In mountain biking, choosing a wheel size is akin to choosing a sports team. There are advocates for both 26-inch and 29-inch wheels, and the debate continues in manufacturing and competitive arenas. Mountain bikes have traditionally used 26-inch wheels, but the introduction of the "29er" with larger 700c-sized wheels and tires uprooted this legacy and now dominates so much of the market that it could replace 26-inch wheels altogether. For now, each wheel has a place in different styles of mountain biking because of the distinct riding characteristics each provides.
Small Wheels, Big Impact
The first dedicated mountain bikes made use of 26-inch wheels, and the advantages they provided over larger wheels aligned nicely with mountain bikers at the time. Because a 26-inch wheel has a smaller circumference than a larger 700c wheel, the rim is structurally stronger and resists deformation from impact. Wheels that are 26 inches excelled at handling hard drop-offs and even crashes without losing their true. A 26-inch wheel also has increased maneuverability when compared with a larger wheel, which can be advantageous for technical riders on difficult courses.
Rise of the 29er
Bikes with 29-inch wheels use the same rim size as a racing bike, the 700c. This 622-millimeter wheel size has excellent rolling resistance, providing more speed to the traditionally sluggish mountain bike. The larger wheel size brought other advantages, too; a larger circumference means there's more tire in contact with the ground at all times, increasing traction. The larger 29-inch wheel also had less trouble rolling over larger obstacles than the traditional 26-inch wheel. The improvements to material strength and the advent of high-strength carbon fiber made the loss in durability compared with the 26-inch wheel much less of an issue, contributing substantially to the meteoric rise in popularity of the larger wheel size.
Choosing a Wheel
Wheels that are 26 inches remain the gold standard for certain types of mountain biking. Downhill bikes, the most durable mountain bikes in production, use huge suspension clearance and high bottom brackets to descend the toughest hills at dangerous speeds. These bikes feature the 26-inch wheel size because of the strength increase of the smaller wheel. The increase in maneuverability also comes into play for technical-riding competitions such as mountain bike trials. Trial bikes use 26-inch wheels for the precision and handling at low speeds on challenges such as rock gardens.
Go Big or Go Home
The 29-inch wheel is now near-ubiquitous for traditional cross-country mountain biking and most mountain-bike racing. The larger wheel simply offers key advantages to speed and capability that are hard to ignore. The reduced rolling resistance makes the 29-inch size ideal for long-distance riding and racing, because it increases the speed of the bike. The loss in durability and maneuverability are considered negligible, because the bike is still enormously capable in both categories.