Suspension forks are now a standard component of most mountain bikes from 100 euro bargains to 10,000 euro dream machines.  True some prefer to ride a rigid fork but for most this is a critical core component of their bike.  The range and diversity of forks is truly baffling so what makes them diferent and what should you look for in a fork?

First up what will you use it for?  Are you a cross country rider, a casual weekend warrior, a dirt jumper or do you prefer going downhill fast?  For each of these there are different forks with different performance variables and at considerably different price points too.  Also consider your riding style.  Are you an aggressive rider who looks for the jumps and thrashes their bike - do you go through a lot of parts?  Do you tend to fit-and-forget and only service something when it breaks?  If the answer to these is yes then you need a workhorse fork.  Also remember that just like a racing car needs lots of servicing and tuning, all race forks will need similar TLC to keep them race tuned.

Next up you need to know some basics.  Forks are operated by a main spring chamber.  On lighter forks this is an air piston on a heavier duty forks its usually a coil spring.  Without some form of damping the fork would operate like a pogo stick so forks feature a damping system which controls how much the fork “bobs”.  One of the best explanations of this is to think of it as the amount of time it takes for the fork to slow down when it has hit something.  Every rider has a different weight and importantly an attitude on the bike (do you lean forward on a downhill or hang back with your weight over the saddle?).  As a result you need to control the speed of how the fork deals with a bump and this is usually set with a dial.

Rebound is the reverse of this.  It controls how quickly the fork returns to its normal setting.  Not all forks come with this setting, it tends to be on more expensive race forks.

We have placed photos of forks throughout this article as examples of the type of fork we are talking about but they by no means exhaustive, these are only the tip of the ice berg.

Cross country

For the average cross country rider/racer it is all about light weight married to a 100mm fork.  80mm forks were the norm up until a year or two ago on the top of the range bikes but the technology is such now that 100mm forks as as light, indeed many forks are interchangeable between 80 and 100mm.  Look for a fork which is post-mount so that the brake caliper will screw directly onto the fork (no need for an adapter).

Another thing riders look for is a lockout - either handlebar mounted (often called remote lockout) or mounted on the top of the fork leg.  This is very handy when you want to eliminate bob on a climb.  Carbon crowns and brake arches are some of the places that this wonder material shows up but Rock Shox have now built it into their forks for added stiffness on their Reba and SID ranges.  Expect to see other manufacturers following suit.

Popular forks include the Magura Durin (reviewed here), the Rock Shox SID & Reba, the Fox F100, and the DT Swiss XR100.  Other manufacturers include Manitou and Marozocchi.  We have personal experience of the first few and they are available at various price points from a few hundred to almost a thousand euro.  Another thing to bear in mind is your weight.  If you are a heavy rider some forks may not suit you.  Top cross country forks tend to be built for fit light racers and may not suit a Clydesdale.  For example the DT Swiss XRC100 has a maximum rider weight of 95 kilos.  Most manufacturers who design like this will have a slightly heaver but stronger fork which is more suited.  DT Swiss have their XMC 100 for which is rated up too 110 kilos.  Similarly if you are a very aggressive rider fond of drops then you might want to consider this too.

Marathon

A step up from Cross country is the 120mm marathon fork.  This is made to deal with the extra pressures of a 5 hour race so has a bit more travel.

All Mountain

This is the fastest growing market with forks from 120-150mm in travel such as the Rockshox Lyrik (pictured below left) but many other manufacturers produce similar forks such as the Magura Thor.  This has a dial which allows you to vary the amount of travel the fork has from 115 to 160mm on the fly.  These forks are designed to be bombproof and should be capable of taking anything you throw at them.  As a result they are heavier than their cross country siblings.

Common features include thru axle technology which means that the wheel is locked into the fork, creating a stiffer platform which is less liable to deflection from hitting large trail obstructions.  This format comes in two thru axle sizes - 15mm and 20mm depending on the fork you buy.  Each requires a specific hub type so be sure you know which one you are getting.  Downhill forks are exclusively 20mm.  The 15mm standard is lighter.

Downhill

These forks are the pinnacle of design and are designed to take really big hits.  6-8 inches of travel is not unusual and in order to retain stiffness these forks are often what is termed “triple clamps”.  The fork legs are clamped either side of the headset.  The reason for this is to provide more precise tracking.  The wheel stays straight and true and isn’t deflected by obstacles.

Rocks Shox’s Boxxer (newly redesigned for 2009, see here) and Fox’s double World Championship winning 40’s are the two market leaders but there are plenty of other manufacturers producing quality forks.  The big drawback to this category is the price, usually in excess of 1000 euros so if you are new to downhill check out the various forums for bargain second hand forks.  There is a huge variety in weight and adjustability across the ranges.  Think carefully about what you need.  At the product launch for the new Rock Shox Boxxer fork, the managing director of Rock Shox told us that he rides the mid range Team model, not the top World Cup model as it has too much adjustability and he didn’t need it.