canklecat

That's a tricky one. I usually explore new-to-me routes with a group that's already familiar with the route. There's some safety in numbers and it's a good way to evaluate whether I think the route would be safe for me on solo rides.

Day of the week and time of day are huge factors. I often ride routes that some folks think are terrifying, but they're morning people and thinking of weekday daytime traffic. I often ride late at night and sometimes see maybe one or two vehicles in 20-40 miles.

Urban and suburban boulevards are often the absolute worst during the day, yet practically deserted at night. Boulevards -- those wide, 3-lane divided sorta-highways with medians -- subconsciously encourage drivers to go way too fast for conditions. Nobody pays attention to those 40 mph speed limits, so it's not unusual to see drivers going 70 mph, blasting through a suburb like it's an open freeway. But at night those same boulevards are empty, so I'll ride 'em after midnight. I'm a night owl anyway so it works for me.

My favorite routes are what used to be called "farm to market" roads in Texas, with the "FM" designation. But only FM routes that parallel major highways. The highways divert most traffic so there's much less competition for the old rural roads. But, again, it depends on the day and time. I avoid riding those old two lane highways when drivers approaching from my rear are facing into the rising or setting sun. I avoid them during rush hours (same thing -- low sun in their eyes). If the traffic is sparse, I'll reverse my route and ensure the sun is behind me.

Not all two lane highways are the same. Each has its own vibe, and drivers who use those roads have certain habits and expectations. There are rural highways where I'll take the lane because I know drivers will pass safely without drama. There are seemingly identical two lane roads where drivers are more aggressive, hostile or negligent. Takes awhile to get a feel for the vibe of a route and the personalities of the drivers.

Recently one of my usual routes that connects quiet access roads has been repaved. Right now it's the roughest chipseal I've ever encountered and very slow to ride on. And the road crews made the shoulder useless. They left an inch or more of loose gravel on the shoulder, and glued rumble strips along the painted line. The shoulder is now only 2' wide and no longer usable as a makeshift "bike lane." So I take the lane. Just riding the 400-800 yards along that route to get to my preferred destination is hair raising some days because the drivers are often hostile. But it's the only way to reach my destination. Riding the rightmost wheel track is just begging for a brush-by pass, extremely dangerous when being passed by trucks with extended mirrors, trailers, etc. So I'm assertive about taking the lane. They won't be delayed for long. Besides, it's also the route for the public school bus barn, so they'd better get used to slowing and driving cautiously anyway.

And I usually wear at least some hi-viz colors (my helmets have hi-viz yellow or white with orange highlights), since my jerseys vary from green and blue (which can blend in with roadside foliage or the sky and blue-gray asphalt roads). And I always run lights, day and night. Currently I'm using a Cygolite Hotshot 150 on the brightest and most annoying flash mode for daytime use. At night I'll use the slow pulse or steady mode. I'm not trying to blind drivers or annoy them, just get their attention. The Hotshot has a very narrow aperture of maximum intensity, directly behind me, so if the driver is giving me 3' or more buffer, they won't in the path of the most intense part of the beam. It's a good psychological nudge. For night group rides I use lower intensity steady lights, such as the tiny lightweight Cygolite Hotroad that straps around the seat stay or seat post.

gsa103

Narrow-shoulder, high traffic and high speed differential all make a road bad. I won't ride anything that has all three. Narrow shoulders and high traffic isn't that bad as long as you're going at the same speed as traffic.

As for the Varia, if it signals that there's a car behind, there's a 99.999% chance there's a car back there, no need to even bother looking. I don't think I've ever had a false positive, the closest things are when a car turns off behind you. And it tells you distance and indicates the closure rate, so you at least get an idea if it's going to be a high-speed pass. I wouldn't change lanes without looking back, but it avoids turning your head to check if a car might be coming.

The Varia works best in lower traffic areas, so that you can move over when a car is approaching. The main thing is that it can't differentiate between lanes, so if you ride primarily on 4 lane roads with moderate traffic, it will constantly be indicating cars.

billallbritten

Lordy that's pretty!

JohnJ80

Agree that it won’t produce false positives, but it will produce false negatives.

The sensor reports speed differential only so if a car is pacing you at the same speed, it will disappear and is a false negative. You must check visually before you turn into the path of the pacing vehicle.

Digger Goreman

Check the state Department of Transportation website. Georgia has numbers for iirc daily traffic on all high density roads and some subdivision roads. At least gives you some knowledge of where you should find less traveled routes.

reishi

This is a great thread full of excellent advice. I like reading everyone's experiences. I agree that the best line to take is constantly changing with the circumstances and the more you ride with traffic the more your skills, confidence and techniques will evolve.
For rural 55mph roads around my town here in georgia, I've found the sweet spot. It's definitely not the dead center of the lane - even when traffic is next to zero, this still irritates drivers to no end. A sure way to get honked and yelled at using this line unless I'm doing it for a specific reason to prevent passing or avoiding road debris etc.. 2 feet from the fogline is almost perfect, 3ft is almost too much , maybe 2.5' from fogline or shoulder is perfect for me.. leaves wiggle room on my right while discouraging brush by passing. If I get closer to 2 feet or less from the fogline I'll get brush by passes all day, and I don't feel visible enough to drivers when I'm that far to the shoulder.

I look at my mirror every 10 seconds during a ride to maintain awareness and also whenever I see oncoming traffic I'll glance in my mirror to see if a vehicle is approaching from behind, in which case I would get over from 2ft closer to 3/3.5ft from fogline to protect my lane. But just holding the 2.5' from fogline guideline has worked well for me for years with very few cars passing me into oncoming traffic.. and on the rare occasion it's not enough to deter an oncoming traffic pass, at least I'm not in the center of the road, closer to the shoulder gives more wiggle room in an emergency if I need to bail or the trailer they're hauling cuts over when they swerve back into my lane.

When oncoming traffic has gone by and it's clear the pass , sometimes I'll swing back over onto the fogline in an obvious manner to signal to the driver that my being in the lane was for a specific reason and I'll give a humble wave thanking them for waiting a couple extra seconds out of their day..

If I'm on a multi lane road around here they're usually 45mph I'll ride the LEFT tire track in the right hand lane, cars can pass fully in the left lane.
Those are some of the techniques that work for me.. fwiw.ymmv.

canklecat

Check out the videos for Jonathan Shubert's recent new 100 mile sub-3 hour record in England. He mostly rode a two lane divided highway. Statistically it's safer than the rural routes many of us prefer. But he had a follow car with a big yellow sign to help warn approaching drivers to either slow or pass safely. And Shubert averaged better than 30 mph so there was less speed differential than my 16 mph average on our rural highways where the marked 40-50 mph limit translates to 75 mph.

noimagination

It is hard to describe one's "line", because it is based on many variables, as most people in this thread have said. Factors that play into drawing the "line" (i.e. "I'm not going to ride on that road").
- Speed of traffic.
- Type of road, e.g. number of lanes, how wide the lanes are, whether it straight with good sightlines or windy/hilly, how many side roads feed into it, etc.
- Width of shoulder
- Traffic pattern (i.e. a road that goes from point A to point B, or goes past a mall or a shopping area with lots of parking lot entrances)
- Whether there is a parallel route, or a similar route close by, that makes a good alternative.

Where I (mostly) ride, there are only a few roads (other than limited access highways where it is not legal to ride bikes, of course) that I won't ride on. Here are a couple of examples:
#1 : 4 lane road, no divider, no shoulder, 40 mph speed limit but traffic routinely exceeds 50 mph with some people going faster (60 - 65 mph), good sightlines, lots of businesses opening onto road, few residences (the road that my workplace is on).
#2 : 4 lane road with a divider, wide shoulder, speed limit varies from 40 mph to 50 mph, traffic routinely travels at 60 mph with some people driving faster, again lots of businesses and one large mall open onto the road. A variety of parallel routes through residential neighborhoods are available.
#3 : 2 lane road, no shoulder, narrow lanes, a few driveways but largely a through route, shaded by large trees, 40 mph speed limit but drivers routinely drive 50 mph and sometimes more, also a bus and truck route - this is a beautiful road but there is another nice road that parallels this one with a 30 mph speed limit that is rarely exceeded and that many, many cyclists use.
#4 : part is 2 lane road, narrow lanes, parking on both sides, goes through a high-density shopping area. It then broadens to 4 wider lanes with no shoulder that passes a couple of malls and then narrows down to 2 lanes again to go through a residential area with few driveways (driveways for houses mostly access side roads that feed into this road). Traffic speed varies from 30 mph through the high-density area to 45+ when it transitions to the more residential area. There are parallel routes, but basically this road is just not attractive from a visual or cycling perspective, there's not much reason to use it unless you're going shopping or live on it. I would have no problem using it for shopping trips if I was car-free, but not for recreational cycling.

The first 2 I think are truly hazardous to a cyclist. The 3rd one is not quite as hazardous, but still scary at some times of the day (in the early morning going South - i.e. down hill - it is OK, when traffic picks up and going North - up hill - it is not a fun ride). The 4th is as described, OK but not pleasant and there are alternatives. There are so many roads to ride on in my area (unlike out West), that there is almost always an alternative to a road that makes you uncomfortable.

rsbob 

I live near two state two lane highways with posted 55 MPH limits which are regularly exceeded. They are used by commuters and lots of heavy trucks (dump, gravel, semis, large box trucks, cement mixers, etc). They have 3’ shoulders which sometimes have debris or have fallen a bit due to ground shifts. A cyclist gets killed every year on one of these.

20 years ago when there was far less traffic, I would ride these roads just about daily. Now I avoid them like the plague. There are secondary roads which are windy and hilly which eventually get me to the same places and are much more enjoyable but take 50% longer. Such is life (or possible death)