Classic FOX fork dampers explained: R, RL, RLT, RLC and X

R, RL, RLT, RLC or X? These similar-looking names describe different damper functions on classic FOX forks. This guide focuses on the 32 mm models covered in our Parts Finder, up to model year 2006.

Spring system and damper: two different things

FLOAT, TALAS and Vanilla describe the fork’s spring system. R, RL, RLT, RLC and X describe its damping features. A matching name alone is not proof that two cartridges or their individual parts are interchangeable.

R: adjustable rebound

Rebound controls how quickly the fork extends after an impact. The red adjuster lets you tune this return speed. An R damper does not provide a rider-operated lockout.

RL: rebound and lockout

RL adds a manually operated lockout. The blue lever below the red rebound knob makes the fork firmer for climbing or smooth ground. Lockout is not an absolute mechanical stop: the 2005 FOX manual describes a blow-off function for bigger impacts.

RLT: RL with an adjustable lockout threshold

RLT adds an adjustable blow-off threshold. The adjuster at the bottom of the right fork leg controls how much impact force is needed for the fork to compress while locked out. The T refers to threshold, not remote control. RLT does not have the RLC’s separate low-speed compression adjustment.

RLC: an additional low-speed compression adjustment

RLC provides rebound, lockout and a separate low-speed compression adjustment. On the classic models described here, it also has an adjustable lockout blow-off threshold.

The extra blue adjustment ring beneath the blue lockout lever is a useful identification feature. Low-speed compression refers to the speed of the suspension’s movement, not how fast the bicycle is travelling.

X: TerraLogic

The F80X and F100X use an inertia valve to control lockout automatically in response to trail input. They are not simply RL or RLT cartridges with a different knob. The 2005 manual describes rebound and bump-threshold adjustment, while noting that some original-equipment versions do not have an external bump-threshold adjuster.

Identifying a loose cartridge

Compare the full set of adjusters, the lower end, dimensions and any part numbers. A spring on the cartridge or the colour of an adjuster is not enough to identify the version. Rebound knobs also differ in diameter: our workshop stock check confirmed a larger 210-22-137 for R/X and a smaller 210-22-210 for RL/RLC/RLT. Check the exact cartridge version before ordering.

Can your fork be upgraded?

At Retro Bike Parts, we offer damper upgrades where a suitable compatible cartridge is available. Depending on the fork, an upgrade can add adjustment options and can be combined with a complete restoration.

Compatibility depends on model, year, travel and cartridge version. Matching external adjusters do not prove that complete cartridges are interchangeable. Send us your fork details and clear photos through our contact page so we can check the options before you buy.

Find parts for your fork in our Parts Finder

Reference

FOX FORX Owner’s Manual 2005, pages 9–10, plus workshop verification of the rebound adjusters. Features and parts can vary by model year and original-equipment specification.