Hard-core mountain bikers will understand why Oleta has won for the third straight year. It's by default. There isn't any real competition in Miami-Dade County. (Amelia Earhart Park has drawn too many complaints about reliability and availability to be a contender.) So that leaves Oleta, which isn't bad at all, given that South Florida mountain bikers must do without actual mountains. It's just that it's so crowded. And it's inconvenient if you happen to live down in Kendall or Pinecrest. (Many bikers are irked at the lack of any sanctioned tracks in South Miami-Dade. To get an eyeful check out Roger Sunderland's mountain-bike Website and click on Snapper Creek under the listing for Miami-Dade: http://members.aol.com/ cyclerog/page4.html.) On the plus side, Oleta is well organized and maintained, and it gives novices a chance to get the hang of the sport. Helmets required, a rule that is enforced.