When looking into mountain bikes, there are many different factors that should strike you when you approach the possible investment. Primary among them should be: for what purpose am I looking at this bike? Is it to travel around my local neighborhood, potentially for a novice non-paved nature excursion, or to compete on an international level for a downhill racing. Obviously the differences between these two comprise the large spectrum of bikes that you could potentially invest in. However, one small portion of the bike you might not have though of looking into is the different mountain bike forks.
The discussion on mountain bike forks is synonymous with the suspension system found in a bike. The forks can be made of different composite materials from aluminum on the cheaper end to a carbon composite on the multi-thousand dollar end of the cost spectrum, but the styles of structure usually have little variation. There is one exception to this rule, but it will be discussed in the later sections on fork variations.
The major difference in mountain bike forks comes from the difference in suspension. There are three major kinds of suspension that are to be found in mountain bikes in general: front, rear, and full suspension. The front suspension if fairly standard on most mountain bikes and usually is comprised of two air or spring concussion dampeners which are measured in mm of impact resistance. This measurement has varied from 90mm at the beginning of its introduction to extreme downhill impact resistance of 210 or 230 mm at the competitive end of hard impacts. Regardless of the type, the front suspension is typical and normal on most frontal mountain bikes forks.
In general, the suspension can be tuned based on the rider, which is known as tuning for sag. Sag is the weight that the rider places on the bike without any impacts on the suspension system. This is one of the technical terms that will be addressed in this article.
The rear suspension is where the bulk of the differentiation comes from. The first differentiation is between the presence and absence of a rear suspension system. This difference is known as hard and soft tail suspension system. Hard tail means there is no suspension system in the back, whereas soft tail means there is an impact dampening system on the rear mountain bike forks.
Within the soft tail design there has been a lot of innovation in the last ten or twelve years. In 1997 Trek came out with the Y style rear suspension system. This system put a large coil shock under the seat of the rider and disconnected it from the rear axle. It was connected to the frame of the bike which then connected to the front and rear axles, but the impact was mitigated by the shock and the large frame structure. This was the first major innovation in soft tail technology that started a lot of research and development between international competitors for the off road extreme mountain biking sport that correlated with a spike in interest in the sport.
From here mountain bike forks have seen increased attention in the rear suspension that has culminated in the term of full suspension with the brands that think they have solved the suspension dilemma found in extreme or even moderate off road mountain biking. There are numerous forms of rear suspension each of which is associated with a patent for a certain company who invented it, but the largest are these systems: single soft tail, single pivot, unified rear triangle, four bar suspensions, Horst link, virtual pivot point, Dave Weagle’s link, split pivot, Monolink, and Equilink. All of these forms of pivots and link are jargon used to denote different numbers and points of pivots where a shock can be place to reduce impact. The most modern and innovative forms of these have reduced the rear shock’s tendency to dampen the downward pedaling force of the driver. Some modern systems have incorporated a lockout system which makes the bike hard tail at the flick of a switch, although a blowout/overdrive balancer must be placed which completes mountain bike forks.