I also try to avoid roads with on ramps, but there are a couple that are unavoidable. The one on the way to work isn't bad because i've got a traffic light that's always red when I get to it, but there's one ramp in Glendale on the way to a bike path I like to ride sometimes, I usually stick to the 'straight' lane and stay in the left tire track until i'm through the sketchy part, that way cars are less likely to pass me and cut me off.. like this.. (see image) It's always a little scary, but it's not really too bad because it's at the bottom of a huge hill so i'm usually going at least 35+mph at that point so I just cruise with the cars.