Black cats and other chimermas aside, I think the soluyion here is simple. Forget what I and every other arm chair quarterback has posted (badshotomen excepted as he seems to have experience here). Here is the real deal. You and your biking buddies need three things:
1) A type A, hyper competative guy who has to be first. Let him lead the the way.
2) A slightly out of shape "Hey guys, wait up" type to bring up the rear, at some distance.
3) a bit of "cat reppellant" (aka doe urine) liberally sprayed on his and alpha guy's packs.
The rest of you ride in formation in the middle and it should be no worries!
FQ13 who is a very, very bad person.