Check out the League of Michigan Bicyclists website. (
www.lmb.org)
Go to events, then go to Michigan Ride Calendar. It's not everything, but it's a reasonably good start.
There are also alot of clubs, but since I don't ride a road bike, I always feel out of place with the clubs. So maybe you'd have more luck with a club. (I have two bikes - a full mountain bike, and a hybrid with suspension... so that's my point of view.)
I do like to do some of the rail trails or other trails. Some of my favorite rides are around here (Oakland Country). There is a trail that runs along I275, and connects to Hines Park. Then branches off to UofM Dearborn. It's my 100 km (62 mile) weekend ride. And once they finish some construction, you can take the trail from Novi past Metro Airport. Not sure but it looks about 80 miles round trip.
Plus all the rails to trails in northern Oakland.
You can also use Google to map out bike trails.
Whew.... ok, enough for now. Does that help.