Marzocchi part number 549258. The red lower LO-rebound knob on the 380 fork. Small, red anodised aluminium, secured by a hex socket set screw — and notorious for working itself loose during riding.
Why it gets loose
The set screw that holds the knob onto the rebound adjuster shaft is small and sits exposed at the lower leg. Vibration, mud, and repeated adjustment cycles work the screw loose over time. Once the screw backs out, the knob spins freely on the shaft and is typically lost within the next few rides.
Marzocchi specified a thread-locking compound on the set screw from factory.
If you're reinstalling or have a knob that's moving: apply a small amount of medium-strength threadlocker (e.g. Loctite 243) to the set screw before tightening. This is the correct fix.
If yours is already gone
Marzocchi 380 - such great forks and useless if it's missing a simple knob - unbelievable. Since 2018 - when fkg fox dropped all Marzocchi support shocking all loyal users and bike shops - there has been no official replacement available. All OEM inventory was destroyed. wtf.
We received enough requests for these parts – yes, we are manufacturing both, the red one and the silver one underneath (8501257 & 8501258) – that we decided to produce it ourselves.
Engineering 3D model, drawings and a STEP file have been sent to our manufacturer.
First article samples will follow.
If you need one, get in touch — or simply buy it using the shop's link below. It will be in stock soon (ETA ~May 2026).