# Office chair keeps sinking: causes and fixes Source: https://chairandposture.co.uk/blog/office-chair-keeps-sinking Published: 2026-10-12 Publisher: Chair and Posture **In short:** A chair that sinks on its own almost always has a worn gas lift cylinder: the internal seal lets gas pass, so the seat drops under your weight. First rule out a lever that is stuck in the raised position. A hose clamp or a cut length of pipe around the cylinder can hold the seat at one height as a temporary fix, but the proper repair is to replace the gas lift, which is a standard part on most chairs. Few things are more irritating than a chair that slowly lowers you towards the floor through the morning. It happens to office and gaming chairs alike, usually after a few years of use, and it is nearly always the gas lift. The good news is that the gas lift is a standard part, so the chair can usually be saved. This guide explains why chairs sink, how to rule out simpler causes, two temporary fixes, and when to replace the cylinder. ## Why chairs sink Seat height on an office chair is controlled by a gas lift: a sealed cylinder of pressurised nitrogen with a piston inside. When you pull the lever, it presses a release pin on top of the cylinder, opening a valve. Your weight pushes the seat down; when you stand, the gas pushes it up. Release the lever and the valve closes, locking the height. Over time the seals inside the cylinder wear. Gas slowly leaks past the piston, so the seat creeps down under your weight even with the valve closed. Heavier users and chairs used all day wear seals faster, and cheap cylinders tend to fail sooner. A class 4 gas lift is the heavier-duty grade; many chairs in our guides list class 4. ## Rule out a stuck lever first Before blaming the cylinder, check the lever. If the lever or its cable is stuck slightly raised, the release pin stays pressed and the seat drops whenever you sit. 1. Turn the chair over or tilt it so you can see under the seat. 2. Watch the lever as you move it: it should spring back fully when released. 3. Check the lever is not catching on a cushion, cable tie or the mechanism housing. 4. Look at the top of the cylinder where the lever meets the release pin; nothing should rest on the pin when the lever is released. 5. If an adjustment screw or cable is fitted, check it is not holding the pin down. ## Temporary fixes: hose clamp or pipe If the cylinder is worn, you can stop the sinking by preventing the cylinder from sliding down. These methods fix the seat at one height, so set it where you want first. The hose clamp method uses a metal hose clip tightened around the exposed chrome part of the cylinder, just below the outer tube. Raise the seat to your height, slide back the plastic cover over the cylinder, fit the clip and tighten it firmly. Some people wrap a strip of rubber under the clip for grip. The pipe method uses a length of plastic pipe, such as waste pipe, cut lengthways so it clips round the exposed cylinder, cut to the length that holds the seat at your height. Both are workarounds. You lose height adjustment, and the clamp can slip if not tightened properly. Use them while you wait for a replacement part. Note: Never cut, drill, heat or try to open a gas lift cylinder. It holds gas under pressure and can cause injury. ## When to replace the gas lift If the seat sinks with the lever working normally, the cylinder needs replacing. Most office chairs use a standard tapered fitting, so replacement cylinders are widely sold. Measure the old cylinder's length and check the class before ordering. Our [gas cylinder replacement guide](https://chairandposture.co.uk/blog/replace-office-chair-gas-cylinder) covers removal, measuring and fitting. Check your warranty first. Some makers include gas lifts specifically; Melokea, for example, states free replacement gas lifts within its 5-year warranty, and ProtoArc offers free replacement parts within its warranty period. [Heavy-duty chairs with class 4 lifts](https://chairandposture.co.uk/best/best-office-chairs-for-heavy-people) ## Gaming chairs that keep lowering Gaming chairs use the same gas lifts, so the same fixes apply. Some gaming chairs have a longer cylinder cover or a base design that hides the cylinder; you may need to slide the cover up or remove it to fit a clamp. If the chair is still under warranty, contact the maker before modifying it. ## Frequently asked questions **Why does my office chair keep sinking?** The gas lift seal is worn, letting gas leak past the piston. Occasionally a stuck lever causes it. **Can I refill a gas lift?** No. Cylinders are sealed. Replace the cylinder instead. **Is the hose clamp trick safe?** It is a common temporary fix if the clamp is tight and fitted to the exposed cylinder only. Replace the cylinder as soon as you can. **Why does my gaming chair keep lowering?** For the same reason: a worn gas lift. The fixes are the same as for office chairs. ## Buying guides on this topic - https://chairandposture.co.uk/best/best-office-chairs-for-heavy-people - https://chairandposture.co.uk/best/best-ergonomic-office-chairs - https://chairandposture.co.uk/best/best-gaming-chair-under-400 ## Sources - [HSE: Working safely with display screen equipment](https://www.hse.gov.uk/msd/dse/)