The Difference Between Front and Rear Suspension Systems in Mountain Bikes.

mountain bike suspensionThe sport of mountain biking can be hard on both equipment and the body of the rider. To make a day on the trail easier on a mountain biker, mountain bike companies have spent years perfecting suspension systems that reduce the amount of abuse the rider experiences during a trail ride.

Aside from rider comfort, a mountain bike’s suspension system makes trail riding safer. The suspension system absorbs bumps and this increases the amount of tire to ground contact, which allows the rider to have better control of the mountain bike.

When it comes to mountain bike suspension systems, the most important factor to keep in mind is travel. The travel of the suspension system is important and is directly related to the terrain and type of trails the mountain bike is most often likely to see. The greater the amount of travel in the suspension system, the larger amount of shock the suspension will be able to absorb.

Front Suspension: Overview

The term hardtail came about with the addition of a suspension system to the front of a mountain bike. A suspension fork is comprised of a spring and a dampener. The combination of these two components effectively reduces bumps and vibrations caused by trail hazards, greatly enhancing the rider’s control of the bike.

There are a few different variations of the suspension fork, but all have different combinations of springs and dampers. The spring in a front suspension system does not necessarily have to be an actual spring. Many types of suspension forks utilize a steel spring and less expensive front suspension systems replace the steel spring with polymer cylinders. If the spring was the only component of the suspension system, the suspension could bottom out when a large bump is encounter and the front fork would recoil and cause the front end of the bike to bounce repeatedly after a bump was hit.

The damping system is used to eliminate the possibility of the suspension system bottoming out when a large obstacle is hit with the front tire and also reduces the bounce associated with the spring. Most dampening systems are fluid filled and contain valves that allow the fluid to pass and enter the damper when needed. This greatly enhances the action of the suspension system and depending on the manufacture the damper can be adjusted for the riders riding level and the conditions of the trail they intend to ride.

Rear Suspension Systems: Overview

Early full suspension mountain bikes where shunned by many enthusiasts due to the weight added by the rear suspension system and pedal bob. Pedal bob was a problem on early rear suspension systems and is caused by a weaker suspension system. When the rider pedals, the suspension would give under the torque of the chain and the bike would bob slightly up and down. Another issue caused by pedal bob is pedal inefficiency. When the rider pedals a lot of the momentum is lost as the suspension would absorb not only bumps, but also part of the pedal stroke.

Todays full suspension mountain bikes have changed all that, newer more modern materials and better suspension system designs have made the weight difference between a full suspension bike and a hardtail nearly unnoticeable and pedal bob has been nearly completely eliminated. This has greatly improved the handling qualities, weight distribution, and efficiency of full suspension mountain bikes.

Unlike the front suspension forks seen on mountain bikes, rear suspension systems are available in a wide variety of types and styles. Some rear suspension systems resemble a “normal” hardtail bike and others look fit to be part of a motorcycle suspension.

Single Pivot Rear Suspension

The single pivot suspension system is common and is one of the simplest types of rear suspensions used on mountain bikes. A single pivot system, being relatively simple, is easy to maintain due to fewer parts that needed to be cleaned and oiled. Although simple, this type of rear suspension is highly effective and many manufactures offer upgraded shocks that allow the rider to customize the ride of their bike.

Besides the single pivots simplicity, another factor that makes this type of rear suspension desirable is its strength. This makes a single pivot rear suspension a great choice for mountain bikers that ride hard or novice riders that need a low maintenance suspension that is more durable and forgiving.

Four Bar Linkage Rear Suspension

A four bar linkage suspension system allows the suspensions pivot point to move in an arc rather than a straight line. This feature has both advantages and disadvantages over other types of rear suspension systems. Since the movement of the pivot is an arc, shocks are absorbed over a greater stroke. This increases the amount of adjustment that a rider has to tailor the suspension for a specific ride and also increases the life of the shock absorber. The main disadvantage of this type of suspension system is high maintenance. With the increased amount of components a four bar linkage suspension has a lot of bearings and other parts that need to be cleaned and oiled on a regular basis. If proper maintenance is not performed, problems can arise while out on the trail and nothing can be more frustrating than equipment failure during a ride.

A properly designed four bar linkage suspension will be ruggedly constructed and will have the shock absorber mounted to the front side of the seat post riser. When the shock is mounted behind the seat riser, facing the rear wheel, a lot of strength is removed from the system and mounting components can fail during a hard ride.

Parallel Beam Rear Suspension

Parallel Beam suspension systems were once toted as the greatest suspension system of all time. That can be true if the twin beams are exactly parallel and the suspension is set-up with a lot of travel. Unfortunately during a day of mountain biking, the suspension can twist under certain loads and result in pedal inefficiency, bob, and brake jack. This is not to say that the parallel beam suspension is all bad, if the travel is set correctly and the trails are not that rugged, this type of suspension can outshine other types of rear suspensions.

The one drawback that is seen in any complex suspension system is maintenance. Any complex suspension system will utilize bearings at the pivot points of the suspension and all bearings will require routine cleaning and lubrication.

Conclusion

Investing in a full suspension mountain bike is well worth the money for any rider that is devoted to the sport. The few added components that need to be maintained is a small price to pay for a comfortable and safe day on the trail.