Considerations regarding suspension forks for a guy who weighs 300 lbs. must include the rider’s dexterity and level of expertise. Many professional athletes in this weight range have the ability to handle a bike with typical mountain bike suspension. On the other hand, an inexperienced 300-lb. rider with average physical ability would need suspension that provides balance and control in off-road conditions.
Suspension forks are designed to compress and extend similar to shocks absorbers on a vehicle. When you encounter a bump, the downforce of your upper body weight on the handlebars compresses the forks, providing the suspension cushion. Following a bump, the forks extend and the front of the bike returns to its original position. The combination of downforce and the compressed suspension minimizes steering control that you don’t regain until the forks extend and return the front of the bike to horizontal.
Standard dual-suspension forks operate by internal air pressure or coil-over springs. Rockshoks and STX dual-suspension forks have adjustments that allow you to regulate the tension of the front suspension. As an experienced 300-lb. rider, you might elect to set the tension for minimum compression and maximum steering control. But an inexperienced rider might encounter situations, such as a series of bumps at faster speeds, where the front end becomes unstable due to tighter suspension. In this event, reducing the tension improves cushion and provides comfort. Again, the rider must accept a compromise with regard to less compression and reduced steering control.
Another alternative, and possibly the best for heavier riders, is Cannondale Lefty's oil shock suspension. Unlike dual-suspension forks that have a shock at each fork leg, Lefty’s feature a single shock at the fork steering stem and rigid forks. With dual suspension, the bottom of both fork legs must be even so they compress the same amount. If a heavy rider leans to one side, the forks compress unevenly, affecting the rider’s control. The single oil shock and rigid fork legs eliminate this problem.
Suspension fork shocks are manufactured in a variety of sizes that allow you to select a set that’s suited to the frame geometry of your bike. Installing incompatible forks can affect the bike’s center of gravity and your steering control. Consult an expert and select the size forks that are compatible with the head angle of the steering headset. With regard to the type, a good suspension fork for a guy who weighs 300 lbs. is one that suits his physical ability and level of mountain bike expertise.