Almost every office chair has a black rotary knob underneath, which many users either don't notice or whose function is unknown. This knob controls the tilt mechanism – an important element for ergonomic seating.
This rotary knob regulates the spring tension of the tilt mechanism and determines how much resistance the backrest offers when leaning back. A correct setting can prevent back pain and significantly improve seating comfort.
What exactly does the black rotary knob do?
The black knob under your office chair is the heart of the tilt mechanism. It regulates the tension of a spring inside the chair. This spring determines how much resistance the backrest offers when you lean back.
Here's how it works:
- Turn clockwise: spring tension increases → backrest becomes firmer
- Turn counterclockwise: spring relaxes → backrest yields more easily
Why is this important?
Your body weight determines the optimal setting. A person weighing 50 kg needs less resistance than someone weighing 90 kg. Without proper adjustment, the following will happen:
- Too little resistance: They tip backwards uncontrollably.
- Too much resistance: You have to work hard to be able to sit back and relax.
- Perfect setting: You can lean back effortlessly and still have stable support.
Step-by-step: How to adjust the rotary knob correctly
1. Find the rotary knob
Feel under the front edge of the seat for a large, round button. It is usually black or grey and significantly larger than other controls.
2. Extreme testing
- Turn the knob completely to the right (clockwise) until it stops.
- Sit back – can you feel the strong resistance?
- Now turn completely to the left (counter-clockwise).
- The backrest should now give way much more easily.
3. Find the optimal point
- Start in the middle position
- Turn 2-3 turns to the right for more resistance
- Sit back and test
- Readjust step by step if necessary.
4. Golden Rule
The resistance is perfectly adjusted when you can lean back with normal effort without feeling like you are falling backward or pushing against a wall.
Common problems and solutions
I don't notice any difference when turning.
Check if the tilt mechanism is unlocked. Many office chairs have a separate lever to unlock the backrest. Some inexpensive office chairs also have a very limited range of motion.
The knob is very difficult to turn.
Relieve pressure on the backrest by leaning forward or standing up. This will make it easier to turn the knob.
Multiple turns have no effect.
That's normal. Many synchronous mechanisms require 5-8 turns for a noticeable effect. Be patient and keep turning.
The backrest doesn't move at all.
The tilt mechanism is probably locked. Look for a lever (usually on the right under the seat) that you can use to unlock the backrest.
Differences between different types of office chairs
Basic office chairs: The adjustment knob often has only a limited effect. With very inexpensive models, you'll hardly notice a difference.
High-quality office chairs: Clearly noticeable adjustment of the spring tension. Often, 3-5 turns are necessary for noticeable changes.
Premium office chairs: Some models, such as the Sihoo Doro C300, do away with the rotary knob altogether and automatically adjust the resistance to the body weight.
Conclusion
The black dial under your office chair is not a mystery, but an important ergonomic feature . It adjusts the backrest to your body weight and makes sitting for hours much more comfortable.
The most important points in brief:
- Rotary knob regulates spring force of the rocker mechanism
- Clockwise = more resistance
- Counterclockwise = less resistance
- Adjusting to body weight prevents discomfort
- Usually, several turns are needed for a noticeable effect.
Quick tip: Stand up now, find the black adjustment knob under your chair, and try it out. Turn it all the way to the right, then all the way to the left, and find your perfect setting. Your back will thank you!
