"Because I'm ridiculously in love with my bike, I was willing to push through the pain at all costs," says Timmy Walsh.

In May, a car ran over Walsh's left leg, pulverizing his tibia and fibula as he tried to prevent the driver from leaving the scene of an accident — an accident in which the driver had knocked him off his bicycle only moments earlier.

"A foot to the left, she would've run over all of me — heart, lungs, who knows. I actually kinda lucked out," says Walsh. "But, getting money out of her is like getting blood out of a stone."

The driver carried as much car insurance as Walsh had health insurance: none.

After Walsh caught an ambulance ride from Third and Bainbridge streets to Jefferson hospital, surgeons from the Rothman Institute dismantled his knee, scooped out his chipped bones and replaced them with a metal rod. Walsh spent four days in the hospital with physical therapists. The bill, after being whittled down through negotiations, came to $50,000.

Walsh and some of his friends began hatching plans for a benefit bike race as soon as the morphine wore off. The race, a courier-style event dubbed "The Quest for the Holy Grail," will take place this Saturday, Sept. 30, at 2 p.m. in Washington Square (registration starts at 1 p.m.). The entrance fee is $5 per rider.

"I didn't call it an alley cat because I don't think most people know what it means. But I don't like to use the word race either because, technically, it's a scavenger hunt."

The event is indeed hard to classify. For one, check points on the courier-style course can be completed nonlinearly. Unlike other alley cats, the checkpoints require quick thinking, not the rote completion of simple tasks like dropping off and picking up packages. Points are awarded for accurately answering questions regarding medieval history, particularly the lore surrounding the multiple quests for the Holy Grail (hint, hint). Yes, a few points will be awarded for finishing first, donating money and wearing a costume, but not enough to tip the scales.

"There's no buying your way to the top, no favorites, no who's-faster-than-who. If you ride a nasty Huffy and you know medieval history, you have a better chance than some douche messenger with a fixed gear," says Walsh.

Although Walsh rides his bike daily from 47th and Kingsessing streets to the Dive for happy hour, he's not participating in the race himself. He is able to walk thanks to the metal rod, but his leg is still broken and won't completely heal for at least a few more months.

"I have to go back for a checkup every five weeks and basically the doctor grabs my leg and kind of squishes it like a cantaloupe to see if it's ripe," says Walsh, "and see how much my bones are moving — how rigid they are, how solid they are."

Instead, he'll be manning checkpoints, tallying scores and distributing prizes: gift certificates from The Wooden Shoe and Whole Foods, and something special from Mike's Bikes.

Walsh didn't want to approach bike shops for sponsorship, knowing that he wasn't the first or last uninsured cyclist to butt heads with a motorist, but Mike of Mike's Bikes heard Walsh's story and personally sought him out. He wrote him a personal check and packed a bag of prizes, no questions asked.

"I'm going to remember people who help me out," says Walsh. "I'm going to really appreciate whoever shows up."