The Cybex Sirona S is a fancy option for keeping kids safe. It's not just good-looking; it's made with an intelligent design that catches the eye. But there's a twist in the tale. Alongside all the praise, there are quiet worries about setting it up and ensuring it stays stable, putting a bit of a cloud over its fancy image.

The Cybex Sirona S demands more engagement from its users, prompting the question: does the additional effort required to acquire this sophisticated car seat enhance its value, transforming it into a cherished essential for safeguarding children?

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ideal use

Rear-Facing Weight:

4 to 50 pounds

Rear-Facing Height Limit:

17 to 49 inches

Forward-Facing Weight:

Up to 65 pounds

Forward-Facing Height Limit:

Up to 49 inches

The Cybex Sirona S car seat is perfect for children between 4 and 65 pounds, with heights ranging from 17 to 49 inches. 

In the rear-facing mode, the infant insert should be used for weights up to 11 lbs but can work until 22 pounds. 

The rear-facing mode can continue to be used for up to 50 pounds, after which the forward-facing mode can be used until 65 pounds and 49 inches. 

Unfortunately, no booster mode is available for this car seat, meaning it is only a two-way seat.

will it fit in my car?


19 inches


24 inches


30 inches

The dimensions of the Cybex Sirona S car seat straight out of the box are 19 inches in width, 24 inches in height, and 30 inches long. 

Its dimensions are 23 inches high and 21.5 wide in the rear-facing upright position. 

When facing forward, the seat's height increases to 31 inches but reduces its length to 28.5 inches.

CYBEX Sirona S with SensorSafe, Convertible Car Seat, 360° Rotating Seat, Rear-Facing or Forward-Facing Car Seat, Easy Installation, SensorSafe Chest Clip, Instant Safety Alerts, Premium Black
Price: $349.99
(As of: 2024/07/17 6:06 pm - Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on at the time of purchase will apply to the purchase of this product.
You save: $149.96 (30%)
3 new from $347.990 used
(* = affiliate link / image source: Amazon partner program)


Do I need to use a pool noodle/rolled towel?


Easy To Install Rear-Facing?


Easy To Install Forward-Facing?


Easy To Uninstall?


Need help to install the Cybex Sirona S with LATCH? Here's a trick some parents advise:

Thread the belt's tail back through and stand behind it, pushing down firmly. This should work and won't move once tightened. Before trying this technique, the belt may be loose enough to wobble, but it shouldn't move anymore after tightening up.

I have the LATCH installation instructions for you according to the Cybex site.

How To Install The Cybex Sirona S Rear-Facing With LATCH

How To Install The Cybex Sirona S Forward-Facing With LATCH And Tether

Some parents have reported that the seat wobbles too much when locked into the base.

It's important to remember that when testing for wobbling, it should only be done on the belt path. Trying from the headrest or another part of the seat won't give an accurate indication and may result in more movement. If you experience wobbling at the top, this doesn't necessarily mean it's installed incorrectly. There shouldn't be more than 1 inch of movement when testing on the belt path.

The quality of the vehicle seat itself could also be a source of wiggling. One parent observed a lot of "loose spaces" near the back when they took out the infant car seat they used to use, which seemed to be not reversible and permanent. This made it difficult for the bottom and back of the Cybex car seat to have a good grip on the seat. Installing the Cybex S on the other unused rear seat side solved this issue with wiggling.

Here are the installation instructions using the vehicle seat belt (and tether).

How To Install The Cybex Sirona S Rear-Facing With Seat Belt

How To Install The Cybex Sirona S Forward-Facing With Seat Belt And Tether

To save time on installation, using the vehicle seatbelt is the best option as there is no weight limit on the belt compared to using LATCH installation.

Despite having numerous installation guides online, recent feedback from parents regarding installing the Cybex Sirona S with SensorSafe is overwhelmingly negative. Several users express frustration and dissatisfaction, emphasizing the difficulty and time-consuming nature of the installation process. 

Common issues include problems securing the LATCH attachments properly, challenges with the rotation function, and concerns about the seat's stability. Many parents also report that the seat remains wobbly and insecure even after repeated attempts, raising serious doubts about its safety.


Country Of Origin:

China (manufactured)

Steel-Reinforced Frame:


Five-Point Harness?


Side Impact Tested:


Approved For Airplane Use:


Easy To Buckle And Unbuckle?


The Cybex Sirona S has many safety features, but the load leg is the most notable. It's an integrated structural element at the car seat's base, reaching down to the vehicle floor and distributing crash forces away from the child by transferring crash energy to the vehicle's floor. This feature is height adjustable so that it can be perfectly tailored to your car.

The Sirona S car seat also features an anti-rebound design, which helps reduce movement towards the vehicle's rear in a crash, thus reducing crash forces for the occupant. This has a similar effect to the separately sold Anti-Rebound Bar for Britax Clicktight car seats.

The Cybex car seat also comes with the Linear Side Impact Protection (L.S.P) feature, which absorbs forces of a side impact crash and directs them into the energy-absorbing shell away from the child's neck. Placing the L.S.P system on the side of the car seat facing the door helps keep your child safer by taking the primary impact force in near-side impact situations.

By connecting the SensorSafe 4-in-1 Safety Kit to your smartphone after you have secured your child's car seat's 5-point harness system, you will be alerted to critical situations such as if the child has been left unattended in the car, if temperatures become too hot or cold, if they unbuckle their clip or if they've been seated for a prolonged period.

Despite these numerous safety features, some users note that the floor anchor is ineffective, allowing their children to move the seat quickly. 

Parents also express frustration with the belt buckle being difficult to unbuckle or too easy to undo, adding to the overall dissatisfaction with the product.

Easiest Convertible Car Seats To Install (2024)

the seat

Is The Material Breathable?


Seat Weight:

30.4 pounds

Machine Washable Cover?




No-Rethread Harness?


Easy To Remove Cover?



10 Years

Comes With A Cup Holder?

Yes, 1

Shoulder Harness Has Pads?


Recline Positions:


The Cybex Sirona S weighs 30.4 pounds, so carrying it out of the car will be awkward - as there is no handle on the seat. This is a one-piece car seat, and the base doesn’t detach, unlike the Evenflo Gold Revolve 360

Numerous reviews highlight the clunky and oversized design of the car seat, making it cumbersome for portability and travel. The seat weight is also criticized, with TSA complaints and difficulty lifting it for inspection.

To swivel, gently squeeze the recline handle, push the seat up to a completely upright position, and swivel the seat to the desired position for loading and unloading. 

If the swivel feature is stuck, it could be from your child's snacks grinding into the track when you try to rotate it - making maneuvering difficult. It can also be caused by a plastic piece along the base that frequently comes off, hindering its spinning ability.

Here’s a helpful video for unlocking a stuck seat rotation.

Finally, since the tether is needed to keep the seat firmly attached when facing forward, it will stop the seat from rotating. This means it will only turn if in a rear-facing position, just like the Graco Turn2Me.

My Final Verdict

Cybex could significantly enhance the Cybex Sirona S with SensorSafe by incorporating a rotation feature even in front-facing mode without removing the Tether strap. The 360-degree rotation is a key selling point, so its absence in forward-facing mode could be perceived as a limitation.

The installation process is a notable challenge for parents. Consistent user struggles during installation may dissuade potential buyers, leading to a situation where negative experiences overshadow any perceived benefits.

For parents searching for a car seat, exploring alternative options that offer more accessible installation, more excellent stability, and enhanced safety features might be more advisable. This recommendation is based on the shared feedback from users, where the challenges faced during installation outweigh the perceived advantages of the Cybex Sirona S with SensorSafe.

Check The Cybex Sirona S Reviews From Amazon*

What do you think?

I’d love to know your thoughts in the comments section below!



the Cybex Sirona S

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I'd love to know your thoughts in the comments section below!

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  1. The installation videos/photos all show the car seat being installed on a flat seat. But most car seats are sloped. That's a problem for rear-facing installations because the base of the Sirona S does not have a built-in foot leveler. So, a towel or pool noodle will likely have to be used for rear-facing installations.

    1. Thank you for raising this important concern Allan! You’re absolutely right about the challenge posed by sloped vehicle seats during rear-facing installations. Your thoughtful comment is greatly appreciated. If you have any further questions or observations, please don’t hesitate to share them!

  2. I want to love this car seat so much but I’m having such an issue with the wiggle. I’ve tightened it down as much as possible and it still wiggles so much at the belt path. I feel like it has something to do with how the seat base is rounded which really prevents it from sitting against the car when installing. And I’ve attempted to call Cybex’s customer service multiple times and keep getting a message that I’ve reached them after hours even though I haven’t. I did schedule an appointment to do a virtual meeting for the install, but it’s a week out which really doesn’t help me in the mean time since I need to use the car seat. And when I try to search if anyone else is having this wiggle issue or how to troubleshoot it, I can’t seem to find anything. Ugh!

    1. Hi Connie!

      Thank you so much for reaching out.

      Sometimes, the quality of the vehicle seat itself can contribute to the car seat feeling a bit wiggly. One parent mentioned noticing some “loose spaces” near the back when they removed their previous infant car seat, and this seemed to be a permanent situation. This made it challenging for the Cybex car seat to have a secure grip on the seat.

      However, when they tried installing the Cybex S on the other unused side of the rear seat, it worked like a charm! The wiggling issue was instantly resolved. So, it might be worth giving it a try in your situation as well.

      I hope this suggestion proves helpful to you. Good luck with your car seat installation.

      Kind Regards,

  3. I love this car seat but the sensor clip is very easy for a toddler to open and close. Going down the road, all I hear from my phone is clip open, then a buzz telling me it's closed, then clip open, buzz, clip open…and so on. I'm not sure that the safety features are worth the price point of this car seat if the child can easily unbuckle themselves.

    1. Hi Sarah,

      Thank you for your valuable insight. I’m sure my readers will it useful.

      It’s understandable to be concerned about the safety of your child when using a car seat with an easily opened sensor clip. It may be helpful to read reviews from other parents who have used this car seat and if they have similar problems, compare their experiences to find the best solution if there is.

      It’s worth noting that even the most secure car seat may not guarantee complete safety for your child, and it’s important to always follow the proper installation and usage instructions provided by the manufacturer.

      Kind Regards,

    2. I have the same issue with my 16 month old constantly unbuckling the sensor clip. While I love the other features of this carseat, I will be purchasing a different one and would not recommend it to others for this reason alone.

      1. I can not believe that the buckle is so easy to open. The sensor doesn’t matter if I have to keep struggling with a stubborn 24 month old baby to keep it closed as if they understand its for their own safety. They love opening it and wiggling themselves out of these things. A mire secured belt would be the least to expect from a car seat of this price point. I also have a nuna car seat, it’s excellent in keeping baby tight and sealed.

        1. Hi Iza,

          Thank you for your sharing your experience. It can be helpful for other parents who might be facing a similar situation or considering purchasing this car seat. Sharing your experience and concerns can also raise awareness among manufacturers about the importance of secure buckles in car seats, which could lead to improvements in future products.

          Kind Regards,

          1. Hi,

            Here are some points to consider:

            Safety Standards: Car seats are tested to meet specific safety standards set by regulatory authorities. Replacing parts with non-standard components could compromise the safety of the seat.

            Compatibility: The chest clip is a crucial part of the harness system for the specific car seat model. Replacing it with a different clip might not fit properly or function as intended, potentially compromising safety.

            Manufacturer Guidelines: It’s essential to consult the manual or contact the manufacturer directly about replacing the chest clip or other components.

            Warranty and Liability: Modifying a car seat, including replacing parts with non-standard components, could void the warranty and make the manufacturer or retailer not liable for any issues or accidents related to the modified seat.


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