What does a bypass shock do?

Answer:

While the explanation can be more complicated we’ll keep this one simple. Bypass shocks divert oil thru passages External to the normal valving shims by running extremely stiff valving. Once the oil is forced thru the external tubes/passages it is metered by a check valve with an adjustable set screw. This allows for valving adjustments without disassembly, however, the main advantage is multi-stage damping. Why? Because when you run more than one spring rate, one damping rate will not control both rates effectively.