Office chair with a gas lift
Five casters, a star base, a gas cylinder, and a back that bolts on. Twenty minutes if you do the base right.
Not what you bought? Try Gaming or racing chair · Four-leg desk or table · Nursery glider and rocking recliner
What you need
In the box already: Allen key · Hex bolts and washers · Five casters · Gas cylinder and sleeve · Base and mechanism cover
Before you open anything
- Do it on carpet or cardboard. Chair bases are heavy plastic or steel and will mark a floor.
- Keep every bolt in its labelled bag until the step that needs it. Office chairs use three or four bolt lengths that look identical.
- Leave the plastic on the seat until the end so you do not get hand oil on new fabric.
Please don't skip these
- Never try to open, cut, or puncture a gas cylinder. It is under high pressure and can injure you seriously.
- If a caster will not seat, do not stand on the base to force it. Lay it flat and press down with your palm over the socket.
The whole thing, step by step
9 steps-
Press the casters into the base
Flip the five-armed base upside down and push each caster into its socket until it clicks. They push in. There are no screws.
- Base upside down on carpet
- Line the caster stem up straight with the socket
- Push hard with the heel of your hand until it clicks
Tip. If one will not go, a single firm tap with a rubber mallet seats it instantly.Watch out. A caster that is only half in will fall out the first time you roll over a threshold. All five should look identical in height. -
Drop the gas cylinder in
Turn the base right way up and drop the gas cylinder into the center hole, narrow end up. It is a friction fit. Your weight locks it later.
- Slide the plastic sleeve onto the cylinder first if there is one
- Narrow end points up
- Drop it in, no force needed
Watch out. The plastic cover sleeve has to go on before the cylinder sits in the base. Fitting it after means pulling the chair apart. -
Bolt the seat to the mechanism
Turn the seat upside down and bolt the tilt mechanism to its underside. The lever that adjusts the height must point to the right-hand side when you sit.
- Seat upside down on your lap or the floor
- Line up all four bolt holes before starting any bolt
- Washer, then bolt, finger-tight on all four, then tighten
Tip. Start all four bolts loosely first. A mechanism bolted down at one corner will not let the others reach.Watch out. Mechanism on backwards is the single most common office chair mistake. The height lever goes on the right as you sit. -
Attach the armrests, if they are separate
Armrests bolt to the underside of the seat, often through the same area. They are handed, so there is a left and a right.
- Hold each arm in place and see which curve matches the seat
- Finger-tight both bolts, then tighten
- Check both arms end up the same height
Tip. If the arms look lopsided, you have them swapped. Swap and they will match. -
Bolt the back on
The back attaches either to a bracket on the seat or directly into the seat's rear. Hold it in place, start every bolt loosely, then tighten them all.
- Have the back at the angle the manual shows
- Start all bolts by hand before tightening any
- Tighten in a cross pattern, not one side at a time
Tip. If you are working alone, lean the back against a wall or box to hold it while you start the first bolt.Watch out. Mesh chairs often hide these bolts behind a plastic cover you have to unclip first. Look for a seam. -
Snap on the covers
The plastic shells that hide the bolts clip on last. Line up the tabs and press until they click all the way round.
- Line up every tab before pressing
- Press firmly along the whole seam
- They should sit flush with no gap
Watch out. Forcing a cover on at an angle snaps the tabs. If it resists, you are misaligned. -
Lower the seat onto the cylinder
Line the hole in the mechanism up with the top of the gas cylinder and press the seat down. Then sit on it. Your weight is what locks it together.
- Line up and press down firmly
- Sit down on it fully
- Stand up and check it has not come loose
Tip. It feels alarmingly loose until you sit on it. That is normal — a tapered friction fit. Your body weight seats it permanently. -
Tune it to your body
Height so your feet are flat and your thighs level. Tilt tension so you can lean back without falling. Lumbar support in the small of your back.
- Feet flat, knees at about a right angle
- Elbows roughly level with the desk
- Tilt tension knob under the seat: clockwise is firmer
Tip. Most people run an office chair too low and too far from the desk. Raise it, pull it in, and your shoulders will thank you. -
Roll it, rock it, tighten it
Roll it around and rock in it. Any clunk is a loose bolt. Give every bolt one last check and you are done.
- Roll over carpet and hard floor
- Rock back and sit heavily
- Final tighten on back and seat bolts
Tip. Re-check the back bolts after a week. They settle, and a loose back is what makes a chair feel cheap.
If something has gone wrong
The chair sinks down slowly when I sit on it
The gas cylinder has failed. It is not repairable but it is a cheap, universal part — almost all office chairs use the same size. Search 'office chair gas cylinder replacement' and swap it out.
The seat will not stay on the cylinder
Sit on it properly. It is a tapered friction fit that needs real weight to seat. If it still lifts off, check the cylinder is dropped fully into the base.
The back leans to one side
One side's bolts are tighter than the other, or a washer was missed. Loosen all the back bolts, hold it straight, and tighten evenly in a cross pattern.
A caster keeps falling out
It was never fully seated. Lay the base on its side, line the stem up straight, and hit it once with a rubber mallet. If the socket itself is cracked, the base needs replacing.
The height lever is on the wrong side
The mechanism is bolted on backwards. Undo the four bolts under the seat, turn it 180 degrees, re-bolt.
It rolls away on hardwood floors
Standard office casters are made for carpet. Swap in rubber or polyurethane casters — they pull out and push in, no tools, and they cost very little.
Words you will see in the manual
- gas cylinder
- The pneumatic post that raises and lowers a chair seat. Never cut or open one. When it fails the chair sinks, and it is a cheap universal replacement part.
- caster
- A chair or cart wheel that pushes into a socket. No screws. Push until it clicks, and all of them should sit at the same height.
- mechanism
- The tilt and height assembly bolted under a chair seat. The height lever goes on the right as you sit.
- washer
- A flat metal ring that goes under a bolt head. It spreads the load so the bolt does not pull through the material. Never leave one out.