Word is growing about free weekly skate jams at Surf & Skate's Sacramento headquarters. At least 20 skateboarders have been showing up each week since the Citrus Heights shop's custom-built Skatelite bowl and street course opened a year and a half ago. The skate sessions changed this week from Wednesday to Thursday nights. Most skaters are locals. But up to 60 people from as far as San Francisco and Truckee have dropped in to carve the bowl, practice tricks and learn from each other on any given evening, said Surf & Skate owner Bob Mitchell. "You'll see some of the best skateboarders in the country show up here," he said. "(These) nights are pretty off the hook." Mitchell was a record-