I teach folks how to ride bikes. That's what I do for a living. I teach beginners who've never sat on a bike before, experienced racers who've been racing for years, and everyone in between. I think I've just about seen it all when it comes to learning to ride.
Anyways, I've got a few theories about why we progress at different rates.
The first has to do with your athletic history. I firmly believe that if you've mastered any balance sport (skiing, skating, cycling, sky-diving, dancing, etc), you can easily pick up another balance sport. By mastery, I mean that you understand the principles behind balance and weight distribution. Afterall, cycling (and other balance sports) are all about balance and weight distribution.
How many of you really understand why your bike stays upright when it's rolling? Or why it's more stable leaning through a turn? Or why you should sit behind the saddle during an emergency stop or a steep descent? Do you realize that you steer your bike with your hips (not your hands)?
Unfortunately, most new riders never take the time to learn the basic prinicples behind the sport -- balance and weight distribution. Instead, they learn the more intricate "tricks" of the trade -- cornering, descending, steering, taking one or both hands off the bar, etc. All fine and good, but these are the icing on the cake. These are the implementations of those two basic principles. And if you never really understand those two principles, you'll never really master cycling.
Okay, that's theory one.
Now, on to some other thoughts.
We all learn differently. Some of us have more outgoing personalities than others. Some of us like risk. Some of us have fear or are timid. Some of us are very analytical. Our personality affects the way we approach the sport. While being conservative may prevent you from crashing, it will most likely also prevent you from really understanding how to push your limits and also to understand how the bike works.
Many of us also never receive instruction in how to ride. Everyone knows how to ride a bike, right? Or, we just get tips from the older gentleman in the club who's been riding for 40 years (whether or not he really knows what he's doing). Participating in a skills clinic or private instruction with a coach is the best way to learn how to ride a bike. If we want to learn to golf, we take lessons. Same with tennis and skiing. And the same should be true with cycling, however I can't tell you how many people I know who mistakenly think they know how to ride. We certainly wouldn't try to drive a car or ride a motorcycling without instruction. Why do we try to ride a bike without learning how to do it properly?
Most of us just get on the bike and ride. We might learn a little more about HR or cadence or even proper skills, but we never practice those things. If you want to learn to descend like an ace, you need to learn to counter-steer like a pro and be able to do it at speed (20+ mph). To do that, you have to go to a parking lot and practice. A lot. Frequently. If you do take a clinic, you need to practice your skills until you really understand them.
Whew! Can you tell I'm passionate about this? I see so much potential on the road. I believe just about anyone can become a skilled, confident rider. I wish each one of you could take one of my clinics -- you'd be amazed at what a difference you'd see in your riding.