeo (as the organizers insist on spelling it) still came off yesterday with the same display of deft maneuvers and style under pressure.

The action, if that is the word, took place on a large concrete parking lot at Metro's newly completed bus garage next to White Flint Mall in Montgomery County. Twenty drivers, judged by their safety records and semifinal eliminations to be the cream of Metro's crop of 2,600 bus operators, wheeled Metro buses at a speed of 2 mph through a tight maze of phosphorescent orange pylons.

Tension ran high for the drivers who had to negotiate the course in seven minutes without hitting a pylon. At stake was a trip to Boston in October to compete in the national Bus Roadeo.

"You're competing against everybody," said Frank Spadaro, a Metro instructor who won the local title, went on to take the nationals in 1978 and now ranks as a full-fledged celebrity in Metro circles. "You come off, you're sweating. When I got off the bus, I was so tensed up I couldn't say anything. I had to sit down for five minutes."

On his run, Vasco Cambridge, 38, wiped his palms and edged his bus out of the starting gate, through a gate called the Serpentine. He had to maneuver a bus 40 feet long, 8 feet wide through turns that afforded a margin in some places of only 3 inches. His wife Lorine watched his face from afar with binoculars.

Cambridge jogged right, guided the double back wheels through a row of rubber balls and essayed a right turn, one of the most difficult maneuvers in bus driving. He winced as a pylon fell. Next he made a stop, backed the bus up, performed a left turn, another reverse, and then stepped on the gas, needing a burst of speed to run through a narrowing gauntlet of pylons at 20 mph before slamming on the brakes. He was supposed to stop 6 inches from a final pylon.

The bus was a foot from the pylon and he was penalized 50 points, killing his chance for first place in all likelihood.

At every turn a driver's performance was monitored by police from jurisdictions all over the metropolitan area, who took points off if a driver so much as nicked a pylon. A perfect score was 650, which has never been attained in the history of the rodeo.

The route on the streets of Washington that the course most closely resembles is G-2, which runs through the narrow streets of Georgetown where a lot of cars double park, said Metro safety instructor Napoleon Jones.

For spectators, most of the course offered as much drama as could be had watching a traffic jam, although Metro employe Delores Simmons insisted the competition was interesting. "You see them drive so well out here," she said, "and then in the city they kill you."

Actually, a commuter should be so lucky to have one of these 20 drivers at the wheel of his bus. "Nothing but skill out here," said Chuck Schoenfeldt, a Metro safety instructor. "There's 20 guys with a total of 106 years without an accident. The rodeo tests their skills, but its purpose is basically for safety."

Luckily the rodeo coincided with the annual Metro picnic. While the buses inched through their paces, a crowd of several hundred Metro employes attended to fried chicken, Myklar the Magician and the springy pleasures of an enclosed plastic bubble called Moonwalk that was full of small children flipping and jumping about.

"That looks like a normal business day for me," joked Metro General Manager Richard Page.

Two hours later, the saddle-sore bus drivers had completed their rounds. And the winner is . . . Sorry, Metro waits until its annual banquet in October to crown the king of the competition.