Preload, rebound and compression, these are the terms you have come across to when reading your fork’s service manual. We will explain you in this article what effects these adjustments have and how you should set them correctly. Basically, a suspension fork offers best performance when it is tuned according to your weight but also to the track you are going to follow.
As damping is a dynamic process control its set-up has to be rigorously performed so that you enjoy its performance at the highest level.
This setting is available for coil suspension fork, and its purpose is to stiffen the coil, according to your weight. So, if you weigh more, you will have to turn the preload knob towards PLUS. This increases coil’s stiffness and fork will absorb the shocks better. If you weight less, then you will have to turn the knob towards MINUS.
Sag – negative travel
Sag refers to the fork’s travel as you get on the bike. Do it and you’ll notice that the fork compresses. It is important that travel in this case is no more than 20% of the fork’s total travel. This means that for a 100 mm fork, sag represents 20 mm.
Sag can be found on air cartridge fork, and you can set it by pumping or extracting air from the fork with the help of a special pump. Some forks have a Sag indicator, either marked on the stanchion either through a rubber ring. If your fork has neither an indicator nor a ring, attach a zip tie, right at the bottom of stanchion, next to the seal and observe/measure its negative travel.
This indicates the speed at which the fork extends back after hitting a bump. Rebound adjusters may be placed at the bottom of the right fork leg, or top of it, depending on the fork. If rebound is set at its minimum, the fork will decompress very quickly and the wheels will lose their contact with the ground. On a track with a lot of bumps (roots, stones), you will only lose time as you will have to fight to maintain control of the bike.
Should you use rebound at its high limit, the fork will be too sluggish, failing to absorb all the bumps on the track. You could notice this if you try to descent a set of stairs, you will simply lack your once usual damping travel.
Push down the handlebars using all your weight until the fork compresses at its maximum. Now, quickly remove hands from bars, observing the front wheel, as the fork comes back. If the front wheel does not bounce from the ground, then rebound is correctly set. If the fork extends to slow, add more rebound.
As the name suggests, compression refers to the speed at which the fork compresses. This setting can usually be found on expensive fork at it should be used only if when braking or jumping, the travel of the fork is too long. Usually the compression must be set to its open position.
This command renders the fork rigid, temporary disabling its travel. According to the type of fork, a lock out can block the fork completely or just partially, and some expensive force benefit even from a Lock-Out force setting, allowing the rider to adjust the rigidity of the fork when the Lock-Out lever is actuated.
If you are a beginner you might forget the Lock Out command blocked while riding on a bumpy terrain, therefore is preferable that the Lock Out force is smaller, still allowing a travel of 1-2 mm. Riding on a bumpy track with a fork having its Lock Out function actuated, may, to put it simply, destroy it.
This is a preliminary setting, to be actuated through a valve, placed on the right or the left leg of the fork, responsible for extending or reducing travel. A short travel is useful for climbs, while extended travel is suitable for downhills. However, not all forks feature this option.
In this article we have used the following forks:
Fox 32 Float (grey), Rock Shox Recon (white, for Travel adjust), Suntour XCM (white, for preload and Lock-Out), Rock Shox Lyrik (black, for Sag).