Cybex Sirona Gi i-Size Review 2026
Integrated base and 360° rotation — is 105cm rear-facing range enough for your family?
A buyer-fit review of the current Sirona Gi, including the integrated ISOFIX base, 61–105cm range, separate newborn inlay, independent ADAC result and the situations where a longer-range ERF seat makes more sense.
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Vehicle compatibility comes before the feature list. The Sirona Gi uses integrated ISOFIX connectors and a load leg. Check the exact seating position in the vehicle manual and CYBEX compatibility information before buying.
A strong rotating 105cm seat when it can stay installed
The Sirona Gi is at its best as a permanent, integrated-base seat in one compatible car.
The published specifications that actually change the buying decision
This remains a current CYBEX Gold seat; the integrated base is part of the product rather than an additional purchase.
The normal approved range starts at 61cm. CYBEX sells a separate newborn inlay that extends use down to 40cm and is removed once the baby is taller than 60cm. Forward-facing use is approved from 76cm only once the child is at least 15 months old; that is a permission point, not a deadline to turn the seat.
The seat has a 12-position headrest, linked harness adjustment, five recline positions and all-round ventilation. Plus fabrics add mesh panels; they do not change the underlying approval range.
Rotation is the practical reason to choose this type of seat
The integrated base simplifies the purchase but makes the whole unit something you will probably want to leave in place.
The Sirona Gi turns towards the open car door for loading and harnessing, then rotates back into the approved travel position. That can make the repeated lift-and-twist movement of a fixed rear-facing seat noticeably easier, particularly in higher cars or tight parking spaces.
The trade-off is obvious once you look at the 13kg product weight. There is no separate base to leave behind when moving the seat: the ISOFIX hardware and load leg are part of the same unit. If one child seat is regularly shared between two cars, a lighter or modular setup may be more practical.
Its useful rear-facing window is 61–105cm — or 40cm with the extra inlay
This is extended relative to the legal minimum, but it is not one of the longest-range 125cm rear-facing seats.
Used rear-facing, the Sirona Gi covers its full main 61–105cm range up to 20kg. With the separate newborn inlay it can start at 40cm. CYBEX permits forward-facing from 76cm and over 15 months, but recommends rear-facing for longer.
If your main priority is keeping a taller/heavier child rear-facing beyond 105cm, compare dedicated extended-rear-facing seats such as the current 125cm options in our ERF guide. You give up easy 360° rotation, but gain a longer approved rear-facing window.
ADAC rated the Sirona Gi “Good” in its 2024 test
Approval tells you the seat passed the regulation; independent testing adds a second layer of information.
ADAC’s May 2024 assessment gave the Sirona Gi i-Size an overall result of 2.2 (“Good”), with a 2.1 safety result and low reported injury risk in both frontal and side-impact testing. ADAC also noted stable installation and good belt/harness routing.
The same test helps expose the compromises: the seat is heavy, fastening the child is a little more involved than in some alternatives, and removing the cover is not especially simple. That is more useful than turning the ADAC result into another Modern Parenting score.
Three different reasons to choose something else
Choose the alternative according to what the Sirona Gi does not optimise.
Frequently asked questions
The points worth checking before you act.
Yes. The base, ISOFIX connectors and load leg are integrated into the seat.
No. The separately sold Sirona Gi newborn inlay extends approved use from 61cm down to 40cm.
Until 105cm or 20kg, whichever approved limit is reached first.
No. Forward-facing becomes permitted only from at least 15 months and 76cm. The seat can remain rear-facing through its approved range.
No. Check the exact vehicle seating position against CYBEX compatibility information and the vehicle handbook, including load-leg requirements.
Yes. CYBEX continues to list the Sirona Gi i-Size in its current UK toddler-seat range.
Related Modern Parenting guides
Current CYBEX specifications and independent test information checked 18 August 2026. Always follow the child-seat and vehicle instructions and confirm compatibility for the exact seating position. Affiliate links: some links may earn us a small commission. Full disclosure →