If you go

What: Holiday mountain-bike clinics for kids

When: 9 a.m. to 12:30 p.m., 12:30 to 4 p.m., or all day; Dec. 21-23, 28-30

Where: Boulder Indoor Cycling, 3550 Frontier Ave., Suite A

Cost: $40 half-day, $70 full-day

More info: boulderindoorcycling.com or 303-292-5464

Six-year-old George Williams can throw down some totally sick tricks on his tiny Gary Fisher bike. And he just got his training wheels off this spring.

That's because when kids go to mountain bike clinics over school breaks at Boulder Indoor Cycling -- like George and his twin sister Mia have since this summer -- they leave knowing how to ride down steps and roll over a rock, even if it's on a pedal-less Strider scoot-bike.

"He can pop a wheelie, and he can stand on the frame while it's rolling," said George and Mia's mom, Elizabeth Williams. "He's passionate about it -- it's just his favorite thing."

Boulder Indoor Cycling's half- and full-day holiday clinics for kids start next week, but they're already booked both Monday and Tuesday, says BIC owner Rodrigo Garcia.

Garcia, a parent of two (but soon three), said that Boulder Indoor Cycling has been offering clinics for kids on days when school isn't in session since the velodrome opened earlier this year; there's also an after-school mountain-bike program. As a busy, working parent, he liked the idea of having a cycling day camp for the kids during school breaks.

"Your kid is happy and tired, he did something healthy, and I had my day of work," Garcia said.

In the holiday camps, for children ages 5 to 10, kids learn skills indoors on the ramps, logs and see-saw obstacles that fill the inside of the velodrome's track. The obstacles -- built by Garcia and his father -- are arranged in routes, called pump tracks, that are rated green through double black for difficulty, like ski runs.

"This is a technical mountain bike course," Garcia said. "It's not about speed."

Aside from learning balance, turning and standing on the bike pedals, coaches also teach safety and even bike mechanics.

"By the end of the day, they'll be able to go home and tell mom and dad that they learned how to ride a green track mountain bike course, and they've learned to fix a broken chain if their chain falls off," said Anna Polovin, director of CycleTykes, the children's classes at BIC.

The kids even get some single track in on a little trail behind the velodrome and learn how to ride over a curb, Polovin said.

The holiday camps are limited to 15 children. Polovin said there will probably be four coaches per 15 kids, and that most of the coaches are University of Colorado students who are enthusiastic about both cycling and teaching children.

Though the holiday classes are for older children, Polovin teaches kids as young as 18 months. She said she's constantly amazed by how quickly kids move from pushing the Strider bike to pedaling and beyond.

"We have a 5-year-old who has passed our toughest routes, which is double-black diamond."

But it's not all riding. The kids take snack breaks, draw and create their own tracks, too, said Williams, the mother of twins.

"It's really low key," she said. "There's a routine and there are rules, but it seems like everyone's just happy."