Many serious runners think the asphalt of a street is easier on the joints than the concrete of a sidewalk. When I was a runner, I didn't run long enough distances for it to make a difference. Running was painful on my joints either way!

Anyway, running can be safer than biking. A runner can legally run on the left side of the street and have a shot at jumping out of the way of an oncoming car. That's not an option while riding a bike. A biker can have a rear view mirror while biking on the right side of the street, but still the visibility would not be nearly as good as a runner who's facing traffic. Also, a runner can still wear the reflective gear that lights up the runner like a Christmas tree.

Asphalt is definitely easier on your body compared to concrete, especially at temperatures 90 degrees or higher. At those temperatures, you can actually feel the asphalt soften and deform as you run.

Running might be safer than biking, and then again it might not, depending upon the individual. I routinely see lots of bikers traveling on the wrong side of the street; I think it is a great way to get killed.

Ok, so its some measurably small difference in the hardness of concrete vs. playing chicken with a 4000 lb. automobile? I'll stay on the sidewalk and buy a better set of running shoes.

One reason for running on the road instead of on the sidewalk is that the sidewalk tends to have more obstacles, overhanging trees, and uneven surfaces than the road. Running on the road is generally my preference over sidewalk in areas where I'm not too worried about becoming an impromptu speedbump!

Fortunately, where I live now has easy access to the city's Greenbelt, so I can avoid cars altogether.

Unsafe bike riders are a pet peeve of mine. I leave for work early in the morning, when it's still dark out. Every day I drive past at least the same three bike riders, who depend solely on those little reflectors on their peddals to help me see them. They have dark bikes and wear dark clothes with dark backpacks.

They are riding on the side of a busy road. No sidewalk. No bike lane. One or two lanes of traffic going each way, and surprisingly busy at that time of the morning. It seems inexcusably careless to me.

A device like the OP shows, or some of the others mentioned by other posters, would be a welcome addition in my mind. A light coloured jacket, backpack or a reflective vest would even be an improvement!

Bikes are not supposed to be on the sidewalk anyway.
I guess I should add that the sidewalk thing has become a pet peeve of mine. So many times I hear or read "why would they have the bike in the street when there is a sidewalk.

I am a cyclist,and I have been saving news paper articles about each bicycle related accident this summer.
In every case the cyclist broke a law.
Lights are required at night, travelling against traffic is illegal and riding at night with dark close is mentioned in the Utah bicycle guidelines, my son was hit one night wearing black, He quickly found out he had no leg to stand on in court.
And yes the side walk is illegal in many areas. It is also unsafe.

Here in NJ bicycles are required to have a horn or bell of some sort if they ride on public roads.

If they ride on public roads at night, they are also required to have a white headlight and a red taillight, both visible for at least 500 ft.

Finally, bicycles are given the same rights and duties as cars. Therefore, they are supposed to ride the same direction as traffic, they aren't supposed to ride on the sidewalk, and they have to obey all standard signs and signals (and I've seen cops give tickets to bicyclists for running stop signs).

The one major difference though, is that they are supposed to ride as far right as possible to allow faster vehicles to pass. However, they are allowed to cautiously enter the middle of the lane when necessary (like when turning left, avoiding road debris, avoiding cars doors, ect).

All in all, I've found that when drivers and bicyclists are aware of these laws and follow them, they tend to have few incidents. It's when someone fails to obey them that we get big problems (usually ending up in a hurt bicycle rider, regardless of who was in the wrong).

With that in mind, when I take my bike out, I do it with the understanding that it's a fairly dangerous activity and I need to be as cautious as humanly possible. Under the same token, when I see a bicycle on the road, I do my best to be cautious of them, stay as far away from them as possible, and let them do what they're going to do.

Even if I'm the one in the right legally, I would hate to injure someone else, especially when it's in a completely avoidable situation.

If a biker has never driven a car (e.g., biker is only 14 years old), then the biker does not fully understand the perspective of a driver. When I was 14, I biked everywhere I could. I thought drivers were naturally looking out for bikers. I didn't realize until I started driving, that's not the case at all!

Likewise, if a driver has never driven a motorcycle, then the driver is unlikely to be looking for motorcyclists. That brings up another point. Motorcyclists think a really loud motorcycle is a safety feature. Are you kidding me? Most times, I don't hear a loud motorcycle until it is beside me. An accident would have occurred before that. I'm sure the motorcycle is loud to the rider and pedestrians, but not to drivers, especially not on the freeway.

I consider myself a good driver. (I have never been in an accident in my 23 years of driving in all types of conditions.) However, while driving, I am NOT actively looking for bicyclists or motorcyclists. They are simply another part of the road activities of which I am generally aware. They aren't a priority of my awareness like the car in front of me is.