RF tethering for an infant?

At what age do you tether rear-facing for an infant? At what age do the benefits begin?

DS is almost 11 weeks old and I am going to try him out in the Radian this week.

Would love to hear opinions on this.

I don't believe there's any data one way or the other on this. It's a matter of opinion. The Swedes tether from birth, I believe. I tethered Piper from birth. Now I don't know if I'd do a newborn, but I also don't know that there'd be harm from it. Some people may wait until a baby has good head control. Others may do it from birth. Whenever you're comfortable with it.

Wendy

Yeah, that :thumbsup:
Even the tethered seats had neck force measurements well below what the government max is (maybe a bit higher than untethered seats, but still lower than the max allowed). I think if the seats that allowed tethering were concerned that it would cause injury, they'd put a minimum weight or age limit. Since they allow it from 5lbs/birth, then I don't think they are concerned it will add a risk of injury to young babies :twocents:

I am planning on trying out my ds, 3mo adjusted age, in my MA this week. I am curious how he fits in it now at 9lbs. I will be RF tethering it for sure. He rides in a Britax Companion otherwise.

I tethered from birth and don't regret it. I think an ARB is BETTER for a newborn if you have a choice between the two-- but I'd choose either one, or an infant seat that allows the handle up, over a seat with no rebound control. That's my personal feeling on it.

Tethering does increase neck loads, but as PPs have said not above the max. The study I read said that probably the greatest benefits come from tying the carseat to the vehicle tighter (tighter overall install) and increase in side impact protection. Basically, the greatest benefit from top tether would be if you had steeply sloped seats, installed the lower anchor belt or seatbelt tightly, then used the top tether on a Radian* to get the seat as reclined as you could force it.

I read somewhere, don't know where now, that the benefits in additional SIP outweigh the additional neck strain somewhere around 9 months old. I tethered my DD's seat at 7 months when I got it, I couldn't not play, and it was close enough for me, knowing that it's not really unsafe at any point. If I had a newborn I probably wouldn't tether unless I needed the assist on the recline angle.

* The Radian is the only seat that allows you to use the top tether to adjust the recline angle rear facing.

How do neck loads differ with an ARB vs a rf tether? How does much differ between the 2?

With both ARB or RFing tether, the seat goes through the normal downward rotation phase of the crash, just like an untethered, non-ARB seat would. It's during the rebound phase where the differences lie.

A non-tethered, non-ARB seat rebounds until it runs out of energy and falls back down to the seat, or else the seat will bump into the vehicle seatback at the top of the rebound. The child moves with the seat and the head stays pretty well aligned with the body.

A tethered seat will rebound until it runs out of slack in the tether (the slack that appeared when the seat was rotating downward), when it will be jerked short by the tether. The seat stops the rebound action but the child does not. The child's body is restrained by the harness, but the head is not, so the head moves forward, causing some neck strain.

A seat with a rebound bar will rebound freely until the ARB contacts the vehicle seat cushions. The ARB will compress the seat cushions as it slows the rebound action. Again, the child's body is stopped by the harness but the head is not. The time it takes for the seat cushion to compress as the ARB presses into it provides a little ride-down time just for the stopping of rebound, so it should be less of a sudden stop vs a RFing tether.

There was a study done on RF tethering, including both Britaxes and seats that don't allow for RF tethering. The numbers on neck loads for seats with RFing tether vary from seat to seat. I don't think we have any numbers on neck loads for ARB seats.

Thanks. What I wasn't seeing in my head was the arb compressing the vehicle seatback. It makes sense though

Thanks Ketchup for that explanation. I think I feel most comfortable with not tethering at his age.

KQ - I know that there is a post around here somewhere that talks about the difference in HIC with the anti-rebound bar TF. In terms of stress on the neck it's much superior to a rf'ing tether.

To answer the OP, I recommend to parents that they need to do their own research as to whether or not they want to rf tether their seats, and that if they choose to tether I recommend waiting until baby is 4months old at a minimum. I'm not comfortable with rf tethering prior to that because we know it does increase neck loads.

Yes, I know the ARB is superior in that regard. That's why I'd prefer it for a newborn. I still PERSONALLY prefer any kind of rebound control to none-- especially in my vehicle. I think the vehicle dynamics have to be taken into account as well. Rebound control is going to be much more important in trucks, or with kids in the last row of a minivan with a small "trunk" space, or in a small car, than with a child in a larger car or the middle row of a minivan or SUV.

I have never seen a newborn come in in a convertible with RF tethering capability. Most people I see use infant seats. If the infant seat handle is allowed up, I do recommend that, and explain why. (I also let them know whether there are any disallowed positions for the handle, in case they decide not to.) All the newborns in convertibles I've seen were seats with no capacity to tether RFing. If I did see one, though, I would definitely expound both the benefits and risks, and explain that some people are comfortable with it from birth, and some not until the baby is 4, 6, or even 9 months old. I would give them resources for further research if they wished to do it and let them make the choice.

Like I said, I don't usually see babies in convertibles that RF tether at all until 9-11 months. The SR32s and Keyfits are really popular with the population I see so many of them aren't even moving to convertibles until then. Among seats that RF tether I do see, most are Britaxes, and many of the parents chose them because they can.

Wow, I am constantly learning on here. I was just doing a bit of research to see if the RF tether was required on the radian, and I'm glad I did. I just installed it in the Sienna RFing, and I'll try to take a pic tomorrow to get some opinions. I think I'll skip the RF tether for a while.