This 
Britax Marathon 70 Installation Review is a continuation of review Part I and Part II. The Britax Marathon 70, Boulevard 70, Boulevard 70 CS (Click & Safe), Advocate 70 CS and the Roundabout 55 are the all new Britax convertible carseat line.
Installation comments in 2005 Ford Freestar minivan (middle row captain’s chair) with LATCH:
The Good News – Everything! The seat practically installs itself, both rear-facing or forward-facing, if you’re using the LATCH system. Unless otherwise specified by your vehicle manufacturer – you can use the lower LATCH anchors until your child reaches 40 lbs, then you must switch to a seatbelt install. Many vehicle manufacturers allow the LATCH system to be used up to 48 lbs so check your vehicle owners manual for guidance. Britax recommends that the tether be used at all times. If using LATCH in a center seating position that doesn’t have dedicated lower anchors – you can use the lower LATCH attachments on the Marathon 70 if the spacing between those lower anchors is 20″ or less and the vehicle manufacturer allows it. The “Non-Handed” lower anchor attachments on the MA70 allow you to easily switch the connectors from the rear-facing to the forward-facing orientation. You just slide the straps back and forth along the metal bar and attach them to the lower LATCH anchors! No more “switching” the LATCH connectors like you had to do on the original Marathon model.
Now the big question: How much room does the new MA70 take up in the rear-facing position?
I’m happy to report that it actually takes up LESS room than the original Marathon model! Here are comparison pics of the Decathlon (similar shell to the original MA) installed in the captain’s chair of my van, then the MA70 installed with the level line level to the ground (the level line is the mid-point between the recommended 30-45 degree angle range allowed), and installed again with a single pool noodle to get it closer to the 45 degree recline that you would want for a newborn.
Needless to say, installation with LATCH in the captain’s chair of my van was as easy as possible and I was happy to see that that much hadn’t changed. The original Britax convertible models were well-known for their ease of installation. The rear-facing install took a little longer only because I had to find a place to attach the tether connector strap to tether the seat Swedish style.
Since I already had the seat installed at a recline angle appropriate for a newborn – I put my 20″ newborn-sized doll in the seat to see how it looked. This doll is about the size of a “big” newborn. Harness fit with the doll (without the newborn insert that can be ordered separately from Britax) wasn’t too bad. I used the body insert pillow that came with the seat but removed the belly pad and the harness strap covers because stuff like that just tends to get in the way with a smaller baby. You can see that the harness straps were still a bit over the shoulders but the fit was acceptable in my opinion. If this were a real newborn baby, I would probably recommend removing the rubber HUGS pads on the harness as well. The HUGS pads are optional when the seat is being used rear-facing but they are mandatory for forward-facing use.
Next up, installation in my husband’s 2000 Honda Accord. This vehicle has top tether anchors but no lower LATCH anchors so I had to use the lap/shoulder seatbelt to install the MA70 in this vehicle. The good news here was that the seat fit just fine in the rear-facing position even with the driver’s seat pushed all the way back. As long as you don’t need a 45 degree recline for a newborn – there was plenty of room to fit this seat. The bad news was that the new lock-offs (both rear-facing and forward-facing) gave me a hard time. You have to clamp them shut while there is still slack in the seatbelt and then attempt to pull all the slack out of the belt thru the closed lock-off. I found this to be counter-intuitive as well as counter-productive. Unfortunately, there is no way around this since the lock-off won’t shut if the belt is “pre-tensioned”. The good news regarding the bad news is that the lock-offs are optional if your vehicle seatbelt can be locked (locking latchplate, switchable retractor, etc). In the end, I was able to get better, tighter installs both rear-facing and forward-facing by bypassing the lock-offs and just locking my seatbelt using the switchable retractor.
Here is a video demonstrating rear-facing installation with lap/shoulder seatbelt using the lock-offs:
Is this the same as the Marathon g4.1? interested to know why it isn’t a recommended car seat?
Hi Eden, The Marathon G4.1 is an older platform from Britax. It’s still a good seat but we think there are better options for the price which is why it isn’t on our list of recommended seats.
Did you use both blue lock offs to clip the seat belt down?
In general, only one is needed. I usually suggest the one closest to the seatbelt buckle. You do need to verify in the owner’s manual, as guidance from Britax on this was not always the same for past models.
@Lorelei – you are correct that we recommend the seats with the deeper wings because we’re fans of the enhanced side-impact protection that you get with the Blvd, Pavilion & Advocate models.
i noticed that the marathon does not have headwings like many of the other seats i am considering. i like that it is lighter and smaller and cheaper, but safety first – do you think the headwings are important. i also noticed that the marathon was not on your recommended list. is this why? thanks.
So you don’t use tether strap for rear facing? My husband just tried to install our Britax roundabout and he said it doesn’t seem stable enough. Also the only tether strap connector we have is at the top of our backseat. Which is totally a pain! Please help! 🙂
Hi Renee – you can use the tether connector strap (aka D Ring) that came with your Britax convertible to create an anchor point for tethering the seat in the rear-facing position. You need to find a suitable location underneath one of the front seats to attach it. There should be info in the Roundabout’s instruction manual on how to tether in the RF position. This video should help: http://www.youtube.com/watch?v=n0XqandZ0uo&feature=related
I’m in search of a convertible that does not make my son’s head slump forward when he sleeps. How good is the Marathon 70 with this?
I would say it is probably good in that regard, but the similar Roundabout 55 is worth a look, too, in case the mechanism for the head restraint has any added thickness. I don’t have both on hand to compare at the moment, though.
Britax allows non-standard LATCH installs if the vehicle manufacturer allows it when the anchors are between 11 and 20″. That applies to any of their seats.
You wrote: If using LATCH in a center seating position that doesn’t have dedicated lower anchors – you can use the lower LATCH attachments on the Marathon 70 if the spacing between those lower anchors is 20″ or less and the vehicle manufacturer allows it.
Do you know if this is true for the older Marathon model, 65/CS?
oh yeah, thank you kecia for your help! as others have already stated, you rock!
I am happy to announce that the Britax Marathon 70 fits in the center of the back seat of my 2004 Volkswagen Jetta. The front seats are not completely pushed back but they are almost back as far as they will go. They are also reclined a bit. DEFINITELY NOT straight up!
The seat really does install itself….I worked and worked and worked b/c it seemed to easy. I pulled and tugged on everything and wasted a lot of time. Once the tether clips (LATCH system) are loosened a bit, all you do is snap clip into place and tighten the strap. Then, go to the other side and do the same thing.
Make sure you recline the seat before you put it in the car if you are installing in a small car. SO easy!
Would I like more car seats in the back of my Jetta? Absolutely not! I’ll be trading cars in August but for the time being, it fits just fine in the middle of the backseat with the front seats pushed back almost to capacity.
My little fella loves the seat and I do too! Good luck all!
LESLEE – I don’t have any personal experience installing the new MA70 on a plane but I suspect it will work well – especially in the RF position since it takes up less space than the previous versions front to back and you won’t have the issue of the latchplate sticking into your child’s back. In the past I’ve flown with an original Roundabout and Marathon and never had a problem with either or those. The base on the newer Britax convertible models is bigger but I think it will still fit fine in almost all coach aircraft seats. It’s going to be heavy to lug around but if you’re okay with that – it’s probably a decent option for traveling. The real bonus is how quick and easy it is to get a proper install with this seat in a variety of vehicles – especially if you’re using the LATCH system.
For more info and advice on traveling with kids in airplanes please see:
https://carseatblog.com/6599/airplanes-carseats-and-kids%E2%80%94what-you-need-to-know-pt-1/
https://carseatblog.com/6635/airplanes-carseats-and-kids%e2%80%94what-you-need-to-know-pt-2/
Also check out our “other transaportation” forum at
http://www.car-seat.org/forumdisplay.php?f=36
Hope that helps!
Hi!
How do you think this seat would do on an airplane? Also, how easy would it be to take this seat in and out of a variety of vehicles. We have a lot of upcoming travels which will mean using the seat in a variety of vehicles and planes. Also, do you have any recommendations on a seat that would be good for transporting in the ways that I have mentioned?
Thank you so much!
We just purchased the Britax Marathon 70s (12 month old twins) and had them installed rear-facing by a technician. Unfortunately, they are not reclined to the #3 position and now we have to take them back to the technician because I cannot fit my hand in between the car seat and the seat back to recline them because it is so tight. Is this correct? When properly installed rear-facing, is the recline lever unreachable? Thanks.
It is easy to make this mistake, even for a certified technician. You are correct that the seat should be in the most reclined position for rear-facing (position #3). Though it depends on the vehicle, it is quite common for recline mechanisms to be difficult or impossible to use when rear facing on many brands and models of convertible seats. Plus, it usually isn’t necessary to adjust it once you have it correctly installed rear-facing. If you are using LATCH, it might not be too hard to loosen it slightly, just enough to recline it, then tighten the adjuster straps again. Just make sure you haven’t gone past a 45 degree angle!
This is the same car I have & was thinking of getting one. Now I know I want it! Thanks for the demo!
My 12-month old son is tall and thin (90% height, 50% weight), with a very long torso. I am leaning toward the Marathon 70, but I’m concerned that he will outgrow it by torso length too quickly. Do you think this is a good seat for him, or is there another that might be a better fit?
The Marathon 70 should accomodate most all kids to at least 2 years old rear-facing, then for most kids until age 5 or more forward-facing. Some kids will go much longer. A few of the kids in the tallest percentiles (and all in the torso) will not last quite that long. If your main concern is rear facing torso height, the Learning Curve First Years True Fit line is a good choice and the Sunshine Kids Radian tends to accomodate kids well rear-facing for both height and weight. For front facing, the limits tend to be the top harness slots, and the Marathon 70 is pretty competitive with most other convertibles in that regard.
Kecia, Thanks for the reply. Yes, that is how it fits him so I guess it is a good fit, just different than his Graco infant seat. Also good to know we can bypass the lock offs completely. Thanks again for all your informative information here!
JESSICA – Does the harness fit your child like this? https://carseatblog.com/wp-content/uploads/2010/07/018.jpg
If so – that’s considered normal for this seat and perfectly acceptable. As for the lock-offs, I can’t promise that the forward-facing ones will be any easier to use but the good news is that you probably don’t need to use them if your vehicle was made after 1996. As long as your seatbelts lock in some way (check your vehicle owners manual for specific info) you can bypass the lock-offs altogether – just make sure your seatbelt is locked so the carseat doesn’t wiggle loose after it’s been installed tightly.
I love reading your blog. I have a question for you. We have a 2007 honda accord and top anchors for the top tether. It seems so awkward with the straps going around the seat, making it hard to put baby (9 months) in and out! is there anywhere else the top tether can go?? like, could we attach on the front seat rail somehow?
Hi- There are indeed two options for routing a tether when rear-facing. It sounds like you are using the “Australian” method, where the strap goes across the seat to the tether anchor designated for the vehicle seat, normally used when forward facing. The other method is often called the “Swedish” method, where you route the strap to a seatbelt anchor or rail under the front seats like you said. To do this, you would use the accessory strap included with your child seat. You can see some illustrations on pages 24 & 27 of your manual. You just want to make sure to loop the accessory strap around a fixed piece of metal that is attached securely to the frame and not likely to be pinched or cut if you move the front seats forward or backward.
We just purchased a Marathon 70 and tried installing it in our Subaru Outback (RF) No problem using the latch but we found the lock offs to be nearly impossible… are they any easier in the FF position? Also my 13 month old (22 pounds, 31″) seems too big for the crotch strap. The straps go across his thighs instead of around his hip/waist area. Is this how the straps are supposed to fit? I can’t move the crotch strap out because he is RF. Any thoughts on proper fit of the straps?
You can find some photos with the new infant insert accessory here-
http://www.car-seat.org/showthread.php?t=135236
Oh, and although #2 was a *huge* newborn, he’s turned out to be a little guy. He’s almost 10 months, and still has another harness slot to go on the SafeSeat. Even if we don’t get the new Marathon, he’ll be rear-facing for a while yet!