Post-race there is about as much activity as pre-race though with people posting pics and whatnot. Merging sounds like a lot of work for you anyway. I hardly ever looked at the rides/alleycats/races sticky because it's too much of a jumble.

I don't see anything wrong with each ride/race/'cat having its own thread. The ongoing rides will get bumped up to the top and the one-time events will drop down after everyone has posted the pics, etc...

If multiple posts on the same topic become a problem you could merge them by topic, or maybe just create stickies for the major races/rides.

Just my two cents for whatever it's worth.