The jockey weighs 65 kg, his two-wheeled steed exactly twice that, and they cover ground at more than 300 km/h. The power of more than 200 horses is locked within Michael Doohan's 500-cc racing motorbike--so much energy that while the circuit timer might clock him nearing 320 km/h, the telemetry from the bike, which feeds into a computer in the Honda pits, shows a speed of 345 km/h. The discrepancy comes from wheel spin: the acceleration is so ferocious that the bike literally flies, its back wheel unable to put all that power down on the track.

Yet the quiet, blue-eyed Australian is keeping enough contact with the earth to be heading for consecutive world champion ships. With three Grand Prix events remaining--Rio de Janeiro Sept. 17, Buenos Aires a week later and Barcelona next month --he will probably have to crash to be beaten by his only real threat, compatriot and fellow Monaco-dwelling tax exile Daryl Beattie.

1949.

When he won the world championship last year, Mick Doohan, 30, was either first (nine races), second (three) or third (two). Not since Italian Giacomo Agostini, way back in 1968, has a rider had a place on the podium after every race. With 317 Grand Prix points for the 14 races last year, Doohan also became the first rider to exceed 300 since the championship series began in

"At 300 km/h-plus, a motorbike wants to go straight ahead," says Doohan. "The front wheel is almost floating." But the emotional octane of the elite 500-cc engine-capacity races comes not from brute speed alone. Rather it is the combination of deep throttle and dire braking, the elan with which the jockeys push all those horses through the curves, heeling their bikes over in a way that suggests the reverse of Newton's law: Can something that goes down so far possibly come up again?

On the balcony of his comfortable seventh-floor apartment overlooking the Mediterranean, Doohan talks about his motorbike as though it possesses the quirks and personality of a thoroughbred: what it "wants to do," how it "feels," whether it "likes" a certain track. He is talking about the whims of not one but two Hondas, which his team of five mechanics strip down, rebuild and plug into computers after every hour of track time. The bikes cost more than $1 million each and are identical in every way. Doohan delays his choice of mount until the last minute because "for some reason, one always feels better than the other."

Simpler than this relationship between man, machine and speed-blurred bitumen is Doohan's attitude toward winning: "If you come second, you've lost." When he first negotiated a contract with Honda in 1989, there were the normal bonuses for first, second, third. "I told them I'm not interested in coming second or third," says Doohan, "so we'll make it a bigger one for winning. That's the way it is with all my sponsors."

The first-or-bust approach can be dangerous. Says retired 1993 world champion Kevin Schwantz, from his ranch in Texas: "Taking risks is a big part of winning championships, but you have to set them out against what you gain. Mick's fallen twice while leading this year and run off the track two other times. He's been lucky not to get hurt. He's not a guy who likes to win at the slowest possible speed."

Doohan says his style is aggressive but he always aims to "bring the bike home." He says crashes are part of riding a bike at the human and technological limits. Doohan does not believe he has more spills than most top riders, but frequently he has found himself sliding over the tarmac with friction chewing at his one-piece leather suit, and then the high-density-foam pads and spine guard under it. More than once the downed bike, bucking lethally alongside, has landed on him.

He has broken many bones and torn a lot of flesh since he started riding motorbikes at age nine on the Gold Coast of Queensland, but the crash at Holland's Assen circuit in 1992 was especially scary. "There had been a lot of crashes during that session, and there was some sort of fluid on the track," recalls Doohan, who hit the ground while going roughly 170 km/h. "The bike landed on me. I tried to twist out from it. I think everything twisted but my right leg." When he finally stopped, his right ankle was a mangled ruin. At one stage, the Dutch doctors were talking amputation.

"Today the ankle's basically fused," explains Doohan, "with no movement to it, or in my toes." He has a special boot that zips up the back so he can slot his rigid foot into it. That rigidity threatened his career: Doohan could no longer rotate his right ankle to work the rear brake pedal. The solution came to him in the 1993 Grand Prix at Jerez, Spain. His left wrist is also crash damaged; his fingers were steering and working the clutch lever, "But during the race," says Doohan, "I got to thinking that my thumb wasn't doing much." His suggestion was a piece of sushi for the Honda engineers: they made him a thumb-operated rear brake.

Since the Assen crash, Doohan has become the leading voice among the 500-cc riders for improving track safety, removing walls and opening more runoff space for spilled riders. If anything, the crash has tightened his ability to stay in a zone of total concentration on the track. The mental curtain begins to drop days before a race: even his 22-year-old Australian girlfriend Selina Sines and his stepfather Ken Johnstone, who drives Doohan's motor home to each European Grand Prix, get little small talk. "They say it's a battle to get a sentence out of me," admits Doohan, whose only sign of stress off the track is that he bites his nails ultrashort.

Though Formula One race-car drivers get more glory than their two-wheeled colleagues on the international circuit, the gap has been closing. The television audience for Grand Prix motorbike racing is 300 million people in some 100 countries. Fans are knowledge able and passionate, and crowds are increasing: total attendance this season is expected to be 1.35 million people, an average of 103,000 at each Grand Prix, compared with 88,000 last year.

Enthusiasm is highest in Europe and Asia. On a recent promotional visit to Thailand--which doesn't have a Grand Prix circuit--Doohan got a police escort, security guards and star treatment. "I was blown away," he says. "The status of motorbike racing there is amazing. I guess it's because two wheels are the main transport for most of the people."

Although five of the Top 10 500-cc riders over the past 45 years have been American, the sport has been slow to catch on in the U.S. "People say Hollywood gave motorbikes a bad name," says Doohan with a smile. "Some Americans straightaway think 'biker dude.'"

One question Doohan says he gets asked in America when he explains his job: "Can you make a living riding a motorbike?" Well, not such a bad one. In his Monaco garage, he has, along with a getabout motorbike for shopping, a current-model yellow Ferrari 355 and a Range Rover. He is thinking about getting a helicopter. His friend, neighbor and Suzuki-riding rival Beattie already has one. "I've got the books to read about flying them," says Doohan. "I just haven't had the time."

Right now, Doohan has some figuring to do on fat rival offers from Suzuki and Yamaha, although Honda is likely to dig deep to keep the champion. Doohan is also busy lobbying for a rule change he says will make 500-cc racing still more exciting: lowering the 130-kg minimum weight of the bike. Doohan has proposed a 5-kg reduction in 1996 and another 5 kg in 1997. "Top speeds would be much the same, but cornering would be a lot faster," says Doohan, who is "90% sure" the slimmed-down bikes will be racing next season.

Whether Doohan will be around to push for the second weight drop in '97 depends on whether his bike keeps "liking" enough Grand Prix circuits, whether his left thumb and enough other necessary parts of him remain intact, whether he keeps enjoying the "feel." When he loses it, he may enter the world of property investment. "Nothing too risky," he says, unaware of the irony.

DOOHAN O.K.

Until then, as Doohan hurtles toward his second world title, he is living up to the laconic logo on his helmet. It shows a cool-looking koala in dark glasses. Under it are two words: