Too many sub-forums, unless you plan on the site expanding it's base. Right now it's road-focused people, so stuff like swimming, mountain biking, etc is something the roadies do, but not that often. Can always post about those topics in the big forums.
Makes 6. Good enough for now. Seems like all the swim/bike/run/mountainbike/cyclocross/track forums will go a bit underused. If you ask me, that's a big problem on BF...lots of sub-forums that just never get touched.