I first saw this expression on a T-Shirt at a motorcycle dealership. I suspect it was meant to be interpreted as "If I have to explain why I ride this brand of motorcycle, you wouldn't understand". But, this same expression could be used more generically by anyone who has trouble explaining why they engage in certain activities... like motorcycling.
What is it about the joy of motorcycle riding that makes it so hard to explain to others? If you ask any motorcyclist why they ride, you'll likely get an answer like "It's fun". It's as though that simple explanation is all that's required for anyone to understand. It's not that simple. "Fun" means many different things to different people. An activity might be fun for one yet downright frightening for someone else or even boring for another. Let's have some fun... Ask several friends to define fun. Is eating dinner with friends fun? Perhaps it's fun to go swimming. Is it more fun to go skinny dipping? Why? I once read someplace that motorcycling is the most fun you can have with your clothes on. Is it possible that a simple word like "Fun" is less well understood than motorcycling?
I prefer to describe the fun of motorcycling as exhilarating. Exhilaration is a step above fun. It implies a higher level of excitement. The rapid acceleration, the smells in the air, the view of the road passing beneath your feet, the sound of the wind rushing by mixed with the mechanical noises coming from your bike, and the feeling of the wind in your face all contribute to exciting your senses and adding to the exhilaration. But, these same things can contribute to a heightened sense of fear. And if someone's experiences have conditioned them to be afraid of motorcycling, this additional excitement will not be considered fun at all.
There are many pastimes that can be exhilarating. I tend to think of most outdoor activities as being fun and many border on being exciting and even exhilarating. Horse back riding, hang gliding, hiking, sky diving, mountain climbing, bicycling, bungee jumping, and I already mentioned swimming, all provide different levels of fun, excitement, and exhilaration or fear to different people. The difference between exhilaration and fear lies in a person's perception of the level of danger involved.
Motorcyclists understand that riding is dangerous. But, they have a tolerance for the danger based on their experiences. They're comfortable with their ability to avert danger by using their skills and confidence when needed. That's not to say they're all accurate in this assessment. Riders who underestimate the level of danger can contribute to accident statistics. Those who overestimate the level of danger, but continue to ride anyway, tend to get teased by the more adventurous riders for their choice of motorcycle or riding style. Of course the actual level of danger is dependent on the individual's own motorcycling skills.
A British researcher, studying accident statistics, proposed that people have different thresholds of danger that they're comfortable with. He theorized that people alter their driving habits based on their perception of the level of danger involved. When conditions change that increase the level of danger, drivers are more cautious to bring the perceived level of danger back down to their personal threshold. People drive more slowly when it's raining or snowing, or when their brakes need servicing. Conversely, when conditions change to decrease the danger level, many drivers drive more dangerously. He speculates that this tendency explains why safety legislation always falls short of the calculated impact on accident statistics.
So, if you're trying to understand why someone would engage in some activity that you feel is too dangerous, remember that we're all just trying to have fun. Each of us within our own boundaries seeks a little exhilaration. We all have different skills, reflexes, experiences, thresholds of danger, and opinions about risk factors. I used to ride a sport bike and enjoyed many years of riding around the mountain roads in my home state of Vermont, an activity that is regarded as extremely dangerous with the sharp turns, sand on the road, frost heaves, and narrow roads. I'm older now. Less agile and with slower reflexes, I now ride a Harley Davidson and I find riding without a helmet more exhilarating. Which brings me to another popular motorcyclist expression... "Let those who ride decide".