Barely one week after the training wheels came off his bike, 3-year-old Miles Peebles dominated the obstacle course Sunday at the fourth annual Sonoma County Bicycle Expo.

Miles pedaled hard in circle after circle around the chalk-marked parking lot on Fifth Street between Mendocino Avenue and B Street. He was still going an hour after his family rode the expo's two-mile family bike ride through town, said his proud father Matthew Peebles, 38, of Sebastopol.

"He just keeps going," Peebles said. "He already reminds me of a pro rider I know."

The annual bicycle extravaganza organized by the Sonoma County Bicycle Coalition drew about 4,000 people Sunday, a record number, said executive director Gary Helfrich.

In its first year located on a closed block of Fifth Street, Helfrich said he feels the event finally found its place after previous years at Santa Rosa City Hall and near the Second Street Post Office.

"A lot of people here were already downtown, saw the signs and wandered in," Helfrich said.

Vendors hawked all things bicycle in tents lining the downtown street, from piles of odd parts to high-tech cycling computers with GPS.

A main feature of Sunday's event was bicycle building. Welders bent over their work in the coalition's Velogenesis tent.

One tent over, Craig Calfee, founder of Calfee Design in La Selva Beach, near Santa Cruz, wrapped thick twine soaked in epoxy resin around the joints of what would become a bamboo bicycle frame.

Bruce Gordon of Petaluma's Bruce Gordon Cycles took a break from working to hold the stand as Calfee worked and talked shop.

Calfee said he built a bamboo bike in 1995 as a promotional gag, but "the bike rode so well, I developed it into a regular product."

Further down the street, children watched with open mouths as Stephen Hearn, 27, of Santa Rosa, spun around on the back wheel of his BMX bike and wrapped his leg around the bicycle in an elegant move called the Time Machine.

The demonstration was held by the local OneLove BMX collective, a promotional group that organizes events and BMX "jams" in the flatland style, meaning they do tricks without obstacles.

The group was founded by Hearn's roommates, Shayne Khajehnoori, 28, and Darin Wright, 38, who wanted to solidify a network of like-minded riders.

"Santa Rosa has a good BMX scene for a small city," said Khajehnoori, who said he likes to ride behind the Charles M. Schulz Museum and at parking lots near the Sonoma County Fairgrounds.

At a make-shift obstacle course in the parking lot behind Tex Wasabi's restaurant, Todd Barricklow, 43, of Santa Rosa, won the Cargo Bike Race competition.

He built a bicycle modeled after old timey bicycles he saw in Denmark that have a small front wheel and a compartment between the front handle bars.

He maneuvered the bicycle in figure eights around orange traffic cones and over a teeter-totter, hauling empty water jugs, barbells and other items. He nabbed the trophy against five other competitors with a one-second lead.

Barricklow, a ceramicist, said he can go just about anywhere in Santa Rosa on the hand-built bike.

"To be able to ride to Oliver's (grocery) with my kid in the middle and come home with groceries, a gallon of milk, even a six pack, was satisfying," Barricklow said.