Cybex Sirona Gi i-Size Review
Integrated-base rotation and rear-facing travel to 105cm
A practical review of the Cybex Sirona Gi i-Size, covering its 360° rotation, integrated ISOFIX base, rear-facing range, separately sold newborn inlay, independent ADAC result, vehicle fit and the trade-offs of a 13kg rotating seat.
The Cybex Sirona Gi i-Size is best suited to families who want a rotating seat that can remain rear-facing to 105cm without buying a separate ISOFIX base. Its integrated base, door-facing boarding position and five recline settings make it a practical permanent installation, while its 2.2 “Good” ADAC result adds useful independent evidence. The main trade-offs are its 13kg weight and the fact that babies below 61cm require the separately sold newborn inlay. Check the Cybex vehicle-compatibility tool before buying.
Published specifications
| Specification | Detail |
|---|---|
| Product | Cybex Sirona Gi i-Size with integrated base |
| Approval | UN R129/03 |
| Rear-facing range | 61–105cm; from 40cm with the Sirona Gi newborn inlay |
| Forward-facing range | 76–105cm, once the child is at least 15 months old |
| Maximum child weight | 20kg |
| Installation | Integrated ISOFIX base with load leg; no vehicle-belt installation |
| Rotation | 360° |
| Recline | Five positions in rear- and forward-facing use, including while turned towards the door |
| Headrest | 12 positions with the harness adjusting as the headrest moves |
| Harness | Integrated five-point harness |
| Dimensions | Approximately 71 x 44 x 75cm |
| Product weight | Approximately 13kg including the integrated base |
| Cover care | Fabric covers machine washable at 30°C |
| Included | Sirona Gi i-Size seat, integrated base and user guide |
| Sold separately | Newborn inlay, summer cover, cup holder, SensorSafe toddler kit and ISOFIX guides |
| Typical price | Commonly around £240–£300, depending on fabric, colour and retailer promotion |
Rotation, installation and daily use
An integrated base simplifies the buying decision
The Sirona Gi arrives with its ISOFIX base permanently integrated, so there is no separate base to add to the budget or match to the seat. The connectors and load leg remain part of the 13kg unit. This is convenient for a seat that will stay installed, but it also makes the Sirona Gi awkward to move regularly between cars.
Visual indicators help confirm that the ISOFIX connectors and load leg are engaged. The seat cannot be installed with the vehicle belt, so the intended seating position needs suitable ISOFIX anchor points and enough room for the load leg. An i-Size-marked vehicle position is the simplest match; otherwise use Cybex’s compatibility checker for the exact make, model and year.
Rotation is the everyday reason to choose it
The seat turns to face the open car door, allowing the child to be placed into the shell and harnessed before it is returned to the travel position. This should reduce twisting and reaching compared with loading a child directly into a fixed rear-facing seat. The seat can be reclined across five positions in either travel direction and while facing the door.
The 12-position headrest and linked harness adjustment remove the need to rethread the shoulder straps as the child grows. Harness loops hold the straps aside during boarding—a small feature, but one that can make repeated school-run and nursery-run loading less fiddly.
Comfort, ventilation and cleaning
All Sirona Gi versions have ventilation channels through the shell. The Plus fabric adds mesh panels and is the more breathable option, while the standard fabric is usually less expensive. This is a fabric choice rather than a different seat generation.
The covers can be machine washed at 30°C. ADAC found the seat well padded and spacious, although it also noted that removing the cover is more involved than on some alternatives. Food and grit can be vacuumed from the shell without dismantling the seat.
Rear-facing range and newborn setup
Without an additional insert, the Sirona Gi is intended for children measuring 61–105cm—roughly from three months to four years, although height and weight limits matter more than age estimates. It can remain rear-facing throughout that range, up to the 20kg maximum.
Forward-facing use is permitted from 76cm and at least 15 months, but it is optional rather than a required transition point. Families buying the Sirona Gi for its extended rear-facing capability can continue using it rear-facing until the child reaches 105cm or 20kg.
Use from 40cm requires the Sirona Gi newborn inlay, which is sold separately and is designed for babies measuring 40–60cm. The standard box contains the seat, integrated base and user guide—not the newborn inlay. This distinction matters when comparing prices with seats whose infant insert is included.
Independent ADAC result
In ADAC’s May 2024 child-seat test, the Cybex Sirona Gi i-Size received an overall score of 2.2, rated “Good”. It scored 2.1 for safety, with ADAC recording a low injury risk in both frontal and side-impact testing, alongside stable installation and good harness routing. Its weaker points were its high weight, slightly more involved child fastening and the effort required to remove the cover. This makes the result more useful than a simple award badge: it supports the seat’s safety case while also reflecting the everyday compromises of a large rotating design.
What is included and what costs extra
The purchase includes the toddler seat, integrated ISOFIX base and user guide. No additional base is needed. The newborn inlay is the only essential extra if the child is below 61cm; it remains readily available as a named Sirona G/Sirona Gi accessory.
Other optional additions include a summer cover, cup holder and SensorSafe toddler kit. These may improve comfort or add alerts, but they are not required for the seat to meet its approved specification. Check that any accessory names the Sirona Gi explicitly before buying.
What to compare it with
The Cybex Sirona G i-Size is the more logical choice for families who already own a compatible Base G from a Cloud G infant-carrier setup. It is a separate seat-and-base system, whereas the Sirona Gi has the base built in.
The Sirona T i-Size sits in Cybex’s Platinum range and uses a separate Base T or Base Z2. It supports use from 45cm with its included newborn inlay, but the complete seat-and-base setup is usually more expensive. These are parallel Cybex systems rather than older and newer versions of one product.
Families prioritising the longest possible rear-facing period should also compare fixed extended-rear-facing seats that continue beyond 105cm. They lack the Sirona Gi’s convenient rotation but may remain suitable for a taller or heavier child.
Editorial scores
Scores are editorial assessments based on the published specification, integrated-base setup, ADAC evidence, accessory requirements, pricing and suitability for different family routines. They do not represent Modern Parenting crash testing or prolonged personal use.
Who the Sirona Gi suits
Strong fit if…
Think twice if…
A well-evidenced rotating seat for families who want the base included and plan to leave it installed.
The Cybex Sirona Gi combines the convenience of 360° boarding with rear-facing use to 105cm, a 20kg limit and an integrated base. Its ADAC result is a meaningful strength, while five recline positions, linked headrest-and-harness adjustment and washable fabrics make it practical for everyday family use.
The newborn setup is less complete than the main product imagery can suggest because the inlay is sold separately. It is also heavy and ends at 105cm, so it is not the right answer for families who frequently swap cars or want the longest possible rear-facing limits. For a compatible car and a permanent installation, it is a strong all-round rotating option.
