Here is a really good Mercedes-Benz Kris Holm Article and Video!
The development of the bicycle since the 1800s has amounted to a science when it comes to picking out your mode of transportation: trekking bicycles, commuter bicycles, freight bicycles, time trial bicycles, BMX bikes, and countless of others. But if we follow this progression, a distinct tangent peeled off during the late 19th century. In the 1880s, the penny-farthing or the high wheel, simply known as "bicycles", gained popularity in the Western world and had cyclists riding high and nearly directly over the front axle of a relatively large front wheel. However, many owners discovered that they could simply ride the front wheel and handlebars, dispensing with the secondary wheel and the rest of the contraption. Experts count this modified version of penny-farthing riding as the origins of the contemporary unicycle.
The unicycle, however, remained within the boundaries of circus entertainment and private enthusiasts while the bicycle took the stage lights in popularity and turned into a widespread sport in itself. That is, until recently. One of the swiftest growing forms of unicycling is on rough terrain, known as "mountain unicycling", which comes with it's own specialty unicycle. Mountain unicycles differ from the standard in that the tire diameters are larger, either 24 or 26 inches, allowing the rider to traverse across any trail or surface that a mountain bicycle is capable of handling. In light of such rough terrains, the saddle of a mountain unicycle is also thicker and more comfortable. Mountain unicyclists train to maneuver, balance, and react to anything from rocky slopes and dirt to snow and ice as well as drops, bridges, and walls. Meet the one-wheeled dare devil, Kris Holm, who seems to have no fear in pushing this sport to the limit (see video above). A pioneer of the sport, Kris has ridden technically difficult terrain in 15 countries, including trade routes in the Himalayan Kingdom of Bhutan and on the Great Wall of China. In 2006, Kris climbed and attempted a unicycle descent of Licancabur, a 5950 m volcano in Bolivia. Kris was the first rider to bring mountain unicycling to a mainstream audience.
The construction of a unicycle isn't a complex one as it consists of a few key elements: a saddle, a seat post, a forked frame, pedals, cranks, and the wheel inclusive of tire, tube, rim, spokes, hub and axle. The actual mastering of riding a unicycle is a different story altogether as Mr. Holm explains in the video. In theory, a unicyclist is always subconsciously aware that they are at a state of imbalance. The unicycle by itself lacks stability when stationary on its own. The rider then adds the core strength, balance, and agility needed to bring the wheel under their center of gravity and thus correct the rider-unicycle system into a state of upright equilibrium. This process of centering weight is the basic stabilization move called "idling." The next feat is obviously motion. This necessitates that the rider incites the wheel's rotation through pedaling, thus displacing his centering from the contact point between wheel and ground. Simply put, it's a voluntary decision to "fall" in the direction the rider wishes to move. Balance is again lost, until the rider almost immediately regains centering while accelerating forward or backwards.
Unicyclists such as Kris Holm have long since mastered the basics and are now pinning their skill against nature as they roll, skid, and jump over roots, rocks, and vertical drops. Some of the other unique tricks possible are 360 degree air spins, over six foot drops, leaping over two foot barriers while descending, riding up and down stairs, and gliding without brakes on steep slopes. The major advantage of a unicycle over a bicycle is the ability to turn on a dime and fit through narrower spaces.
If this peaks your interest and you're determined to start your one-wheeled balancing adventure, mountain unicycles can either be spotted at specialty bicycle shops or ordered online through such companies as unicycle.com. Such stores offer entire unicycles for purchasing as well as specialty frames and parts, protective gear, and accessories. Experts agree that aside from design and quality, strength is one of the most important qualities for off road riding when picking out your unicycle. Once you've picked out the one you desire, work on your balance first before attempting to jump down a six-foot wall. Safety first, then with determination, pedal your way up to Mr. Holm's dare devil status.
More about Kris Holm’s adventures: www.krisholm.com