Change, it is often said, does not happen in a vacuum. One shift in thinking can lead to a concurrent reaction in behavior, which can lead to a domino-fall of consequence that eventually can reshape the way we all act and think. Cause and effect, action and reaction, ripple outward and create more cause and effect, more action and reaction. Whether we are talking about species evolution, politics or bike design, this holds true.
A few years ago, I opined that the pendulum of mountain bike geometry was swinging past one of my favorite navigation points—the Schwinn Excelsior DX—back in the direction of slacker head angles after a couple decades catering to a decidedly steeper, cross-country-race-friendly emphasis. I also speculated that we were reaching the end of the pendulum’s swing, as the head angles and reach numbers on general-duty trail bikes were getting into what had been the sole domain of downhill bikes not too many years prior. The thick part of the mountain-bike-buying bell curve, I assumed, would balk at these new plows. Turns out I was wrong (yet again, just like when I said elastomers would be the future of suspension …), and the pendulum has continued to swing out into the long-and-slack frontier. How? Why?
The evolution of bike geometry is an ongoing and collaborative/competitive experiment. Manufacturers are looking to sell bikes. In order to do that, they need to sell bikes that people want to buy. The first mountain bikes were modelled after old Schwinn cruisers because that was as sensible a starting point as any. For a time, XC riding and racing was seen as the dominant market, and so bike design moved from heavy and slack toward light and steep, head angles ratcheted up, and nobody seemed to mind wearing Lycra. Then, Canada, freeride, yada yada yada, and large numbers of mountain bikers began thinking that this was more fun. Cue widespread carnage defined clearly in broken helmets, collarbones and bike frames. Steep, twitchy bikes climb tight, nadgery trails well, and they are rockets going up fire roads, but they pretty much suck everywhere else. So, head angles got slacker, wheelbases got longer, tires got wider, wheel diameters expanded and here we are. But there are some nuanced points along the way to consider.
One of the prime indicators of the coming change, if you were to look back a decade-and-a-half, would be the return of the riser bar. Not only did riser bars come back, they got wider. And wider, and wider again. Hand in hand with that, by necessity, stems got shorter and shorter. Narrow bars and long stems work pretty well together, but wide bars and long stems, not so much. It creates an odd tiller effect at the front of a bike. Likewise, narrow bars and short stems are grim. A short stem needs some more bar width to influence a front wheel to turn. Meanwhile, slacker head angles were being met with greater fork offset. This was seen as a way to keep trail (a measurement derived from the fork