Update: Salmon cyclist killed in Rancho Mirage Saturday night

According to MyDesert.com, a cyclist was killed while riding against traffic in Rancho Mirage last night.

The rider, who has not been publicly identified, was headed east in the westbound on Highway 111 near Atrium Way when he was struck by a car traveling west at around 10:50 pm. KPSP-2 reports that he was pronounced dead at the scene.

No other details are available at this time.

……..

Some bike riders believe it is safer to ride against traffic, since it allows them to see oncoming vehicles. However, it’s actually significantly more dangerous because motorists aren’t looking anything approaching them on the same side of the road, and it shortens time both rider and driver have to react to a dangerous situation.

It also dramatically increases the severity of the impact by combining the speeds of both bike and car, rather than reducing the speed of impact as it would if both were traveling in the same direction.

For instance, if a car was traveling at 30 mph in the same direction as a bike at 15 mph, they would collide with a force equivalent to hitting a stationary object at 15 mph. However, traveling in opposite directions means the force of impact would be equivalent to 45 mph.

And that makes a big difference. It’s said that a pedestrian hit at 30 mph has an 80% chance of survival, while one hit at 40 mph has an 80% chance of dying.

This is the 6th bicycling fatality in Riverside County this year, and the 43rd confirmed cycling traffic death in Southern California since January 1st.

Update: The rider has been identified only as a 41-year old Hispanic male. While the cyclist appears to be clearly at fault for riding on the wrong side of the street, at least one local TV station seems to be going out of its way to blame the victim, as they quote a local resident questioning why anyone would ride a bike at night:

“I’m very sorry this man was killed but the average bicycle rider doesn’t ride at 11 O’clock at night,” Wells said.

Unless, of course, the average bike rider needs to get home from work or school, has someplace they want to go or just happens to enjoy riding after dark. You know, sort of like people in cars, but with fewer wheels.

And writer Jim Lyle questions my physics, saying that force of impact in a collision isn’t as simple as adding and subtracting relative speeds

It doesn’t work that way.  Ignoring differences in mass, if two cars collide head on at 30 mph, the force of the collision is not doubled; it’s the same as driving into a wall at 30 mph for each car.

For a bicycle/car collision, the differences in the masses are so large that the force of the collision is only marginally different if you are hit from behind or head on.

9 comments

  1. I’d like to see Jim Lyle’s references on that, or at least a better explanation. I know common sense can often be wrong, but right now I’m dubious about his assertions.

  2. youngpups says:

    Yeah, I’d definitely want to check Jim Lyle’s work. Think about the most extreme case. Cyclist riding 19 mph, car driving 20 mph. Can you still claim that direction doesn’t matter?

  3. Jim Lyle says:

    Youngpups is correct in the extreme case, direction matters a lot! Obviously, if you are bumped from behind by a car going approximately the same speed, the resulting force will be much less. However, when the speeds are significantly different, it matters little which direction you are traveling.

    Richard, momentum = mass x velocity and is conserved in a collision. You can do a quick search (google or bing – “collision physics”) and find articles that will take you through the math. I remember “Myth Busters” did a segment where they demonstrated the misconception.

    RSRO (ride safely, ride often),
    Jim

  4. @Jim: I understand the concept (the energy in the collision is the same regardless of impact direction), but I gotta ask: at what point does @youngpups’ X MPH difference in his thought experiment become inconsequential? That 3,000 lb car bumping me at 20 MPH has 60 kilojoules of kilojoules energy, whether I’m traveling 19 MPH in the same direction or hitting it head on.

    Now I’m thinking of my own Mythbusters experiment for this situation. What’s a good model? Maybe a bowling ball vs a ping pong ball?

    • bikinginla says:

      I’ve asked my brother for a little help on this one. Not only is he an Iditarod dog sled racer, he also has a Ph.D in particle physics.

      Although maybe I should have phrased the question in terms of a dog team versus a moose, rather than bike versus car.

  5. [...] no public identification for the cyclist killed in Rancho Mirage on Saturday night. The 41-year old Hispanic man was riding against  traffic when he was [...]

  6. Jim Lyle says:

    Major problems with any model of a car hitting a bicycle are the inelasticity of the real-world situation and what happens to the cyclist after the collision.

    The question is, how much of the momentum of the automobile is transferred to the cyclist at impact? My answer, “Never inconsequential.”

    Even a one mile per hour collision with a 5000 pound SUV is serious when you+bike only weigh 200+ pounds.

    Please stay safe out there.

    • bikinginla says:

      Good point. People think cyclists will just suffer a little bump or bounce off a vehicle in a slow speed collision. But any contact has the potential to knock a rider over or make him/her lose balance, potentially resulting in severe injuries — or worse.

      There is no such thing as a harmless collision.

  7. bikinginla says:

    Just received the following response from my particle physicist brother regarding how to calculate the force of impact between a bike and a car:

    Basically you are correct. Your reader is right that because of the mass difference between the car and the bicycle, it is almost the same for the bike as hitting a wall, but is would be at the vector sum of the two velocities, not the velocity the bike is traveling. Now if the car is doing 90 mph and the bike 10 mph, the small addition (or subtraction) of the bikes velocity to that of the car may not make a significant difference, but at that point I doubt the bike rider would care. If the car is also doing 10 mph, a rear end collision is just a tap, but a head on is like a bike at 20 hitting a wall.

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