President Bush, always a bit star-crossed in his leisure pursuits, suffered a new misadventure in athleticism Saturday when he fell off a bicycle.

The president was in mile 16 of a 17-mile course on his ranch in Crawford, Tex., when he fell from a mountain bike, suffering scrapes and scratches on his chin, upper lip, nose, right hand and both knees. But, true to form, Bush stayed the course: After getting cleaned up by the White House doctor, he completed his bike ride.

Trent Duffy, a White House spokesman, immediately offered excuses for his boss. "It's been raining a lot, and the topsoil is loose," he said. In addition, Duffy reasoned, "He likes to go all out. Suffice it to say he wasn't whistling show tunes." Fortunately, Duffy reported, Bush was wearing a helmet and mouth guard.

The spokesman warned that Bush probably would be wearing a bandage on his chin when he arrived here Saturday night for a party for his daughter Jenna, who is graduating from the University of Texas this weekend.

For the president, there is something of a history of hapless encounters with sporting activities.

Years of running gave him two bum knees that have periodically left him limping his way to Air Force One. In December, doctors at Walter Reed Army Medical Center examined him with X-rays and magnetic resonance imaging and, finding some damage to both knees, recommended "cross training."

In other words, exercise such as mountain biking.

In January 2002, Bush was on the third floor of the White House residence, watching a football playoff game between the Baltimore Ravens and Miami Dolphins when he choked on a pretzel. This caused him to faint and fall, bruising and scraping his face. Bush was accompanied only by dogs Spot and Barney.

Then, in June 2003, Bush was visiting his parents at the family compound in Kennebunkport, Maine, when he fell from a motorized Segway scooter. Bush, who was holding a tennis racket that may have interfered with his coordination, did not hurt himself -- but the incident was captured by photographers and quickly beamed across the world.

Athletic miscues are a bipartisan affair, of course. Bush's Democratic challenger, John F. Kerry has fallen off a bicycle and taken a nasty spill while snowboarding. He blamed the Secret Service for the latter.

Bush's close calls predate his ascension to the presidency.

During the campaign in 1999, he scraped his right leg and hip when a truck trailer overturned near his jogging path in Austin. Bush dived for cover when chunks of concrete and wood were dumped behind him.

Around the same time, Bush went swimming in the pond on his ranch with his advertising strategist when the two men spotted cottonmouth water moccasins -- the only type of poisonous water snake in North America. That time, at least, Bush was not snakebit.

President Bush hurt his chin, upper lip, nose, right hand and both knees in a fall from his 17-mile route in Crawford, Tex.