29er Mountain Bikes
If you are looking for an efficient, stable and fast mountain bike, 29-inch wheels might be for you. Whether you are looking to race, ride rougher trails, a stable first bike, or something for commuting, 29-inch wheels are what you want.
Ideal Rider. If you are after excellent efficiency and better rolling speed, a bike with 29-inch wheels will suit you perfectly. 29-inch wheels roll for longer with less effort. Commuters love a 29-inch hardtail for their comfortable riding position, and racers love 29-inch wheels because they roll over obstacles easier. This enhanced stability and smoothness means you can go faster with minimal extra effort.
Ideal Terrain. Riders riding over rougher terrain with rocks, roots and bigger drops will love 29-inch wheels. The greater momentum of a 29-inch wheel increases stability and momentum, so 29-inch wheels hold lines a lot easier. Bigger rocks and trail features affect a 29 inch wheel a lot less, and thanks to a bigger attack angle, they roll over everything. Commuters love the 29-inch wheels because they roll for longer, provide a comfortable ride and are extremely reliable.
Acceleration and Speed. Larger wheels accelerate slower than smaller wheels. This is due to larger wheels having more weight farther from the wheel's center, resulting in higher rotational mass and requiring more effort to get up to speed. However, once up to speed, the 29-inch wheels will maintain momentum for longer and track better over the rougher terrain. With larger wheels, you can maintain higher speeds with more stability and greater efficiency.
The drawbacks are that 29-inch wheels take more effort to change direction, they can be less agile in the tight trails, and they can be sluggish to get up to speed. Modern frame geometries have aided in masking these cons but, if you want a more agile, poppy, quick feeling bike, then the 27.5-inch might suit your needs better. If you are looking for speed, stability and efficiency, 29ers are for you.
Traction. Thanks to the bigger diameter, 29ers have a greater surface area which provides better traction. While 27.5" bikes aren't necessarily bad in this realm, traction is suitable for most purposes if you plan on riding over slippery rocks and roots. In addition, the extra traction means you can corner harder, push the bike's limits further, and trust the bike more.
Comfort and Ride Quality. The attack angle is the angle formed when a wheel touches a square object. The shallower the angle, the better the rollover quality is. A better rollover means the wheels will roll more easily over any object (think of a basketball vs a golf ball). 29er mountain bikes have an advantage here, as their attack angle is slightly shallower (like a basketball), which means they are better at riding over roots, rocks and logs scattered around on the trail. The larger wheels "iron out" the trail making them easier to ride in terms of skill and energy. You can ride further, over more obstacles and with a greater sense of security.
Weight. 29ers are bigger wheels, so naturally, they weigh more. However, while this weight may mean they are harder to move, it contributes to them rolling longer. It helps keep the wheel planted, tracking on the right line and sticking to the ground.
The negatives here are, 29ers are harder to change direction, pick up off the ground and slower to accelerate. If you want a sharp, accelerating, punchy bike, then 27.5-inch is for you. On the other hand, if you are looking for a bigger, more heavy-hitting, stable, and fast in a line bike, a 29er is your choice.