Question of the Day: Biking

Q: We all know that one should work or run in the opposite direction of street traffic.  But can you explain the rationale for riding a bicycle with the traffic instead of against it?  It feels wrong to me.

A:  A bicycle is a vehicle, and if all vehicles did not abide by the same rules, conflicts and confusion would occur too often, resulting in accidents.  To convince yourself, look at it this way: Would you ask the same question about riding a motorcycle?  Of course not.  Well, all of the underlying reasons for motorcycles to follow vehicle rules also apply to bicycles.  Still a holdout?  Studies do show that wrong-way cyclists are much more likely to get hit by cars.

Update:

Q: When you wrote about why bicyclists should ride with traffic (and not against it), you neglected to mention the main reason: decreased impact speed in an accident.  For example, if you're riding a bike at 15 mph and you're struck head-on by a car traveling at 35 mph, you're exposed to a 50mph (35 plus 15) impact.  But if you're struck from behind, you get a 20 mph (35 minus 15) impact.

A: Many readers wrote to express the same idea, but it's not quite correct.  First, the main reason that all types of vehicles (including bikes) travel in the same direction is not decreased impact speed in an accident.  It's the avoidance of accidents in the first place.  That's a basic rule for any kind of traffic.  Then there's this physics error: In a head-on collision the sum of the vehicles' speeds does not equal the force of the impact.  This is a common misconception, sometimes propagated by news reports.  Say two identical cars are traveling at 50mph and they collide head-on.  Each car sustains a 50 mph impact, not a 100 mph impact.  A cyclist will fare much worse than a motorist in nearly all collisions, of course, but the first one you describe, a head-on collision between a 15 mph bike and a 35 mph car, will not deliver a 50 mph impact to either party.

-Ask Marilyn