Originally Posted by
Andeh
What's the difference between a progressive and linear *damper* (specifically rebound) tune? I ask because of the current line of RS shocks, the retail versions all have light compression, light rebound tunes. But several of the OEM tunes (Specialized, Santa Cruz) spec progressive rebound tunes.
I figure it means one of these 2 things:
a) the rebound shaft speed starts slow (for small shaft speeds) but ramps up in a curve shape for faster shaft speeds.
b) the adjuster knob starts out with smaller (compared to linear tune) rebound speeds, but the rate increases non-linearly the more clicks you open it. i.e. the difference between click 6-7 is much less than between 14-15.
Is it either of these, or something else entirely?
I have noticed (from using a data acquisition system) that for shocks both with linear and progressive rebound tunes, the rebound velocities as a function of travel are non-linear. The scatter plot graph for shock rebound looks roughly linear up until maybe 30-45% of travel, then the slope dramatically reduces. The fork rebound plot usually looks linear throughout travel. I see this across coil and air shocks, and various brands (Fox, RS, EXT). I assume the rebound shim stack is tuned in such a way so that on bigger compressions, the shock rebound speed is less so that the rider doesn't get pitched forward.