Tuesday, May 29, 2007

Bicycle Helmets

As I've often been told to wear my helmet more, I decided to do a little research, and thought I'd write a post on what I found. I browsed some websites and read some original research. Turns out though, I could have just read this amazing wikipedia article on the subject. It is chock full of information, referenced with many of the papers I read, and is completely reasonable in its conclusions.

The gist of it is that it's very difficult to tell if helmets do much or any good. From first principles, they should help if there is a low speed collision involving direct head injury. At high speeds a normal bike helmet will absorb very little of the total energy, and they offer no protection against rotational trauma.

Statistical studies, as is the norm with these things, are difficult and ambiguous. People who wear helmets seem to get head injuries less often, but they're different in many ways. Mandatory helmet laws have not been shown to have a statistically significant effect on the rate of head injuries.

Cycling is safer when more people do it - which is why cycling in the Netherlands, with little helmet use, is much safer than the US, with high use. Helmet laws that discourage cycling are therefore counterproductive.

Of course this doesn't necessarily answer whether I should wear a helmet (any more than the bozo who gets counted in condom failure statistics should impact my decision). My general rule - if I'm wearing sneakers, I'm wearing a hat. I'm traveling slowly, unlikely to fall over, and if I do I can react to prevent myself hitting my head. If I'm wearing bike shoes, I wear my helmet. I'm out for a real ride, up and down hills, and traveling at a higher speed. And given that I'm already going to go click-clack if I try to walk anywhere, it doesn't really matter that I'll have to carry a helmet too.

My final point is that regardless of whether you wear a helmet or not, cycling is not dangerous (by most people's definition). Conservatively, cycling is twice as safe as walking, per mile. Meanwhile, the benefits of cycling are obvious. I mean, obvious.


Alan Rosenwinkel said...

true story: Out on my bike ride this afternoon, I was riding very quickly down a steep hill, going well over the 30mph speed limit, when I catch up with the car in front of me and slow down, maybe to 25 or 30pm. I'm riding in the right half of the lane, but not all the way over, when a big SUV pulls out into the oncoming lane of traffic to pass me, coming relatively close to me on the way by. In literally 10 seconds the SUV, and the car I was following, get stuck in the usual traffic at bottom of the hill, so I pull over and stop next to the driver's window.

"Do you really think you're going to make up any time by passing me. I was even going over the speed limit" I said angrily. "you weren't riding in the bike lane" they answered. To which I made the obvious response "There is no bike lane! [by the tone of my voice I'm sure they inferred the 'you fucking idiot'] I have the right of way just like a car. You're putting my life at risk by trying to pass me like that." To which they responded "I don't ride a bike. I don't need to know the laws"

At that point, as you can imagine, I was absolutely infuriated. I started to ride off, yelling profanities as I left this person to wait in the traffic they passed me to reach. As I rode off, I hear her hell "watch your mouth white boy"

[angry and judgmental paragraph omitted]

Donnie said...

This is the kind of thing that made me stop riding a bicycle in traffic.

I was actually in a completely residential neighborhood, approaching an intersection with stop signs on the cross street. An SUV was approaching on the right. I assumed, stupidly, that the driver was going to respect the stop sign and let me go first. Instead, the driver didn't even look in my direction and I had to yell to keep her from hitting me. It was literally a matter of feet between me and the grille of the vehicle.

The worst part was, the driver acted like I was the one to blame. She completely ignored a stop sign and didn't even look one direction at the intersection.

I concluded that when you are on a bicycle sharing the road with motor vehicles, you have to assume they don't see you, and if they see you, they don't care. So I threw in the towel when it comes to navigating traffic-laden roads. With drivers like that, it seems like it's only a matter of time before you get hit by a car.

It was a bummer, but I'm just glad I didn't get mangled.

dave hiller said...

I'm not nearly so pessimistic about biking on roads with traffic. Sure, you have encounters like Alan described; I've had similar ones myself and they piss me off to no end. I'd bet you've also had similar ones in your car too though. Perhaps you don't feel as close to an accident/injury in that case, but that's not much backed up by statistics. Read the article I linked to in my original post: cycling fatalities in the US are estimated to be 72 per billion kilometers travelled. BILLION. Depending on your source, cycling is safer than driving or up to 10-20 times more dangerous. Meanwhile, cycling is good for the environment, and it's good for your long term health. By getting off your bike and into your car, you might decrease your chances of getting killed in traffic and increase your chances of dying of heart disease many times over.

Finally, as I said in my original post, a major key to cycling being safe is for lots of people to do it. Presumably then it's viewed as a legitimate activity, and you have fewer jackasses saying they "don't need to know the laws".

Matt said...

I agree that cars don't respect bicyclists nearly as much they should--especially around where I live in Massachusetts. I am usually quite nervous when biking in traffic around here.

Part of the problem is that bicyclists themselves don't respect traffic laws. I've found it hard to convince someone who doesn't bike much (Heidi) that bikers deserve the full rights of cars when they don't also accept the responsibilities. Some examples:

a) Not stopping at stop signs. This is less irritating when there is no traffic around, but particularly annoying when bicyclists don't even slow down.

b) Running red lights. Even at very busy intersections in Cambridge bicyclists seem to slow at red lights in hopes of running them rather then actually just stopping and waiting like they're supposed to.

c) Doing either a) or b) in heavy traffic such that they continually pass traffic that has just recently passed them. It's one thing if cars really are going more slowly than bikes, but where I live that is rarely the case. Passing bikes once is annoying enough--passing them two or three times because of all the red lights they run really loses any goodwill my arguments with Heidi had managed to gain.

d) Not yielding to pedestrians in crosswalks. Cars don't do this around here, either, so it's not a car vs. bike thing, but it's still annoying.

e) Blowing by pedestrians already in a crosswalk. This doesn't happen that often, but it's not only annoying, it's dangerous.

Either a significant portion of the bicyclists around here are themselves unaware of the rules of the road or they just don't care. Just the other day Heidi and I noticed a bicyclist stopping at a red light on a hill near our house (it's our bus stop, so we spend ~5 min a day there every day we go to work).

A proposed bicyclist's bill of rights would provide bicyclists with more well protected rights to the road in exchange for bicyclists being required to follow the same traffic laws as cars. Of course, , so bicyclists and drivers will continue to hate each other without any legal recourse.

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