I would sort of like to know a similar thing and how a shop determines the valving when you give them rider weight, bike weight, riding style etc and how they determine shim qty, thickness and OD? is there just a mathematical formula or do they just take a guess and think 'oh these shims should work for this rider' and its all bit of trial and error? i know how valving works but i dont know how you correlate rider weight, style and bike weight etc to a set of shims? I know Race tech has a digital valving search so i assume there is a forumla to calculate the shims just as there is when you calulate the shock springs using lever ratio, swing arm measurements and rider/bike weight and sag etc