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Suspension & dropper cluster · Fault

Your fork is losing air

Quick answer

Losing air between rides usually comes from the air spring seal (the air-side leg) or the valve. Check in order: reseat and tighten the valve core, and check the pump connection — losing a few psi when you remove the pump is normal. Persistent loss, with the valve ruled out, points to an air spring service (new seals). Don't confuse it with sagging down: that's a different thing. If you're unsure of your pressure, see pressure by weight; and if it also feels harsh, check the feel first.

Before talking about a service, rule out the cheap stuff: the valve and the pump itself fool people more than you'd think.

What to check, in order

1 · Valve core — Reseat and tighten it with a valve-core tool. A loose or poorly seated core lets air escape slowly. It's the simplest cause and the first to rule out.
2 · Pump connection — Removing the pump releases the air that was in the pump and its hose: seeing a few psi drop at that moment is normal, not a fork leak. What counts is whether it loses air between rides with the pump already off.
3 · Air spring service — If, once the valve and pump are ruled out, the pressure keeps dropping between rides, the usual cause is the air spring seal. That calls for an air spring service with new seals. The call on when to do it is yours.
Anatomy of an air fork: air-side leg with the air spring and valve next to the damper cartridge leg
The leg that loses air is the air-side leg; the other side is the damper.
Common mistake: assuming there's a leak because the pressure dropped when you disconnected the pump. That drop is the pump's air, not the fork's. Re-inflate, remove the pump, and check the pressure later: only if it has dropped between rides is there a real leak.
Still losing air?

Tell us the fork model, how much the pressure drops and over how long, and we'll point you to whether it's the valve or a service. Message us on WhatsApp

FAQ

Why does it lose air between rides?

Usually the air spring seal (air-side leg) or the valve core. Start by reseating the valve core and checking the pump.

Is it normal to lose a few psi when removing the pump?

Yes, that's the air in the pump and its hose. What matters is whether it loses air between rides with the pump already off.

Is this the same as sagging down?

No. Losing air is the air spring pressure dropping at rest; sagging down is a different thing, diagnosed separately.

Related

Pressure by rider weight → Fork feels harsh → Suspension & dropper cluster →

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BikeLab-pedia · Suspension & dropper cluster / Bicycle compatibility and standards / Carlos Eduardo Ravello Joo · BikeLab Studio · Trujillo, Peru