The Men and Their Bikes
Mountain bicycles are stronger than road racing bikes and are therefore heavier and have stronger and heavier componentry. They also have a wider range of gears because the grades seen and the speeds attained offroad are generally more widely varying. Mountain bikes also have more laid-back geometry. Riders sit more upright on a mountain bike because the aerodynamic advantage of a low riding position is much less at the low speeds of a mountain bike ride. Also, the head tube angles are generally slacker to put the fork more in line with trail impacts, which are nearly nonexistent on the road. Some riders, especially lighter ones, will use road race bicycle components on mountain bikes to save weight. A "hardtail" is a bike without rear suspension, and it typically has a front suspension. A bike with suspension on both ends is called "full suspension," one with no suspension at all is known as "rigid," and bikes with rear suspension and no front suspension are rare enough that they don’t have an official name.
My bike is a little bit special. It is a Flyte Celsius 9 frame built for 29" wheels, and I have outfitted it with a Cannondale Lefty single-sided strut fork. I started out with a Cannondale Jekyll, which was a stock bike straight off the showroom floor. I raced an entire season on it, and decided that the 5" travel full suspension experience was too heavy and inefficient for racing, so I decided to build up a hardtail.
I wanted to do it on the cheap, and I realized that I could convert my fork to work with the larger 29" wheels, and reuse everything on the Cannondale except for the frame and the 26" rims. However, the Cannondale fork is a proprietary piece using a non-standard oversized steerer tube, so to adapt the fork, I had to fabricate a smaller steerer tube and reduce the travel so that the fork would bottom out on its bumpstops instead of on the front tire. I was able to purchase the material for the steerer tube and a travel reducing spacer locally, and I used a lathe to fabricate the new parts. I also built my own wheels using lightweight road bike rims.
Since then, I have upgraded the entire drivetrain, and converted to tubeless tires, making a lightweight, dependable racing bike. The main difference between a racing bike and a more "civilian" bike is that race bikes tend to sacrifice some durability for light weight, or all-day comfort for efficient geometry, though this is definitely not always the case. The other main difference, of course, is price!
Kenneth Tsang
Both mountain and race bikes are designed to hold race weight person without too much flex or mechanical breakdown in as light a package as possible. That said, each is abused in totally different ways. Road bikes handle like a Porsche. They’re stiff, with very tight steering and very aerodynamic, high gearing. It’s all about efficiency. Mountain bikes are like a Jeep. They are built to be stronger, but less stiff to absorb the trail. They all have front suspension, and many have rear suspension as well. They have very wide gear ratios and big knobby tires that are run at about 30 psi, while road tires run at 120 psi.
My bike was built from the ground up for racing. I started with a Trek 8900 aluminum race frame weighing 3.2 pounds and selected each part for the precise fit and function that I wanted. For example, my saddle sits almost 5 inches higher than my handlebars to get an aerodynamic and powerful riding position. The handlebar I chose is made of high-modulus carbon fiber to save weight and damp out vibrations. My seatpost is tubular titanium that is slightly bent backward to allow flex. Not only is the titanium light, but its backward curve acts as a virtual suspension, saving my body from the abuse of the trail.
My suspension fork boasts its own unique features. Instead of using a steel coil, the fork relies on a high pressure air chamber as the main spring to save weight. The fork also has a "lockout," which closes the rebound damping circuits holding the fork in its downward position. In its lockout mode, the bike has a steeper head tube angle which makes climbing easier and sprinting more efficient. Weighing only about 22 pounds, its speed makes it well worth the price of admission.
Simon Koster