With American/Canadian RF seats, during the crash phase, the top of the seat dumps down toward the floor. It can rotate as far as 70 degrees (almost flat). When the seat is rotated so far, a lot of the restraining force is placed on the top of the shoulders and/or lap straps.
Yes, I am well aware of basic RF crash dynamics.
A footprop nearly eliminates downward rotation. Add in the fact that European seats can be installed more upright (up to 5 degrees, I believe), and while you won't completely eliminate ramping up, you certainly reduce it by a large amount.
Bolded part is my point. I haven't seen many (any
...) crash test videos of RF+foot prop seats; but in the (much circulated) braced RF seat crash test
(which I imagine is quite similar in function to a foot prop. more so than an ARB or RF tether, though aussie style is prob. closest?) about the only movement the child has is ramping up. Sure it's not a
lot of movement, but it would be more movement with the straps placed above the child's shoulders, and still more if the geometry of the hip straps are high on this particular child (no way to check it out in advance with an imported seat).
I'm not trying to argue (just trying to understand), but am I mistaken in imagining that crash forces not absorbed by the seat, is then transferred to and absorbed by the child. Namely, tops of the child's shoulders in this case. (Maybe I'm trying to apply ride-down theory to an incorrect situation?
)
In any case, it seems to me, that according to
this child's doctor, the main concern is any pressure on top of the child's shoulders. Having RF shoulder straps placed above the child's shoulders would reduce the pressure, but probably not eliminate it. Any amount of ramping up in a crash would likely result in an
impact of the child's shoulders into the top of the shoulder straps. This seems like the worst possible scenario to me.
Given the option to get a restraint that has no regular contact to the shoulder it still seems like the only viable choice. Though if a shield seat was NOT an option, I would suggest a britax convertible, given it's known low hip straps and ability to RF tether aussie style.
We may just have to agree to disagree. :thumbsup: