Most forks require straightening when they reach us. Motorbike forks tend to develop a less than linear profile as a result of constant use, ie heavy braking and flexing. Mostly this is barely noticable, but any degree of curviture will effect the seal performance and accelerate seal damage leading to oil loss.
Variation: Whilst many forks, especially newer forks, do not have any degree of bend in them, many forks can typically have between 1-5mm variance between the centre and the ends. Some forks demonstrate far greater degrees of curvature and are even visibly bent to the eye.
Creasing: We can straighten almost any bend, but once the fork has developed a crease there is little that we can do because a crease represents a far greater degree of structural compromise.
The Press: A hydraulic press is used to straighten the forks. We can exert as much as 50 tons of force and can realign a stanchion to within 40µm.