Bigger might be better when it comes to mountain bike wheels.
At one time, mountain bikes had 26-inch wheels and riders seemed content with their ability to roll over whatever lay ahead. But even before mountain biking boomed nationwide in the 1990s, bike makers were wondering if a bigger wheel might better serve the purpose of rolling over rocks and roots, climbing up steep hills and screaming down sharp drops. Bikes with bigger 29-inch wheels began trickling out in the 1990s but didn't achieve mainstream status until the past decade. Ever since, mountain bikers have been debating the pros and cons of big and small wheels.
Initially, mountain bikers were concerned that 29-inch tires were too big to make the tight turns common on most singletrack trails. This perception may have been fed by the wider handlebars that seemed more common on bikes with 29-inch wheels. In fact, many riders now believe that 29ers handle tight trail as well, if not better, than 26-inch bikes. They argue that the bigger tire is wider as well; as a result, more tire is in contact with the trail than on the smaller 26-inch wheel. Thus, there's more tire gripping the trail, making cornering more stable and secure.
Bike guru and author Leonard Zinn says the 29er gives the feel of having more suspension, especially on downhills, as it seems to roll over obstacles that the 26-inch вЂњbike dropped into or bounced back from.вЂќ The bigger tires also proved less susceptible to off-camber obstacles that were more likely to bounce the smaller bike back and forth. Drainage troughs, for instance, or tree roots are less likely to twitch the bigger 29-inch wheel.
As might be expected, the bigger 29-inch wheels can take a little more effort to get rolling; you might find yourself starting in a higher gear than you're accustomed to. But once those big wheels get rolling, the resulting momentum is your friend. This is especially true on downhills, where the added stability of the bigger wheel can make for a faster, yet less harrowing descent. As for climbing, momentum is more easily maintained thanks to the better grip resulting from more tire grabbing the trail, especially the rear tire responsible for translating your pedal power to propulsion.
The 29er is bigger and tends to go faster, resulting in more work for the brakes. Thus, you might want to be more particular about the brakes you have on a 29er. Stronger disc brakes are recommended over V- or pull brakes. Hydraulic disc brakes are often recommended for downhill bikes of any stripe, while mechanical brakes are generally capable of doing the job for most cross-country riders. However, because of the greater stopping demands of the 29er in general, hydraulic brakes might be well suited for more aggressive cross-country needs, especially for bigger riders.
Best of Both Worlds
A few bike makers flirted with the idea of marrying the best of both worlds, a 26/29 creation that came to be known as Frankenbike. Trek, for instance, offered its 69er - 26-inch wheel on the front for tight turning, a 29er on the back for grip - for a few years. The latest salvo in the wheel wars is the 27.5-inch wheel, a compromise between the 26-inch wheel and the 29er. At least 10 bike manufacturers are scheduled to roll out 27.5-inch bikes sometime in 2013, claiming they offer the agility of the smaller 26-inch wheel with the roll-over-anything gusto of the 29er. It's too soon to tell if the 27.5-inch wheel is the ride of the future.