I was down there last week (Sat-Wed)...with kids and no bike. In the city of Myrtle Beach, you couldn't even tell it was bike week. No crowds, and no more bikes than you would see at a regular time. We went to Barefoot Landing one afternoon and Broadway at the Beach one evening, and didn't see more than a couple of bikes at either place. I didn't go north, but I heard there were more bikes in North Myrtle Beach and some of the areas up there. Nothing like it's been in the past though.
Will