If you are already into the bike world you probably already know this, but with each bike type, BMX, mountain, road, comfort, has a completely different culture. Most people, when they get into biking, choose a style, and stick with it. Road Bikes hang out with road bikers, mountain with mountain, BMX with BMX and so on. Even within each group there are subcultures, that occasionally clash. Personally I would just like to add that I believe everyone is entitled to their own personal styles when it comes to the bicycle world. If you want to put 700c tires with studs on your carbon Fuji SL, I’ll admit it would be unusual, but it makes no difference to me. No type of biking is inherently better or worse than any other, in the end all bikes are just two wheeled machines. Ok with that said I’ll answer the question of what kind of bike you should buy, and in order to answer that you need to answer what do I want?
If your key word is casual, then a comfort/hybrid bike is the way to go. Nothing too serious component wise so it is not a big punch to the wallet, and there are plenty of choices depending on what you are looking for. Casual rail trails? Try something with a little more tread. Commuting? maybe slicks with flat bars. Looking for more comfort? Try a pedal forward bike. This kind of bike is also a popular bike for people with back, hip or knee issues.
If you are looking for intense fitness, and or community, the style would have to be road or mountain bike. I will try to make the distinction between the two as simple as possible, so forgive me. The easiest way to see it is the ‘high’ you get on the bike. Endurance training is more of a runner’s high, due to an endorphin rush. Mountain biking is more adrenaline based, it gives you an amped up feeling. I find younger folks tend to be drawn to the adrenaline side and older folks tend towards the endorphin side. Both road biking and mountain bikes share both adrenaline and endorphins, just on a gradient. Downhill mountain bikes is mainly adrenaline based. But cross country mountain biking is very much endorphin based. Granfondo races (RB) are high endorphin content and low adrenaline, but crit races (RB) are a adrenaline fueled. With so many choices it is pretty easy to find something that suits you.
Finally is BMX. BMX is a race bike or a trick bike. This is not for the average joe. While it BMX does not require as much endurance but it requires an enormous amount of bike handling skills. This is the kind of bike I would recommend to a skateboarder who is trying to get into bikes. Something you can bring to the skate park, and eventually, if this is the direction you want to go, there are BMX races on small dirt courses. The nicest thing about BMX is they are low maintenance and almost indestructible. Since they are so durable and mostly one size fits all they are very popular as kids bikes.
I don’t think that anyone ‘has’ to be subject to one type of biking to another. I often times feel like just cruising around the neighborhood in which case I take my Crosstown. Sometimes I want to go fast and put down some serious miles, in which case I would jump on my road bike. In fact moving between the types of bikes has made me a more rounded rider. I have incredible endurance in the woods thanks to my road bike and my bike handling skills on the road improve thanks to my mountain bike. I guess to finish this post off I would just say that there is a bike out there for everyone, I truly believe this. In this day and age whatever you want in a bike, from time trials to enduro riding to BMX racing, there is a type and style that fits you, it’s just a matter of figuring out what you want.