Re: Has anyone bought a True Fit yet?
Thanks, your 2 cents is much appreciated! I love how you form your posts (they make me consider other options and I never feel attacked), don't change a thing!
Thanks. That made my evening.
Thanks Trudy I didn't know that was a 35mph test. I just knew they released it in reponse to the CR study, I guess it makes sense it would be 35mph. I'm not too concerned about cocooning either, just trying to decide whether that's better than a RF tether. I posted a similar thread in the tech forum. That video posted here about the head going out of the seat cause the tether holds the seat back got me a little nervous. I had assumed even though the RF tether wouldn't allow the seat to move with the child, that it would still reduce head excursion just like a FF tether. Am I wrong?
Yes, NCAP standard is 35mph side impact, and the whole point of the CR test was that car seats should have to pass the same standards/speeds of tests as new vehicles do. The problem with CR test, is that due to the flawed methods, their tests equated to a 70mph side impact. So NHTSA redid the test using the 35mph side impact test that CR initially was trying to do, to see if they could reproduce the same failure rates.
Clear as mud, right?
Head excursion is a bit of a tricky thing, because in a ff'ing seat head excursion is measured from a point on the vehicle seat and the head can't cross the maximum distance from that point. During a crash, part of head excursion is also going to be the slight forward movement of the seat - if it's untethered there'll obviously be more movement, but even a tethered seat moves forward slightly as the webbing will stretch a little under crash forces.
The dynamics on a rf'ing seat are totally different though, so it's kind of like comparing apples to oranges in a way. Head excursion *should* be less with a rf'ing seat that is tethered, but that is going under the assumption that the rf'ing tether adds the same stability and reduces movement to the same degree as a ff'ing tether, and that isn't the case. Just to give you the image in your mind - ff'ing seat the tether starts tight, and the seat goes forward. Rf'ing, the initial stage of the crash the seat is going to rotate downwards towards the front of the vehicle - putting slack into the rf'ing tether. Then the seat will rebound, and at some point in the rebound the rf'ing tether will once again become taut and that's when the head excursion is going to happen.
My personal recommendations and belief about rf tethering is that in general it's a good thing and should be done whenever possible - with one exception - I would not rf tether the seat of a newborn child. We don't know for sure if there are increased neck loads on infants in a rf'ing tethered seat, but there is reason to believe that there could be. I wouldn't worry about a slight increase on an older child, but I'm not going to take any risk that might increase the neck load on a newborn. It would be a different story if we had seats like Australia where they have the rebound bar and then tether. (Australian tethering is where the tether goes from the back of the carseat shell, towards the back of the vehicle.) Australian tethering prevents or severely reduces the initial downward rotation, then the rebound bar reduces how much the seat can rebound. I would have no concern about increased loads on a newborns neck in that case.
And for the record, we're mostly speaking hypotheticals again, because we just don't have the real world crash data to say "under age "x" never use the rf'ing tether." or anything along similar lines. We don't have the real life experience to know if rf tethering changes the risk factors for injury - either positively or negatively. So in the meantime, parents are left to educate themselves and follow their carseat manuals. I wouldn't worry at all about rf tethering an older infant, but I'm just not comfy with the idea of putting a newborn in a rf'ing tethered seat. I'd use the seat untethered until the child got to be a little older. :twocents: