Is rear-facing tether really a good thing?

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honeybee03

New member
Ok, so I thought I absolutely had to have a car seat with RFing tether. I've seen the crash test videos about how the baby's face slams into the seatback on rebound, and they scare the crap out of me.
But then I came across this info from this link

http://www.carseat.org/Technical/tech_update.htm#rearfacFF

Top Tether, rear-facing

Only a few CRs in the U.S. have tethers for rear-facing use, but these are common in some other countries. Australia has tethered the top of infant restraints to an anchor positioned behind the vehicle seat for many years, and the most popular rear-facing "capsule" will not work properly if it is not tethered. Australians have also generally kept infants rear-facing until only about 6 months, when they start to use a forward-facing and virtually-always tethered restraint. Tethering a rear-facing CR toward the rear of the vehicle, which describes the Australian method, limits the downward rotation of the restraint and child during a frontal crash but does nothing to affect initial stability, rebound, or rear-impact.

Sweden has always used rear-facing restraints for children up to 4 years old, when they are moved directly into boosters with lap-shoulder belts. These large rear-facing restraints, which are set several inches away from the vehicle seatback to provide leg room, must rest against a vehicle structure, such as the instrument panel (unless there is an air bag) or the back of the front seat to keep them from falling over. Since the CR and its occupant can be tall and heavy, the Swedes have also tethered the backs down to the floor to eliminate rearward rotation during rebound or rear impact. The Swedes also have some small infant-only restraints that are not tied to the floor but do use the shoulder portion of the lap-shoulder belt to wrap around the "front" (the child's back) of the restraint to limit rotation during a crash. This installation method is used throughout Europe for frontal crash protection, but there is little effect on rebound or rear-impact motion.

The first U.S. infant restraint, which is the model for subsequent ones, did not use a tether in either direction nor a shoulder belt, but it worked very well. During development, the engineers observed that it turned over toward the vehicle seatback after a crash test and, largely in order to justify what happened anyway, they called this the "cocoon effect." There was also some justifiable concern that the small infant's neck might be injured on rebound or rear-impact unless the restraint were allowed to freely rotate in this direction. Justified or not, this concept has remained and seems to make intuitive sense. The counter-argument that the infant's head will "slam" into the seatback and be injured on rebound has not been validated in over 30 years of crash experience.

Britax, which has operations in Australia, Sweden, UK, and Germany, as well as in the U.S., devised a means to tie a traditional U.S. rear-facing convertible down to the base of the front seat structure to give it a firm installation and help the parent achieve something close to a 45° back angle, or more upright as appropriate. This tether does achieve a very secure installation, which is reassuring for parents, but it does little, if anything, to improve protection in a frontal crash. Downward rotation will likely be limited more by the back of the front seat (see Rear-facing CR resting against front seat) than by any cushion compression achieved with a tight downward tether. Another concern is that parents may use the tether to make the CR too reclined. Finally, tests conducted by a competitor a few years ago showed that dummy neck loads increased significantly when the restraint was tethered to the floor in both frontal and rear impacts. This would be more of a concern with the youngest infants than with children over 9 months to a year, but the competitor decided not to offer rear-facing tethers.

The restraint models on which the rear-facing tether is offered, however, can accommodate a child up to 33 lb rear facing, and for this usage the limit on rebound or rear-impact motion may be beneficial. Although crash experience indicates that rebound of infant-only restraints in frontal impacts does not cause serious injury, similar movement of a rear-facing restraint can also occur during a severe rear impact or offset rear impact, which can result in serious injury or death if the infant's head hits the rear door pillar of a sedan, the rear window of a pickup, or some other hard surface. As larger and heavier infants are carried rear-facing, the chance of an infant's head hitting a hard part of the vehicle is greater. Tethering a rear-facing convertible CR to the floor can reduce the risk of head and facial injuries in rear and side crashes by reducing head excursion.

Britax also acknowledges that one can route the tether rearward (Australian method) to the normal top tether anchorage, but this configuration has been given second priority. Of the two methods, this one is likely to have the most benefit in a frontal crash if there is rotation room in front of the child restraint. In practice, however, convertible restraints barely fit into back seats anyway, so the rearward tether may have limited use, except in vans.


I don't understand a lot of this, but it makes it sound like tethering it is a bad thing??? I will be getting a Radian, with has tethering in the RFing postion. Should I not tether it until its FFing? My DD is 9 months old & 18lbs. It also made it sound like it was good for older children, but not younger babies??
Any techs, I could use your opinion. Also, which method (swedish or australian) is better, and why?
 
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thepeach80

Senior Community Member
The Radian only tethers the Swedish way and Britax just came out sayin that's the only way they want their seats tethered too. I find the argument a little vague for myself. The only thing they had to say is a competitor found it was too hard on a child's neck. Where is the proof? Britax is an internationally known carseat company, they don't just make things up as they go along, all their seats and tethers etc are all extensively tested worldwide in many settings and I would go w/ their reccomendation over Cosco saying they don't offer tethers b/c they feel it's bad.
 

bbartlettnfld

New member
RF tethering

RF tethering is a nice bonus, but its not a nessisity. If a babys head actually came into contact with the vehicle seat back then it must have been outside the "wings" of the seat, for this to happen the harness was possibly way too loose.. So if the child is correctly restrained I would say that they will not impact the seat back as they will be held back into the seat by the harness.
If heads hitting the seat back was a common occurance every seat out there would have a RF tether. I also think that the "coccoon" effect may pose a safety bonus as the child is possibly protected from glass and other things intruding into the car by being "cocooned". Now weather or not this is actually true in context I have yet to witness.. It just sounds comforting.
BethAnn
CPST
 

SafeDad

CPSDarren - Admin
Staff member
I think there will certainly be additional forces on a child's neck in a seat that is tethered RF, at least in the initial part of the rebound. The same point was often used against top-tethers for front-facing seats.

The more important things to consider are:

1) The rebound is going to stop eventually even if it is not tethered. At that point, there will also be additional forces on the child when the seat stops moving. How large these forces are depend on how abrubt the seat/child stops moving.

2) Even if there are higher forces on the neck, are they a major risk? So what if the forces are double if that is still much less than what the child can withstand? For example, babies are often turned front-facing in Australia around 9 months, apparently with no increased risk of spinal injury. Certainly, the forces on the neck in that configuration are a lot higher than in a tethered RF seat.

We don't really have any statistics to show any increased or decreased risk of a rear-facing tether. I happen to think they are a good feature, especially for older babies. On the other hand, rear-facing is so safe inherently that using or not using a RF tether probably isn't going to make much difference either way.

Also-

http://www.car-seat.org/showthread.php?p=31603

http://www.car-seat.org/showthread.php?p=26636
 

Victorious4

Senior Community Member
I have a personal preference for not tethering newborns RF ... but when keeping toddlers/preschoolers RF I can see tethering being safer -- to prevent the head from impacting the vehicle (also: Britax customer service told me that the safest way to secure my kiddo at the verge of outgrowing the RF limits is to definitely tether).
 

Beana

New member
So would it be better to tether if the only option was to a bar under the seat or to the top tether in back of the same seat? I've gone back and forth on tethering my RF RA and still don't know what to do. My dd is 26 lbs and 20 months. She is still RF but I took the tether off since Britax no longer recommended tethering under the same seat or even to a bar just under the front of the same seat. Unfortunately, I don't have any other tether options towards the front of my van.
 

honeybee03

New member
Wow, thanks for those threads, very informative. I didn't realize this was such a contorversial issue, I guess I should have done a search first before creating a thread.
I think when I get my Radian, I will definetely tether it. Though now I am inclined to call Pontiac to see what their suggestion is on whether or not to do it in the Bonneville, or if they have a suggestion on what to use to tether it to.

I just wanted to comment on what I think about the "caccooning"....
I thought about what people have said about it putting increased forces on the neck, but then isn't it the same thing with the forward facing tether(as was pointed out in the thread that I was linked to)?? When they are tethered FFing, no the seat won't move with them to "cushion" the effect, but their neck extends farther out when the tether isn't used.
Also, I think maybe its kind of like the same thing as how you are supposed to brace the carseat againts the vehicle seat in front of it. Because its better for it to already be touching the seat, than for the seat to start moving and then slam into the seat in front of it (so then it should be better for the restrain to be braced from the other direction too, instead of starting to move forward on rebound, and then suddenly stopping, right?).
Also, people were saying that the sides of the shell should protect the infants head from slamming into the seat (if they are in tight enough) At first I thought this made sense, but today when I put Ryleigh in her carseat, I looked at it and saw that the sides of the shell don't go past her head in the first place, in fact, they barely go past her ears. Maybe on a seat that has side impact protection, it would protect the infants face, but on a "normal" infant seat (I have a graco snugride) the sides of the shell aren't deep enough. From looking at the Radian car seat, it doesn't look like the sides extend far enough to protect her from any head injuries either.

Thanks, I definetely feel better about choosing to tether now :D
 

SafeDad

CPSDarren - Admin
Staff member
As you said, Britax stopped allowing the seat to be RF tethered to an anchor under the vehicle seat used for installation. Supposedly, it was temporary until they could do some additional testing and update their information, but it's been a couple years now.
 

SafeDad

CPSDarren - Admin
Staff member
Exactly. The tether is mainly to reduce head excursion, whether in a FF seat or RF seat tethered in the Swedish method. There may be other advantages, including the ability to get the desired RF recline and more stability in side impacts and rollovers. Again, I don't think any of the benefits are more than a minor bonus, nor would the possibility of any increased load on the neck be anything more than a very small increased risk. In the end, if it is allowed by the child restraint manufacturer, you can be pretty sure they wouldn't want the liability for recommending something that is unsafe or unknown.

Unfortunately, vehicle manufacturers don't tend to know much about RF tether locations, especially the general customer service reps. I doubt Pontiac will be much help to you.
 
C

childrestraintsafety

Guest
The thing with tethering 'Australian Style' is that over here (I am in New Zealand, but we have Australian restraints) they also have what we call 'stabilizing bars' (otherwise known as rebound bars) which, from what I have gathered are not on United States Standard convertible car seats. Tethering 'Australian style' will not stop the seat from flipping/'cocooning' towards the back of the vehicle on rebound or in a rear impact, that's what we have stabilizing bars for. I couldn't say what, if any benefit it would have on an American seat, since they lack this feature (except for some infant seats).
 

SafeDad

CPSDarren - Admin
Staff member
Exactly. In fact, in the USA, Britax switched from their Versa-tether (Handle with Care) to a rebound bar (Companion&Babysafe) in their infant seats. As I mentioned in a previous thread, the thought is that the rebound bar tends to "give" a little more than a [Swedish] tether. This would increase the ride down time of the rebound more and also lower the forces better than a tight tether or no tether at alll. It should still give a reasonable reduction in head excursion, too.

For older babies and toddlers, the thought is that the Swedish style tether is just fine, as they generally can tolerate the forces in a properly used front facing seat with a 5-point harness, anyway.
 
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