Tell me what you do with your bike and I’ll tell you which you need
Suspension forks on mountain bikes are one of the components that have developed the most in recent times, not only technologically, but also in the evolution of their ranges, their segmentation and orientation to their different uses. Today there are more types of suspension forks than ever before.
For this reason, it is logical that if you are not the most experienced of users, you may have doubts when deciding which fork to fit on your new bike or to upgrade it with a new front suspension.
The two most important aspects to look at in order to choose the most suitable for your needs are the travel and the diameter of the bars, both are definitive to understand what performance the fork is going to offer you or dictate what type of user it is for, and they are also closely linked to each other. We tell you how to better understand and interpret them when faced with the dilemma of choosing which fork is best for you.
Before analysing the different types of forks, we would like to explain the two aspects by which they can be classified.
Firstly, the travel. This refers to the sag of the fork when it is compressed. This sag of the bar inside the fork leg is usually measured in millimetres and is known as fork travel. Currently, the most common strokes range from 100 to 200 mm, and can also be 120, 130, 140, 150, 160, 170 or 180 mm, as a rule.
The other important concept when evaluating a fork is the diameter of its bars. This diameter or thickness of the bars, which is also measured in millimetres, is important, as it conditions or is one of the main factors responsible for the structural rigidity of the fork, keeping it more or less firm against the torsion and forces that occur on the bike and the front wheel, especially when riding.
Currently, we can say that the diameters of the majority of forks marketed for sports use in mountain biking range from 32 to 40 mm.
Forks from 100 to 120 mm and diameters of 32 and 34 mm
Forks offering 100- or 120-mm travel are intended for XCO use, from a competition point of view, or for rides or routes where the more physical and technically easier parts predominate. They are the forks with the least travel on the mountain bike market and therefore the lightest but also with the least absorption. For this reason, they are designed for XCO competition or sporting use in areas that are not too complicated. Within this category there is a trend towards an increasingly widespread use of the 120 mm option on the higher end models, although 100 mm forks can still be found.
In order to keep your bike’s geometry balanced and if you are considering purchasing or upgrading your bike with a new fork, you should be aware that these 100- or 120-mm models must be fitted to bikes with a rigid frame, i.e., without rear suspension, or with rear suspension but with a maximum travel of 120 mm.
These shorter travel forks have bar diameters ranging from 32 to 34 mm, the most common being 32 mm for 100 mm travel forks and 34 mm diameter for 120 mm travel forks.
The 100 mm travel and 32 mm diameter models can still make sense for girls with low weight, who will not need as much suspension stiffness, or for bikers who do not ride very technical sections.
For XCO riders who race, ride technical courses or are heavy, the 120 mm travel and 34 mm bar diameter option is much more suitable.
Forks from 130 to 160 mm and diameters of 34 or 36 mm
Following in ascending order, we find ourselves in a group of forks that we can include in travels between 130 and 160 mm. These are the models intended for so-called trail or all-mountain bikes. Full suspension bikes that normally provide similar travel at the rear of the frame thanks to the work of the shock absorber.
They are forks that stand out for a good balance between absorption capacity, they really allow to face with guarantees almost any technical difficulty, but due to their weight and height, they are still not the ones that penalise the most in ascents and in the moments in which the cyclist, for example, stands up to pedal. Let’s say that these forks are intended for bikes and users who use their bikes for routes where there is an important pedalling component, but who attach special importance to descents and tackle descents with intensity and speed.
The most common bar diameters for these forks are between 34 and 36 mm, according to the type of use for which they are intended. Obviously, the most coherent thing to do, and this is the case, is for the 120 or 130 mm to offer 34 mm while the longer travel 160 mm bars offer bar diameters of mainly 35 or even 36 mm.
Forks 170 to 190 mm and fork diameters 36 or 38 mm
In this range of travel, we find suspension forks intended for enduro or Bike Park use.
They are suspension forks with an outstanding absorption capacity, with travels approaching 200 mm that allow them to tackle very technical sections, such as jumps of a certain size or to absorb large obstacles. These forks provide great stability and control of the bicycle in the most complicated descents, although in exchange and due to their long travel and greater height than the average forks on the market, they raise the front area of the bicycle quite a lot as well as having a soft feel that can penalise in the pedalling sections.
These forks should always be used on oversprung bikes with similar rear travel, generally 160 to 190 mm, to avoid an imbalance in the geometry and behaviour of the bike between the front and rear suspension.
Its most suitable use is for enduro, with routes in which the biker does not have any desire for performance or performance, it is simply a formality to be able to reach the start of the descent. It is in this terrain that a fork of this travel is designed to provide maximum performance.
The same applies to Bike Park use. In this case, ski lifts are usually used to perform the lifts, so that the possible suspension penalty is irrelevant or non-existent on climbs, but they do provide absorption, control and stability on technical descents.
In this segment of enduro forks, the most common diameters are 36 or even 38 mm, the latter being reserved for 180 or even 190 mm models, forks that obviously require a high degree of stiffness.
Forks with 200 mm or more travel, and fork diameters from 35 to 40 mm
Although their presence on the market is very limited, as they are oriented to a very specific use, we find forks with a travel of 200 mm or more. These are suspension forks specifically for downhill bikes and competitions. This is the context in which absorption, control and stability and more rigidity of the front end of the bike are most needed. This is the type of use where the most difficult descents are ridden at the highest speed. These forks therefore require a special structure, a double upper plate that considerably increases rigidity compared to forks with less travel.
Suspension forks of 200 mm or more travel are almost exclusively for downhill bikes, models that are not intended or designed for pedalling on the flat or uphill, where they are extremely heavy and with a geometry that makes it difficult to advance pedalling with weights that are set back and a steering angle that is very far forward of the bike. Although there is no written rule, it is therefore not a good idea to mount these forks on bikes whose frames have less than 180 mm of travel.
Bar diameters range from 35 to 40 mm. It will depend on the model, but you should choose the larger diameter options if you are a heavy biker, use the bike on very technical and radical descents or with big jumps. You may not need as much travel if you weigh less and the routes are somewhat less technical.
There is currently only one manufacturer on the market that offers forks with exclusive and patented technology that allows for a single-arm suspension, unlike the rest of the forks on the market, which are made up of two arms or cylinders. This manufacturer is Cannondale, famous for its bikes, but also for its Lefty forks (they have only one arm, on the left). The advantage of this particular system is that it offers greater rigidity, as it has a larger diameter bar-bottle assembly, a solid bar-wheel axle assembly and greater sensitivity in feel as it incorporates needle bearings, which are softer and more sensitive than conventional forks.
The Lefty single-arm fork range currently includes travels from 100 to 120 mm, and in all cases, for bikes and XCO use, for rigid (without suspension) double suspension frames with 100- or 120-mm travel from any manufacturer, as the Lefty fork is compatible with any frame on the market.