Bigger wheels roll better and absorb bumps and other obstacles more easily. But they are heavier, take more effort to accelerate, have softer sides and require longer forks and chainstays, making bicycles a little heavier.
Especially with full-suspension frames, the transition to 29ers wasn’t without issues. The significantly larger wheel diameter had a negative effect on the suspension kinematics. Simply put, long-travel suspension is not possible with this size.
But with classic 26-inch wheels suddenly unfashionable, the industry had to come up with another solution for long-travel bikes. Its answer was to revive a wheel size that had disappeared from the market years ago: the 650b, or 27.5-inch wheel.
One remarkable, and often overlooked, result of this shift to larger wheel sizes is that weight no longer dominates the conversation about mountain bikes.
That is no great loss, as weight is overrated in general. Saving 200 grams is ridiculous when the total system — bicycle and rider — weighs 70 to 90kg (155 to 200 pounds). It makes even less sense when the cyclist is riding on underinflated tires because he neglected to pump up the inner tube.
Marketing trumps reason. For better or worse, big wheels are now a must for everyone. That benefits many riders, unless they happen to be short.
Over the years, a few innovative bicycle manufacturers have tried a more reasonable approach by adjusting the wheel size to the size of the cyclist. A road bike with a frame smaller than 51cm is more harmonious when paired with 26-inch wheels. In addition, there is less toe overlap, so the bike not only has better riding dynamics but is safer as well.
On the other end of the size spectrum, many forget that the German company Heidemann once built everyday bikes in large frame sizes with 30-inch wheels. Although there are clear technical advantages to offering smaller or larger wheels depending on a rider’s size, both extremes have disappeared from the market. In Heidemann’s case, the entire company disappeared.
Instead, marketing has succeeded where reason has failed. The marketing machines behind mountain bike brands have accomplished a surprising feat: No matter whether the cyclist, and thus the bike frame, is tall or short, a hardtail is a 29er and a full-suspension bike has 27.5-inch wheels.