So far I pretty much stick to bike paths, roads of any speed with shoulders (usually 3'+ wide), and occasionally shoulder-less roads with speeds 35 mph or less (maybe even 45 mph). The other day on a 65 mph road with wide shoulders, the wind from passing semis sometimes made me swerve a bit.

ok

A big factor for me is how much traffic there is in the first place. We have a lot of rural FM roads around here that are shoulderless with 65 mph traffic, but with a car about once every 5 minutes, and they're pretty decent places to ride (and very few semis, too.)

Yeah, traffic would definitely be a factor in considering a route. There are a lot of great roads here in Colorado, but they have no shoulders and lots of high-speed traffic. I just read in a road bike book that the author considers highway 85 between Denver and Castle Rock suicide. Just wondering where people draw the line I guess...

There is a road here with 3 ft shoulders that is a 45 mph zone. The lanes are pretty narrow and even though there is a 3 ft strip I avoid when I can because of semis and dump trucks.

Life would be nice to simply jump on the road without doing risk analysis to see which route one should take...

I am real careful where I ride. Today I was on a busy road with parked cars on shoulder and where wasn't three feet between the parked cars and the traffic. So, I needed to get up on the side walk or I may have become a road pizza.

That's what's nice about where I am. 4 hour rides with 1 or 2 traffic lights and about 10 cars.
I avoid the busy roads as much as possible.

Um.... stay off 65mph roads?

use the farm roads.

One of the benefits of racing cyclocross is having a cross bike for exactly this purpose. Depending on the quality of your farm roads, gravel grinding can be a great diversion and opens up a whole other world of route possibilities! Plus, you only have to avoid the occasional piece of farm equipment or wildlife.

you're riding with semis going 65? seriously?

Yeah...I did a loop one day not realizing there was about a 10 mile stretch of 60mph road with about 6" of pavement to the right of the white line. It was the most terrifying 10 miles I had ridden in a long time. It was about 3/4 of the way through my ride, so I didn't have the option of turning around and going back the way I had come. Well...I did...but it would have turned a 50 mile ride into an 80 mile ride...which I would have had trouble finishing.

Suicide:

That's hardly unreasonable. I do agree with others about the traffic volume being critical. If you're frequently getting passed by big trucks then I don't blame you at all (and wouldn't ride that road either).

Heh, guess I'm glad nobody said "HTFU!" Colorado's DOT has a bicycling map and many roads are highlighted for bicycling but say they "have shoulders less than 3-4 feet." I checked out some of these roads and they often have NO shoulder, plus speed limits of 55-65 mph. And I say, srsly? There are also a lot of long, windy, shoulderless canyon roads around here, with speeds up to 45-55 mph, and I see many bicyclists on those (like the high-traffic Morrison canyon west of Denver). I do bike 65 mph roads with (wide) shoulders, but no shoulders is just too nerve-wracking and risky IMO.

As opposed to sidewalk pizza when somebody pulls into or out of a drive? Take the lane.