Suspension school · Damping Adjustments

HSR and LSR on Four-Way Dampers

Who actually needs separate rebound circuits, and the order to set them in

Most dampers give you one rebound dial. Four-way units, such as the Fox GRIP X2 fork damper, the Fox Float X2 shock and the Cane Creek Double Barrel family, split rebound into low-speed (LSR) and high-speed (HSR) circuits, mirroring the compression side. The GRIP X2 offers 16 clicks of LSR and 8 of HSR, alongside its 16 of LSC and 8 of HSC.

Low-speed rebound governs slow extension: the bike recovering from sag, rising back to height between corners, settling after braking. It is the rebound you feel in every car park test and the figure manufacturer setup tables lead with. When anyone talks about rebound without qualification, they mean this.

High-speed rebound governs fast extension, which mostly happens when the shaft returns from deep in the travel, where spring force is at its highest, or when the wheel suddenly unloads, such as leaving the lip of a jump or dropping off the back of a square edge. HSR decides whether that stored energy comes back as a controlled surge or a kick.

Who Actually Needs to Touch HSR

Honest answer: fewer riders than the marketing suggests. If you run moderate pressures and rarely use the last quarter of your travel, the energy stored deep in the spring stays modest and a sensible LSR setting handles everything. Setting HSR to the manufacturer baseline and leaving it there is a perfectly good outcome, not a failure of sophistication.

• Heavier riders and high spring pressures. The force deep in a firm spring is enormous, and without HSR damping the return from a deep hit arrives as a buck that no reasonable LSR setting can control.
• Riders regularly deep in the travel: aggressive descending, drops, flat landings, bike park laps.
• Jump-heavy riding where the rear kicks off lips even though car park rebound feels right.
• eMTB riders land in the first category more often than they expect, because heavier bikes run higher shock pressures for the same rider.

The Compromise It Ends

The reason separate circuits exist: with a single rebound dial, a heavy or hard-charging rider must slow everything down to control deep-travel returns, which leaves the top of the stroke sluggish and short on grip. Splitting the circuits lets the top of the travel stay lively (LSR relatively open) while the bottom stays controlled (HSR relatively closed). If you have ever felt forced to choose between a calm bike on big hits and a grippy bike on chatter, this is the adjustment that ends the choice.

Order of Operations

• Set LSR first, using the kerb roll test and the manufacturer's weight or pressure table. Fox publishes weight-keyed rebound settings for the GRIP X2 alongside fixed compression baselines of HSC 5 and LSC 10 from closed.
• Set compression next, low-speed then high-speed, on familiar trail.
• Set HSR last, and only on terrain that genuinely uses deep travel. It is meaningless on mellow trails.
• If you change spring pressure, revisit LSR before even thinking about HSR.

Reading HSR on the Trail

• Rear kicks or bucks off jump lips, drops and sharp compressions, while ordinary rebound behaviour feels fine: add HSR damping, one or two clicks towards closed.
• Suspension packs and rides low only through repeated big hits, while shallow chatter recovers fine: open HSR one or two clicks.
• Whole-bike pogo or nervousness on ordinary terrain: that is LSR, not HSR. Go back a step.

A caution from experience: most suspected HSR problems turn out to be LSR or spring rate problems wearing a disguise. HSR shifts the character of the bike in a narrow band of situations. If a change on the fourth dial seems to be transforming the whole bike, something earlier in the chain is probably wrong.