Another Angle on 29ers
Imagine a skateboard wheel running over a series of 1" bumps. Since the skateboard wheel has a radius of only an inch, the wheel has to move 1" vertically in just 1" of horizontal motion every time it contacts a bump. This is an abrupt change, or high angle of attack has drastic effects on the rider's motion. With a 20" BMX wheel, that same 1" of vertical motion happens over about 4" of forward motion. This turns what was a radical bump into a mild annoyance. Now ride over the bump on a 26" wheel, and you have almost 6" of horizontal distance to spread out the impact. The bump is hardly noticeable. Not only does the bump disturb your riding less, but it also has less effect on your speed. Bigger wheels maintain your momentum. This effect is somewhat similar to that of a suspension fork, except that it happens on all bumps, regardless of suspension fork tuning. Tire pressure changes the effect somewhat, but with the same results regardless of tire size. Since riding off road is normally on less than smooth surfaces, the effect of a larger wheel is constantly enhancing the ride. If both wheels are larger, the effect works on both ends of the bike. On the Fisher 29ers, you'll notice this effect in two ways. First, the bike will ride smoother and more comfortably. Second, the bike will be slightly faster, especially on broken or rough ground.

Bigger Wheels Have a Longer Contact Patch
The contact patch is the amount of tire you have on the ground at any one time as the wheels goes through its rotation. As The diameter of the wheel increases from 26" to 29", the shape of the contact patch gets longer. The benefits of this are noticeable. For technical climbs, the added length increases traction as the rider can shift their weight more freely without losing pressure on the contact patch. In addition, the increased contact patch length on a 29er benefits the rider when cornering in uneven terrain as the tire will want to stay in contact with an obstacle and not skip over it. Last, in mud, sand or snow, the longer contact patch can help keep the tire on top of the surface as opposed to sinking in and bogging down. Think about snowshoes. They are designed to keep you on top of the snow, where the going is easy.