Office chair synchronous mechanics: The gold standard for dynamic, healthy sitting
The synchronous mechanism couples the inclination of the seat and backrest in a fixed ratio, typically around 1:2 to 1:3 - so if the backrest leans back at a certain angle, the seat only follows a fraction of this movement. This principle enables dynamic sitting with constant micro-movements and is therefore considered the gold standard for ergonomic work in the office.
Hardly any other term appears as frequently in product descriptions of office chairs as "synchronous mechanism" - but what exactly is behind it and why it has a clear advantage over simpler mechanisms often remains unclear. Here is the complete technical and ergonomic classification.
How does the synchronous mechanism work in an office chair? The principle simply explained
The coupled slope ratio
With a synchronous mechanism, the seat and backrest do not move independently of one another, but in a fixed, coordinated relationship - this is common, for example 1:2 to 1:3. For example, if the backrest leans back by 30 degrees, the seat only tilts by around 10 to 15 degrees. This coordinated relationship ensures that the body remains sensibly supported in every sitting position, instead of abruptly tipping over into an unnatural position.
The “shirt-taking-off” effect (sliding effect)
With simpler mechanisms, where only the backrest moves independently, there is a noticeable sensation when leaning back Friction effect between back and backrest – The shirt or blouse is literally pushed up, while at the same time the contact with the lumbar support shifts. The synchronous mechanism largely prevents this effect, as the contact point between back and backrest hardly changes due to the coupled seat movement.
Individual weight setting
The synchronous mechanism has a synchronous mechanism so that the counter pressure of the backrest matches your own body weight when leaning back Spring force regulation. It ensures that lighter people do not feel excessive resistance and heavier people do not tip backwards without braking.
Synchronous mechanics vs. rocker mechanics vs. permanent contact: The big mechanics comparison
1. Synchronous mechanics
The ergonomic standard for everyday office life: coupled movement of seat and backrest, individually adjustable resistance, designed for 8 hours of use and more.
2. Rocker mechanism / knee rocker mechanism
Here the entire chair, including the seat, tilts around a common pivot point, usually in the back of the knee area. Simpler in design, often installed in executive chairs - well suited for short periods of leaning back, but less suitable for long-term dynamic sitting.
3. Permanent contact mechanics (PKM)
With this mechanism, the seat remains firmly in position while only the backrest moves. The back remains in constant contact with the backrest, but the lack of seat movement limits dynamic sitting compared to the synchronous mechanism.
| Mechanics type | Working principle | Maximum recommended sitting time | Ergonomic value | Suitable for whom? |
|---|---|---|---|---|
| Synchronous mechanism | Coupled inclination of seat and backrest (approx. 1:2 to 1:3) | 8+ hours | Very high | Full-time office work, permanent home office use |
| Rocker mechanism / knee rocker mechanism | Entire chair tilts around a common pivot point | Up to approx. 4-6 hours | Means | Executive chairs, reception areas, short lean-back periods |
| Permanent contact mechanics (PKM) | Fixed seat, movable backrest | Up to approx. 6 hours | Medium to good | Casual users, simple office workplaces |
Ergonomic benefits: Why the synchronous mechanism protects the spine and intervertebral discs
Promoting dynamic sitting
The synchronous mechanism enables a continuous change between different seating positions - from an upright "front wheel position" to a neutral middle position to the relaxed "rear wheel position" when leaning back. This constant change keeps the back muscles active instead of letting them relax in a rigid position.
Nutrient supply to the intervertebral discs
Intervertebral discs are formed via a passive process called Diffusion supplied with nutrients, which only works with alternating load and relief. The constant micro-movements of the synchronous mechanism actively support this exchange, which would be significantly restricted if you sat rigidly without movement.
Lumbar support in any position
Since the seat and backrest move in a coordinated manner, contact with the lumbar support is maintained even when leaning back - so the lower back support is not lost as soon as you move from an upright position.
Instructions: How to correctly set the synchronous mechanism on your office chair
Step 1 – Adjust resistance to body weight: As a test, lean back - the chair should neither tip backwards unabated nor noticeably push your back forward. Adjust the spring force regulation accordingly until a balanced counter pressure is achieved.
Step 2 – Activate freewheeling of the mechanics: Loosen any lock that may be activated so that the mechanism can move freely in everyday office life - this is the only way you can benefit from dynamic sitting.
Step 3 – Match seat depth and seat height: Adjust both values so that the knees and hips form a relaxed angle and the feet are completely on the floor - only then will the synchronous mechanism develop its full effect.
Conclusion & purchase advisor: When is an office chair with a synchronous mechanism indispensable?
For anyone who spends several hours a day at a desk, a synchronous mechanism is not optional, but the basic technical requirement for healthy, dynamic sitting. Simpler mechanisms such as the rocker mechanism or permanent contact mechanism can be sufficient for shorter sitting times or representative areas, but do not meet the demands of a busy everyday office life.
In the buerostuhl24.com range you will find high-quality, ergonomic office chairs with precisely adjustable synchronous mechanisms - for dynamic sitting that noticeably relieves the strain on the spine and intervertebral discs.