MTB rear shock: complete maintenance and setup

Air vs coil: which shock?

Air shock: lightweight, adjustable progressiveness (tokens/spacers), adaptable to all rider sizes. The majority choice for XC, trail, and enduro. Examples: Fox Float X, RockShox Deluxe Air, Cane Creek DB Air.

Coil shock: more sensitive to small bumps, linear compression curve, simpler maintenance. Preferred in aggressive enduro and DH for sensitivity. Examples: Fox DHX2, RockShox Super Deluxe Coil, EXT Storia.

The current trend: many trail/enduro riders are going back to coil for sensitivity, accepting 200-300 g of extra weight.

Service intervals

Fox

RockShox

These are manufacturer-recommended intervals. In practice, if you ride in mud or rain, cut them in half. If you ride dry XC, you can stretch a bit.

SAG setup

The rear shock is set up like the fork (see our dedicated article). Target values:

• XC: 20-25% SAG
• Trail: 25-30%
• Enduro: 30-35%
• DH: 30-35%

For a coil shock, SAG is adjusted by changing the spring (rate in lb/in) or adjusting preload. Preload should never exceed 5 mm — if you need more, change the spring rate.

Damping adjustments

Rebound

Controls how fast the shock returns. Start with rebound at the middle of the range, then adjust:

• Too fast: the bike bounces, the rear is unstable through successive hits → close (clockwise) 2 clicks
• Too slow: the shock "packs down", it does not recover fast enough, suspension firms up through successive impacts → open (counter-clockwise) 2 clicks

Test: sit on the bike and drop your weight onto the saddle. The shock should return quickly but without launching you.

Low-speed compression (LSC)

Controls resistance to slow movements: pedal bob, weight transfer under braking, compression in berms.

• Firmer (clockwise): less bob, bike more stable when pedalling, but less sensitive to small bumps
• More open (counter-clockwise): more sensitivity, better grip, but more bob

Most trail riders set 2-4 clicks from full open.

High-speed compression (HSC)

Controls resistance to fast impacts: roots, rocks, hard hits. Only available on high-end shocks (Fox Float X2, RockShox Super Deluxe Ultimate).

• Firmer: less bottoming out, support on big impacts
• More open: more sensitivity, better absorption

Rule of thumb: start full open, and only close it if you are regularly bottoming out.

Volume spacers / tokens

Fox

Fox volume spacers are plastic rings (0.2, 0.4, 0.6, 0.8 in3) placed in the positive air chamber. The more you add, the more progressive the suspension becomes.

RockShox

RockShox Bottomless Tokens work the same way. Different shapes but same principle.

When to send for factory service?

Send your shock for service if:

• You hear a metallic clunk at bottom-out → IFP (Internal Floating Piston) needs checking
• Oil seeps from the seals → worn shaft or air can seals
• Rebound no longer responds to adjustments → worn damper piston
• Lockout no longer works → compression valve failure
• You have exceeded 200 h without service → degraded oil, reduced performance

Average cost: 80-150 EUR for a full service at Fox or RockShox. Turnaround: 1-3 weeks.

Maintenance checklist between services

• After every muddy ride: clean the shaft with a damp cloth
• Every 10 rides: apply a few drops of suspension oil (Fox Gold, RockShox Maxima) on the shaft seals
• Monthly: check air pressure (it can drop 5-10 PSI per month)
• Check shock bushings (DU bushings): if play appears, replace them before they damage the frame eyelets

Need the exact service interval or recommended spring rate for your shock? L'Atelier finds this info in the manufacturer's technical documentation.