This review adds some additional comments and a photo followup to Kecia's reviews on our blog; you can read Part I, Part II and Part III on the all new [ame="http://www.amazon.com/Britax-Marathon-Convertible-Seat-Crimson/dp/B003OUWIK8/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1280334657&sr=1-1"]Amazon.com: Britax Marathon 70 Convertible Car Seat: Baby[/ame]. The Marathon 70 replaces the original Britax Marathon that has a 65 pound limit. The weight and height ranges listed are rear-facing for children 5-40 pounds, up to 49 inches tall with a seated shoulder height of 9 to 16.75 inches. Newborns may require an infant insert accessory, sold separately by Britax. It is listed forward-facing for kids from 1 year and 20 pounds up to 70 pounds and 49 inches tall, with a seated shoulder height of 12 to 16.75 inches.
[ame="http://www.amazon.com/Britax-Marathon-Convertible-Seat-Crimson/dp/B003OUWIK8/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1280334657&sr=1-1"]
[/ame]
Since Kecia's reviews are very thorough, I'm just going to post some pros, cons and comparisons and not ramble quite as much as I normally do. Please note that Part II of her review has some additional photos of an older rear-facing child, added after it was published. Pictures are worth a thousand words, so I'll finish with additional photos of various kids in the Marathon 70. I may add more in the future so please check back periodically! Please check the blog review links above for lots more photos!
Pros:
Cons:
[ame="http://www.youtube.com/watch?v=5aD3M0-MMNw"]YouTube- BritaxMarathon70.MOV[/ame]
Measurements- I know this is what everyone wants to know; how it compares to the old Marathon and other seats. Unfortunately, measurements are subjective. It depends where you place the ruler. Is the cover off? If the cover is on, how hard are you pushing down? If you show photos, does the angle of the camera perspective can make it look quite different than it really is? If you are comparing to another seat, did you match the installation angles? The vehicle seat positions and reclines? Add all these up and you can easily be off by a half inch or even an inch. Anyway, four of us took a look at the new Marathon 70 compared to the original Marathon (that had a Decathlon cover on it in the photos sorry!) and also a Boulevard. It was very hot outside so please keep in mind we were a bit rushed. Photos aside, we generally all agreed on the following (those present will add their own comments if they wish!):
Summary:
A great update of a very popular convertible child seat and is arguably one of the easiest to install [with LATCH] and easiest to use. With the optional infant insert, it should last typical kids from birth to around 3 years rear-facing and then forward facing to 5 or 6 years. Of course, it could be more or less for kids who are well above or below the middle percentiles for height or weight. For parents who are committed to keeping their kids rear-facing to 4 years or more, there are probably better choices. For everyone else, I don't think you will be disappointed with all the other improvements and the overall ease-of-use! As for safety, we have no way to compare with other models, but it sounds like Britax has made some great improvements there also. Though relatively expensive among convertibles child seats, the suggested retail price remains unchanged. Given all the enhancements, the Marathon 70 is better value than before and it is still made in the USA!
Obligatory advertising:
Please consider supporting Car-Seat.Org if you decide to purchase by buying through one of our Sponsors or our affiliates like Amazon using our links! While this review mostly pertains to the [ame="http://www.amazon.com/Britax-Marathon-Convertible-Seat-Crimson/dp/B003OUWIK8/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1280334657&sr=1-1"]Amazon.com: Britax Marathon 70 Convertible Car Seat: Baby[/ame], many aspects carry over to the other new models in the convertible line . These include the basic [ame="http://www.amazon.com/Britax-Roundabout-Convertible-Seat-Davenport/dp/B003OUWIJE/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1281414212&sr=8-1"]Amazon.com: Britax Roundabout 55 Convertible Car Seat: Baby[/ame] that has lower weight/height limits and lacks the no-rethread harness system and easy to remove cover. The [ame="http://www.amazon.com/Britax-Boulevard-Convertible-Seat-Onyx/dp/B003OUWILW/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1281414243&sr=8-1"]Amazon.Com: Britax Boulevard 70 Convertible Car Seat: Baby[/ame] has improved head wings for side impact protection and an optional Click & Safe version. Finally, the flagship [ame="http://www.amazon.com/Britax-Advocate-Convertible-Seat-Riviera/dp/B003OUWIPI/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1281414277&sr=8-1"]Amazon.Com: Britax Advocate 70 CS Convertible Car Seat: Baby[/ame] adds innovative external side impact cushions that can absorb energy from intrusion or impact with a door, pillar or adjacent child seat. All these convertibles share the same basic shell and frontal impact safety features. You can see the Advocate (left), Boulevard (center) and SafeCell energy absorbing base cutaway (right) in the photos below.
[ame="http://www.amazon.com/Britax-Marathon-Convertible-Seat-Crimson/dp/B003OUWIK8/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1280334657&sr=1-1"]

Since Kecia's reviews are very thorough, I'm just going to post some pros, cons and comparisons and not ramble quite as much as I normally do. Please note that Part II of her review has some additional photos of an older rear-facing child, added after it was published. Pictures are worth a thousand words, so I'll finish with additional photos of various kids in the Marathon 70. I may add more in the future so please check back periodically! Please check the blog review links above for lots more photos!
Pros:
- Same very easy LATCH installs with premium connectors and adjusters on each side, plus no more re-routing of the attachments when switching from rear to front facing and back.
- Easier harness height adjustment on top while installed; no more rethreading the harness or fiddling with multi-turn knobs on the side
- Innovative SafeCell design, reinforced harness and steel reinforcement bars promise exceptional frontal crash head excursion and safety performance
- 3-position recline (one rear, two forward) and 2-position crotch strap that is easily adjustable from the top; both are nice improvements over previous model
- Rubberized base helps keep carseat in place while installing and means no sharp edges touch the vehicle seat, but the flip side is that this could mask a somewhat loose installation in certain cases, much like a rubber protective mat can do.
- Forthcoming infant insert should accommodate typical newborns
- Same soft covers (most styles) are now easier to remove for cleaning
- 7-year lifespan (up from 6 years)
- No increase in MSRP and still made in the USA!
Cons:
- Would have liked increased seated torso height limits for kids in upper height percentiles, especially for rear-facing. I would guess that many kids will outgrow the rear-facing height limits before 40 pounds and the forward-facing height limits by 50-60 pounds, similar to the previous model.
- The new lockoffs are not as easy or intuitive as the old ones, as you must clamp them first and then tighten the seatbelt. This is balanced by the fact that the lockoffs and seatbelt path are easily accessed from the front. Plus, the lockoffs are optional and may not be needed in many vehicles. They probably become easier after you are familiar with them, but overall seatbelt installations seem pretty typical of most carseats.
- Would have liked to see LATCH allowed beyond 40 pounds (subject to vehicle manufacturer limitations of course).
[ame="http://www.youtube.com/watch?v=5aD3M0-MMNw"]YouTube- BritaxMarathon70.MOV[/ame]
Measurements- I know this is what everyone wants to know; how it compares to the old Marathon and other seats. Unfortunately, measurements are subjective. It depends where you place the ruler. Is the cover off? If the cover is on, how hard are you pushing down? If you show photos, does the angle of the camera perspective can make it look quite different than it really is? If you are comparing to another seat, did you match the installation angles? The vehicle seat positions and reclines? Add all these up and you can easily be off by a half inch or even an inch. Anyway, four of us took a look at the new Marathon 70 compared to the original Marathon (that had a Decathlon cover on it in the photos sorry!) and also a Boulevard. It was very hot outside so please keep in mind we were a bit rushed. Photos aside, we generally all agreed on the following (those present will add their own comments if they wish!):
- Rear Facing Height Limit: The new Marathon 70 looks a lot shorter side by side with the old one. Some of that is because it sits lower in the base. Also, the the new model is more angled so the child's bottom goes deeper into into the seat. Even so, depending on how you measure with the more rounded bottom, we felt the seated torso height based on the top of the outer shell (not the head restraint section) was over one half inch shorter on the new model. It looks slightly more in the photo with the ruler, mostly because the new Marathon 70 shell is farther back from the ruler due to the head rest. Three quarters of an inch shorter in practical use is a subjective estimate, perhaps a bit less depending how you measure.
- Rear Facing Leg Room: The new Marathon 70 has perhaps one half inch more legroom in a 2005 Sienna. Plus, it is angled a bit more so that may help too. In photos, it is doesn't seem like much difference, but it appeared to be a bit more in person. This could vary in different vehicles.
- Rear-Facing Installation Room: The new Marathon 70 takes up a little less room than the original when installed at a similar angle and with similar or identical vehicle seat positions and recline. You should gain an inch or more of legroom for a front seat passenger with all else equal.
- Front Facing Harness Limit: The top harness height setting goes a bit higher on the new one compared to the old one, maybe by one-quarter of an inch or slightly more. It's hard to compare exactly because the slots on the new one seem angled somewhat more than the original, but one of the kids who appeared to have outgrown the original Boulevard still fit with a little room to grow in the new Marathon 70. Our ruler measurements of the new Marathon 70 showed about the same rough increase compared to the original Marathon.
- Crotch Strap Room: The original Marathon has only one crotch strap setting. The new Marathon 70 has two, easily adjustable from above while installed. The closest setting is a little closer than the original. The outer setting is a couple inches farther out; great for older kids!
Summary:
A great update of a very popular convertible child seat and is arguably one of the easiest to install [with LATCH] and easiest to use. With the optional infant insert, it should last typical kids from birth to around 3 years rear-facing and then forward facing to 5 or 6 years. Of course, it could be more or less for kids who are well above or below the middle percentiles for height or weight. For parents who are committed to keeping their kids rear-facing to 4 years or more, there are probably better choices. For everyone else, I don't think you will be disappointed with all the other improvements and the overall ease-of-use! As for safety, we have no way to compare with other models, but it sounds like Britax has made some great improvements there also. Though relatively expensive among convertibles child seats, the suggested retail price remains unchanged. Given all the enhancements, the Marathon 70 is better value than before and it is still made in the USA!
Obligatory advertising:
Please consider supporting Car-Seat.Org if you decide to purchase by buying through one of our Sponsors or our affiliates like Amazon using our links! While this review mostly pertains to the [ame="http://www.amazon.com/Britax-Marathon-Convertible-Seat-Crimson/dp/B003OUWIK8/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1280334657&sr=1-1"]Amazon.com: Britax Marathon 70 Convertible Car Seat: Baby[/ame], many aspects carry over to the other new models in the convertible line . These include the basic [ame="http://www.amazon.com/Britax-Roundabout-Convertible-Seat-Davenport/dp/B003OUWIJE/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1281414212&sr=8-1"]Amazon.com: Britax Roundabout 55 Convertible Car Seat: Baby[/ame] that has lower weight/height limits and lacks the no-rethread harness system and easy to remove cover. The [ame="http://www.amazon.com/Britax-Boulevard-Convertible-Seat-Onyx/dp/B003OUWILW/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1281414243&sr=8-1"]Amazon.Com: Britax Boulevard 70 Convertible Car Seat: Baby[/ame] has improved head wings for side impact protection and an optional Click & Safe version. Finally, the flagship [ame="http://www.amazon.com/Britax-Advocate-Convertible-Seat-Riviera/dp/B003OUWIPI/ref=sr_1_1?ie=UTF8&s=baby-products&qid=1281414277&sr=8-1"]Amazon.Com: Britax Advocate 70 CS Convertible Car Seat: Baby[/ame] adds innovative external side impact cushions that can absorb energy from intrusion or impact with a door, pillar or adjacent child seat. All these convertibles share the same basic shell and frontal impact safety features. You can see the Advocate (left), Boulevard (center) and SafeCell energy absorbing base cutaway (right) in the photos below.