The Britax Marathon (model G4.1) is a top-ranked seat in our Convertible Car Seat Review. It managed a higher than average score in every metric including crash test scores and ease of installation and use. This seat is a soft, comfortable seat that is easy for parents to install and use. It is hard to find anything wrong with this lovely product that also has the easiest to use non-rethread harness height adjustment and ten height positions for maximum adjustability and best fit for children of all sizes. This seat shines in comparison to the competition and is a standout no matter what may be important to you.
REASONS TO BUY
Good crash test results
Easy installation
Nice features
REASONS TO AVOID
Hidden belt pathway that is harder to use
Update — July 2018
The Marathon has been discontinued. Britax is in the process of rolling out a new line called Essentials and it includes a very similar convertible car seat to the Marathon called the Britax Allegiance (which is less expensive). This may be a good choice for parents who want but can't find a Marathon. they also have the Britax Emblem which is similar as well and also less expensive.
Our Analysis and Test Results
We tested the Britax Marathon model G4.1, which first became available in Oct 2014 when it replaced the G4. The Marathon has since been retired.
The Britax Marathon
Credit: Abriah Wofford
Performance Comparison
This chart provides a comparison of the overall scores for all of the convertible seats we tested in this review. The Britax Marathon is shown in blue.
The sections below provide detailed information on how the Marathon performed during testing for each metric. The metric scores were used to determine the overall score with an emphasis on crash test results and ease of installation.
The Marathon is one of only 2 seats in the review to use EPP foam instead of EPS for energy absorption during a crash. EPP is more environmentally friendly and it does not off gas like EPS.
Credit: Abriah Wofford
Crash Test
The Britax Marathon earned the highest overall crash test score in the review. While it did not have the lowest recorded G-force data for either the chest or head sensor taken from the crash test dummy, it did have the lowest scores across the two. This seat, like all others in this review and for sale in the United States, meet or exceed the Federal safety guidelines outlined in FMVSS 213.
Therefore, each seat is considered to be safe. Our testing is designed to the same specifications as those used by the National Highway Traffic Safety Administration (NHTSA), so we could provide a true side-by-side comparison for each seat. Some seats, including the Marathon, have test results that indicate an additional margin of protection with G-force recordings that are significantly lower than the maximum allowable amount, and lower than much of the competition.
Credit: MGA
The charts included here show the data collected during testing from the sensors in the test dummy for the Marathon (shown in black). Also, the charts include the crash test data results for the seats that have the lowest recorded amount of G-forces during testing for comparison purposes (shown in green).
This chart show the head sensor data from the Marathon compared to the data for the Evenflo, the seat with the lowest recorded G forces in the head sensor
Credit: BabyGearLab, MGA Research
This chart shows the chest sensor data of the marathon compared to that of the Clek, which had the least amount of recorded G forces in the chest for this review
Credit: BabyGearLab, MGA Research
The Evenflo Tribute LX sensor recorded the lowest amount of G-forces in the head sensor during crash testing than any of the other products in this review. The Clek Foonf has the lowest level of G-forces recorded for the chest sensor in our review. The Marathon has the second lowest head G-forces and the third lowest chest G-forces for the group.
The Britax Marathon earned one of the highest scores in the review for installation using the LATCH system
Credit: Abriah Wofford
Ease of Install - LATCH
The Marathon earned a 9 of 10 for ease of installation using the LATCH system. The Marathon tied with the Roundabout with essentially the identical LATCH system, and the Chicco NextFit that sports what the manufacturer calls "SuperCinch".
Installing this seat using LATCH is a simple procedure and easier than using the vehicle belt. The LATCH anchors are positioned fairly well for easy connection to the vehicle anchors, but the seat base is close to the anchors, so depending on your car you might need to jostle it around a bit to get them connected. The seat feels stable when installed using LATCH, especially in the forward facing position and we liked that it feels like it's part of the car once attached. Loosening the strap is a little more difficult, but it isn't as hard as some and won't leave you crying or asking for assistance from a helper. Luckily, if you are like most families, you won't need to loosen the seat very often because it will likely stay in your car and only move occasionally.
The recline adjustment handle on the Marathon is under the seat where you will be unable to reach it after it is installed rear facing
Credit: Abriah Wofford
The recline adjustment handle is located on the base near the foot of the seat. This makes it difficult or impossible to adjust once the seat is installed securely. You will need to set the recline before you attach the LATCH anchors or before you tighten them.
The open frame design on the Marathon makes the belt pathway easy to start
Credit: Abriah Wofford
Ease of Install - Belt
Installation using the vehicle belt is a little more complicated, but it still managed an overall score of 8 of 10 for this metric. This ties with the Britax Roundabout, Chicco NextFit, and Peg Perego Primo Viaggio Convertible.
The high score for the metric is 10 earned by the Britax Boulevard ClickTight and the Britax Advocate Clicktight with the ClickTight installation system that makes installing the seat with the vehicle belt almost foolproof and super easy.
The Marathon pathway seems easy enough, but you will need to flip up the seat back cover to access the belt lock off
With the cover and seat back padding lifted you can see the green belt lock off on the seat back of the Britax Marathon.
The photos above show the belt path for forward-facing, including the portion of the path behind the seat with the lock off (right).
Removing the seat padding and cover is somewhat annoying when threading the vehicle belt for installation. Luckily, you shouldn't be doing this very often if you install the seat in your personal car
The rear facing belt path on the Marathon includes a belt lock off under the seat bottom cover and padding
The photos above show the belt path for the rear-facing installation, including the portion that travels under the seat and through the lock-off (right). Notice the seat cover and padding needs to be pulled away to thread the belt (left).
Installation with the vehicle belt is easy enough to get tight, but finding the belt path is a bit convoluted and requires somewhat of a disassembly of the seat cushions. Even then it is hard to see, and some testers felt it wasn't the best for larger hands. Adding to the problem is that the lock-off won't close if the vehicle belt is too tight and if it isn't tight enough the seat will not be secure. It is a bit like Goldilocks and the three bears for finding just the right level of tightness. At one point we had to use a screwdriver to get the belt lock off open. This might have been a result of the belt being too tight, but given that some other seats had lock-offs that are easier to use it is a bummer.
The recline angle for the Marathon can be checked for proper installation by using the line on the side of the seat
Credit: Abriah Wofford
The indicator for proper angle adjustment for proper installation is a line on the side of the seat that must be parallel to the ground when the seat is installed.
The Marathon buckle and chest clip aren't the easiest to use, but it does sport what the manufacturer calls an impact absorbing harness that has rubber attachments on both shoulder straps
Credit: Abriah Wofford
Ease of Use
The Marathon earned the second to the highest score for ease of use with a 7 of 10, which tied with Evenflo Tribute LX and the Peg Perego Primo Viaggio Convertible. The high score is once again earned by the Marathon's big Bros, the Britax Boulevard ClickTight and the Britax Advocate ClickTight.
Ease of use is an important metric in our mind because it reflects the daily experience that impacts how much you will like or loathe a seat.
The hook and loop narness attachment points on the Marathon cover do not work very well. The straps do not stay attached when placing baby in the seat, assuming you get them to meet up and attach in the first place
Credit: Abriah Wofford
The Marathon buckle isn't the best or the worst we saw in this review. It is an identical buckle to the one found on all the Britax options, and they fell somewhere in the middle of the group with several other buckles. It is on the stiff side, but it won't require two hands like the Diono Radian. The chest clip is also the same as the one found on the Britax Roundabout and we liked that you can release the clip without putting your hand underneath it. The seat cover has hook and loop attachments to the sides that are supposed to hold the harness straps open and out of the way, but they do not work well as the strap barely reaches the connection point and doesn't stay attached when the baby is placed in the seat.
The Marathon harness height adjustment is the easiest one in the group to operate
Credit: Abriah Wofford
The Marathon has the easiest to use non-rethreading harness height adjustment in the entire lineup of products (equal to the Britax Boulevard ClickTight and the Britax Advocate Clicktight). The size and shape of the handle that you squeeze to release the mechanism are perfect for most hands and squeezing it and moving the apparatus up or down to the desired position is smooth and potentially a one-handed operation. We like the non-rethread adjustment because it allows parents to make harness corrections quickly and easily the moment that you notice a need. These changes can be done with baby in the seat and take almost no time to master. The rethread options, on the other hand, are best done with baby out of the seat and often with the seat out of the car. The Marathon harness has ten different shoulder height options and two crotch strap positions for forward-facing and one for rear-facing.
The harness release button on the Marathon is fairly deep under the fabric
The tightening strap on the Marathon is so low on the foot it can be hard to use in the rear facing position
To loosen the harness, there is a button located on the foot of the seat under the fabric (left). It is easy to use and not too hard to find. The tightening strap is located right below it, and while easy to pull, it is tricky in the rear-facing position because it is tucked up against the vehicle seat (left).
The LATCH anchors on the Marathon click into the base when not in use. You can also see the red honeycomb impact absorbing portions of the base in this photo
Credit: Abriah Wofford
The LATCH anchors on the Marathon clip onto the back of the seat as does the tether strap clip. The extra strap for the tether is stored in a fabric pocket located at the top of the seat on the back of the seat cover. This storage system doesn't really keep the straps out of the way, and we preferred the seats that had dedicated pockets or hidden storage.
The users manual for the Marathon is located behind the cover but in front of the belt lock off on the seat back. We don't think this is the best location compared to some of the competition that provided a pocket
Credit: Abriah Wofford
The fabric cover is fairly easy to remove with only a minor hiccup in the process with the headrest mechanism. The fabric can be hand washed and laid flat to dry. The user manual is located under the seat padding against the seat back. It isn't the best place because it could get damaged and is somewhat in the way.
The Marathon would have scored higher for quality and comfort had the cover been more form fitting and less like a slip cover
Credit: Abriah Wofford
Comfort/Quality
The Marathon earned a score of 7 of 10 for comfort and quality. The high is 9 earned by the Chicco NexFit and the Britax Boulevard CLickTight and the Britax Advocate CLickTight.
The Marathon fabric is nicer than that on the Britax Roundabout and is one of the features that sets these very similar seats apart. It is a smooth fabric that is friendly to bare skin, and there is a softer more velvety fabric in the head region that would be especially gentle to the face. It appears easy to wipe clean and wasn't very absorbent in our tests. The padding on the seat is excellent all the way around, while some only offer padding in the seat bottom or minimal padding throughout, the Marathon offers a little bit nicer padding over the majority of the inside of the shell so children can be extra cozy. The infant insert adds more cushion, but it isn't something you can use for the duration of the seating life.
The back of the Marathon is open and shows the harness height adjustment. We think the seats with covered backs would be easier to clean
Credit: Abriah Wofford
The shell on the Marathon is not contained, and the back is entirely open with straps and bars exposed. This includes the non-rethread adjustment mechanism that has a lot of nooks and crannies where dirt and crud could build up and potentially impede the motion of the mechanism. We prefer the seat backs that are smooth and covered both in looks and practicality of use that keeps them clean and obstruction free, like the one found on the Britax Boulevard ClickTight.
The seat is made using Expanded Polypropylene (EPP) for its energy-absorbing foam inside the shell. This type of foam is less common than the Expanded Polystyrene (EPS) found in most seats and bicycle helmets. We prefer the EPP foam because it is less brittle and a little more forgiving should it be dropped or bent. Also, it is more environmentally friendly and doesn't off-gas like EPS, which is a big win in our book for little ones. Only the Britax products in this review use the EPP foam.
The Marathon has a rubber feeling edge that helps it avoid sliding too much. The bottom itself is not entirely smooth, but it also doesn't have parts that might damage a vehicle seat
Credit: Abriah Wofford
The overall fit and finish of this Britax product are nice compared to much of the competition. Everything on the seat stays in place, and it has a nice contained look about it with no parts hanging off or protruding where they shouldn't. The fabric fits the shell and frame snuggly without looking too much like a slipcover. It isn't as sleek and polished looking as the Chicco NextFit or the ClekFoonf, but it is still better than most. The bottom of the seat is not totally smooth. Although, there are no concerns with sharp corners or edges that might damage the vehicle seat if it rubs for a long time.
The Marathon weighs about 18 pounds, putting it about in the middle of the group for weight
Credit: Abriah Wofford
Weight
The Marathon is on the heavy side for the seats in this review with a weight of about 18 pounds. This doesn't compare to the hefty options in the review like the Clek that is closer to 35 pounds, but it is twice as much as the Evenflo that is just over 9 pounds and the lightest product we tested.
While weight isn't as important in this style of seat as it is in the infant car seats, because parents aren't likely to move the seat very often, it might still be of interest to parents who travel or frequent taxis or Uber. Eighteen pounds is probably more than you want to lug very far, but in the top 5 seats only the Roundabout is lighter with a weight of 16 pounds. On the bright side, the Marathon is narrower than all but 3 products in the review with a width of 18.5 inches. The smallest width is 17 inches shared by the Clek and Evenflo, which makes the Evenflo the lightest and smallest in the group.
BabyGearLab was founded by a Pediatrician Mom with a mission to provide a reliable, independent, source of information to new parents. Our experts have tested thousands of baby and kids products to share key performance, health, and safety findings. We spend tens of thousands of dollars crash testing car seats to inform our ratings. And, we combine our review work with gobs of expert parenting advice. To assure complete independence, we buy all the products we test ourselves. No sponsored content. No ads. Just real, honest, side-by-side testing by people who care.
