One of the conclusions that seemed quite counter-intuitive to me is that on dry pavement, the front brake alone will stop a bike faster than both the front and rear brakes applied together. It’s easy to understand that under hard braking, the rider’s center of gravity shifts forward, significantly unweighting the rear wheel. As a result, the rear wheel has little traction and can’t help much with braking. But why would using the rear brake actually diminish braking performance? The article doesn't completely answer that question, but I get the impression that it has more to do with human psychology and physiology than with physics. That is, when we brake with just one lever, perhaps we’re better able to focus our effort on stopping the bike safely and quickly.
Jan was convincing enough in the article to get me to consciously shift my behavior from using both brakes most of the time to almost exclusively using the front brake. I still use the rear brake in certain situations, like when signaling with my left hand, braking on slipper surfaces or controlling my speed on a long descent, but otherwise I've been almost exclusively using the front brake lately.
Using the front brake alone is a bit unsettling at first for some who don’t have a lot of cycling experience. It’s easy to imagine braking too hard with the front brake and something like this happening:
Recently I did some real world testing of my own on this whole over-the-handlebars issue. My methods may have not been up to the same standards as BQ, but I think I came away a little smarter none-the-less.
I was coming home from work on the Burke Gilman trail, riding my single speed Trek 311 which lately has been set up with a fixed gear drivetrain. I'll admit I was going faster than I should have been as I approached an intersection between the trail and a road that generally sees very little traffic (actually, I was going about as fast as I could, trying to squeeze in some interval training on my commute home). At this particular intersection, it's very difficult to see a car coming until you're almost into the intersection. I was leaning forward, stretching my neck out trying to see around that corner a fraction of a second earlier so I wouldn't have to lose any momentum. Unfortunately what I saw just as I entered the intersection was a car on a perfect T-bone collision course with me. There was no time to thoughtfully reflect on the BQ brake tests or to consider which brake lever would stop me quickest. It was complete instinct and muscle memory that grabbed the front brake as hard as it could.
Okay, let's pause to review some of the facts we've learned so far:
- I was going pretty fast. Definitely over 20 mph.
- I was leaning forward on the bike, trying to "see around the corner." (yeah, like that's really going to help)
- I was riding a fixed gear bike.
Back to my story. So as you can imagine, the same instinct and muscle memory that caused me to grab the front brake with all my might also told my feet, "STOP PEDALING NOW!"
You can see where this is going, can't you?
In what seemed like a nanosecond I felt the back wheel of the bike lift up as I went somersaulting over the handlebars and landed on my head and right shoulder on the pavement directly in front of the car. All I remember about the impact is the deafening crunch of my helmet and body striking the pavement. There was none of the super cool time-freeze effect that Joseph Gordon Levitt's character experiences in Premium Rush. No weighing of options, no super slo-mo flight through the air. Just a loud crunch.
With my right clavicle in four pieces, four sprained fingers, and a number of other bumps, scrapes and bruises, I dragged myself and my bike out of the middle of the road and sat down next to the trail to take inventory. I knew immediately my collarbone was broken. I've broken a couple of bones before and there's a certain unmistakable feeling when your bones aren't all where they belong.
I never lost consciousness, but between being in shock and most likely having suffered a mild concussion, my memories of the first few minutes after the crash are fuzzy. I know the driver of the car got out and asked if I was okay, but I have no memory of whether they were male, female, young, old or what kind of car they were driving. I apparently convinced them I was okay, because they left me sitting by the trail trying to work out my next move. The next move of course was to call Sarah and ask sheepishly, "can you come get me and take me to a hospital?"
Okay, so what did I learn from this experience? I'm still trying to figure that out, but here are few things that come to mind:
- Sometimes I can really be an idiot.
- It takes about 12 weeks for a fractured clavicle to heal completely and during that time you get to see some really breathtaking bruises.
- It's difficult to shift your weight back quickly on a fixed gear bike.
- When your head hits the pavement, a helmet is a good thing to be wearing.
- Leaning forward to peek into the intersection as you approach is not the same as slowing down.
- Blowing through an intersection at high speed just because there "usually" aren't any cars there is a bad idea.
The key is having that time to prepare. So, if I learned nothing else from this experience, hopefully I at least learned to pay attention and always be prepared to stop when approaching uncontrolled intersections. In other words don't act like I'm Joseph Gordon Levitt in Premium Rush because, duh... that's not real.