Mostly on roads with a speed limit of 25mph or 35mph. On a road with any faster speed limit, the time it takes for an automobile driver to react to your presence is too much to travel safely. Add to that the fact that the cagers don't expect to see you and that speed limits in metro Detroit are a mere suggestion, all of this tends to keep me on the less traveled roads, even if it means weaveing a little out of my way.
Rather than spending money on bike paths, I would like to see the local cities around Detroit get together and lay out some bike "routes". These are routes that parallel major thouroughfares with traffic signals at major crossings, and have 25-35 mph speed limits. I have my own routes now but it would be nicer if they were marked and mapped. The cost would be much less than bike paths (signage and a few traffic lights). Some cities have these, but generally they don't go anywhere and they only for that particular small municipality. I think the existing routes are meant to keep children out of traffic, and not meant for commuters or transportation from point to point.
regards
Dan