From TriMet TV:

When buses, trains and bikes share the road, it's even more important to practice safe driving and safe riding. Cyclists can help by following a few simple "rules of the road."

In downtown, it is especially important to be aware of buses and trains while biking, as many vehicles are sharing smaller spaces.  However, downtown traffic speeds are slow which allows bikes to share the road much more comfortably than on high-speed streets. 

*Did you know that the traffic lights downtown are timed for about 11 mph?  It's easy to keep up with traffic on your bike at that speed.  Plus, if you go that fast (slow?) you can catch green lights all the way across downtown!

Check out TriMet's nifty video on bike-bus-train love: