When people shop for an ergonomic office chair, they often focus on seat height, armrests, or lumbar support. One adjustment that gets far less attention — but makes a real difference to comfort — is how the backrest height is adjusted.
Most ergonomic office chairs use one of two systems to adjust the height of the backrest:
- A ratchet mechanism
- A manual locking mechanism using a knob
They may look similar, but they behave quite differently in day-to-day use.
Why backrest height matters
Backrest height determines where the lumbar support sits on your lower back. If it’s too low or too high, the chair won’t support you properly, even if everything else is adjusted well.
A good system should:
- Allow the backrest to be positioned accurately
- Stay in place once set
- Suit how often the chair is adjusted and who is using it
Ratchet backrest adjustment
A ratchet system works by lifting or lowering the backrest until it “clicks” into position.
Pros:
- Quick and easy to adjust
- No knobs or levers to tighten
- Ideal for shared desks or hot-desking environments
Cons:
- Adjustment is in set steps, not fine increments
- Can inadvertently move out of position over time, especially with moving of the chair
- Lower-quality ratchets can wear and become less stable
Best suited to:
Shared workstations, training rooms, or environments where chairs are adjusted often by different users.
Manual (knob-based) backrest adjustment
This system uses a knob that you loosen, slide the backrest to the desired height, then tighten to lock it in place.
Pros:
- More precise positioning
- Feels firmer once set
- Less likely to move unintentionally
Cons:
- Slower to adjust
- Requires proper tightening
- Can slip over time if not maintained or if poorly designed
Best suited to:
Individual users who set their chair once and leave it in place.
Which one is better?
There is no universal “best” option — it depends on how the ergonomic office chair will be used. And possibly even more importantly, that the user takes the time to make the required adjustments.
- For single-user workstations, manual adjustment often provides better long-term stability.
- For shared or frequently adjusted chairs, ratchet systems are usually more practical.
- In both cases, build quality matters more than the mechanism itself. Don’t skimp out on a cheap chair!
Many issues people blame on “bad ergonomics” are actually the result of choosing an ergonomic office chair that doesn’t match how the workplace operates, or failing to adjust and use the equipment properly in the first place.
Why expert advice makes a difference
On paper, two chairs may look very similar. In practice, small differences in adjustment mechanisms can have a big impact on comfort, support, and durability.
An ergonomic assessment helps:
- Match the chair design to the task and environment
- Avoid common setup and selection mistakes
- Reduce trial-and-error spending on unsuitable chairs
- Ensure the chair supports the user, not just meets a checklist.
The “bottom” line
Backrest height adjustment isn’t just a technical detail — it directly affects spinal support and comfort throughout the day.
Understanding the difference between ratchet and manual systems can help you make a better choice, but getting the right ergonomic office chair for your workplace is about more than just one feature.
If you’re unsure which option suits your team or workspace, professional ergonomic advice can save time, money, and discomfort in the long run.
Contact Josh at Ergo Experts on 0409512434 or info@ergoexperts.com.au for an obligation free discussion on your ergonomic needs.
