April 25 2013 by Jason Fogelson
Another dive into science today in an effort to figure out how this whole motorcycling thing actually works. I am not a scientist. I don't even play one on television. So, I have to really start with the basics in order to understand scientific concepts. Luckily, gyroscopic force is a pretty easy one to explain and understand -- and it's one of the major forces at work keeping motorcycles upright and safe to ride.
First, a few definitions. A "gyroscope," according to Merriam-Webster's Dictionary Online, is "a wheel or disk mounted to spin rapidly about an axis and also free to rotate about one or both of two axes perpendicular to each other and to the axis of spin so that a rotation of one of the two mutually perpendicular axes results from application of torque to the other when the wheel is spinning and so that the entire apparatus offers considerable opposition depending on the angular momentum to any torque that would change the direction of the axis of spin." The "opposition" that the definition describes is what's known as "gyroscopic force."
On a motorcycle, the wheels act as gyroscopes, spinning rapidly about an axis. The front axle of the bike is connected to the front forks, and the rider applies torque to the forks in order to turn the wheel. Here's where the gyroscopic force comes into play.
Once your bike is rolling along above about five miles per hour, the wheel develops gyroscopic force, and will resist turning or tipping over. The wheel wants to go straight, and it wants to remain upright, in line with the force of gravity. You can feel this phenomenon while you ride -- it's pretty magical. Because of this resistance, steering your bike is a little bit counterintuitive. Okay, it's a lot counterintuitive. Pushing on the right handlebar causes the front wheel to lean to the right, in opposition to the gyroscopic force, and the bike steers to the right. If you were paddling along in a parking lot at a walking speed, you would turn your wheel to the right -- pulling on the right handgrip -- to steer right. At speed, the action is exactly opposite, thanks to gyroscopic force.
Why is it important to know this? Just the other day, I was on a group ride. One of the riders was less experienced than the rest, and I noticed that she was having difficulty maintaining her line in curves, especially at freeway speeds. It led to a few hairy exits, and I could tell that she was a little rattled when we stopped for a break. She wanted to avoid the freeways and higher speeds, and stick to side streets, and she asked me for advice. I quickly realized that she had never been introduced to the concept of gyroscopic force and counter steering, and I gave her a quick explanation. I advised her to slow down upon corner entry, and not to be afraid to push on the inside grip when she was making a turn. "Get a feel for it, and trust gyroscopic force to keep your bike upright." We took a ride on some quiet streets, and I coached her through some turns. Very quickly, she got the feel for counter steering, and began to trust gyroscopic force. I hope that she'll continue to explore and improve her riding -- I think she's got a really good start on the process.
There's good information there for expert riders, too. We've all had the experience of entering a corner a little too hot, no matter how carefully we ride. That's when you have to trust your bike, push harder on the inside grip and let gyroscopic force do its job, keeping your bike from falling over and bringing it back upright when you've completed your turn. Situations will arise in every rider's experience, and having a firm intellectual base to support your actions helps keep panic from ruling the day. Old reliable gyroscopic force operates all the time. Know it, embrace it, love it and ride safely.