Choice is generally a pretty swell thing, as Wendy's so brilliantly showed us some number of years ago.
Not too many people really remember it, but for most of the '90s, the mountain bike was king. Americans who'd gone to race in Europe like Joe Parkin and Bob Roll came home to ride dirty in the exploding mountain bike circuit. Trailheads were packed, and mountain bikes outsold road bikes 10 to 1 or more. There was also lots of neon and many other unfortunate things going on, but they were really trappings of the time more than the activity.
Circumstances conspired to end these heady days, including but not limited to Lance Armstrong's tour wins and trail user conflicts and some others that I'm not aware of. One big factor was the over specialization of equipment - it became a technology driven game, where unless you had the absolute latest and greatest purple anodized, CNC-machined whatnots, you just weren't in the frame. People get sick of that - FAST. Arms races don't turn out very well for anyone involved - even the arms dealers eventually get blown up.
Today, relative simplicity reigns once again. Mountain biking got cut VERY low, but has been steadily climbing out of the hole. A lot of this has been driven by the emergence of the hard tail 29er. Yes, 29ers are NEW and TECHNOLOGY and a DIFFERENT STANDARD than the old standby 26" hardtail. They are also reasonably simple, generally use very reliable parts that are no more complext to work on than road bike stuff (hydro brakes are actually pretty easy to work on), and most importantly allow most competent riders to feel like they can ride well on the terrain they most want to ride on and are leagues more comfortable than their hard tail 26" equivalents.
We could explore the niceties and nuances of 26 vs 29 for weeks and months, but the simple fact is that 29er sales have exploded in the last couple of years in a way that no category has broken out in a long, long time. Sales successes like that are great for manufacturers and bike shops, yes, but they also mean that more people are getting out there and enjoying riding on a bike that they were enthusiastic enough about to go out and get one. That's the dog - the sales success and everything is just the tail that wags.
Mountain biking has been a niche composed of niches - hard tails, xc full suspension, all mountain mid travel, downhill long travel, rigid, singlespeed, rigid singlespeed, full suspension singlespeed - all in your choice of 26" or 29" wheels. If you're in the market for a front wheel, you'll only need to know a few things - UST or not, centerlock or 6 bolt, and 9mm QR, 15mm through axle, or 20mm TA? Simple right? Rear is even easier - UST or not, centerlock or 6 bolt, 135x10mm or 142x12mm - or maybe something else. You have to be a pretty serious bike nerd to know what you're after with this stuff, but despite all that, it grows. People who I ride with, who know of my reborn fire for riding dirty, are all over me about mountain bike this, mountain bike that. And when you get into it, they're asking about simple, quality hard tail 29ers. That's what they mean when they say "mountain bike."
I got home from a really fun ride in the woods with three other guys on Sunday morning (two of us on front suspension geared 29ers, 2 of us on rigid singlespeed 29ers), and I remember "oh the mountain bike world cup in South Africa was yesterday, I wonder who won." Nino Schurter won, as he did last year. Unlike last year, when he won on a 26" hard tail (the Euro pros have, until last year, been DIE HARD about staying on 26" hard tails), he won this year's event on a 650b-wheeled hard tail. 650b you ask? For those times when a 29er is too much and a 26 isn't enough, a 650b is apparently your go to move. I just about cried.
I'm pretty simplistic about gear. I like having a road bike, and a cross bike, and a mountain bike. And I'm a pretty gigantic bike nerd. If someone comes up and says "I want a mountain bike, please!" and you confront them with some 2 to the n conflagration of about a gajillion and nine configurations, they're going to say "just kidding" and turn around.
Schurter's team made this choice based on getting the .01% edge on the course that will be used for this summer's Olympics. There's nothing in it that's about "this is the right thing for the way most people ride bikes." Also notably, the first two women in the SA world cup results rode 29ers, while third rode a 26" hardtail. Asked if wheel size had anything to do at all with the results, all three said "absolutely not." Unfortunately, there is a game of telephone that goes on, where the pursuit of that .01% by the people whose skills and fitness are in the .01% group, by the time it gets filtered down to the forums, becomes "I heard some guy's 29er burst into flames when his friend bought a 650b."
For what it's worth, Schurter's team mate and wheel size mate DNF'd in South Africa. With a wheel mechanical.
This is the point where someone outs me for my evil ulterior motive. Yes, we have a 29er frame picked out. Other than time and pretty short money, we don't have a ton invested in the project. If that segment falls apart, from a business standpoint, fine. We've got 29er wheels good to go, but each of the rims we use also comes in both 26" and 650b sizes. Other businesses don't have it so good. One HUGE reason why people are buying mountain bikes now? Because shops can commit to them and know that there's drive behind them, that they won't become white elephants when the next format du jour ("oh that sounds good, I'll have that") comes along. I would bet that top dealers all over the country are firing off "if you advance this 650b silliness, I WILL NEVER BUY ANOTHER MOUNTAIN BIKE FROM YOU EVER AGAIN" emails en masse. It's all too common to go into shops now, even with all of the momentum that mountain biking has gathered over the last few years, and hear "yeah, we really don't do too much with mountain bikes." Now that shops finally feel that they can be in the mountain bike game again without becoming full on specialty boutique mountain bike specialists, if the world puts another format shock in front of them, that will be the definitive end of buying a mountain bike at your friendly neighborhood bike shop. And that makes mountain biking a non-viable segment. And that would make me sad.
Here's the video of the men's race last weekend. It's a great watch.