Question Explain the issue of downward rotation

ZephyrBlue · Apr 17, 2009

I'm running through options in my mind for the new baby on the way, and I'm wondering how much safer a seat with foot prop is. Under what circumstances (frontal, rear, side impact- size of child- etc) would a foot prop be safer than not having one? Does a rf tether provide any of the same safety benefits of a foot prop? I'm guessing No, because the Swedish seats have a foot prop AND a rf tether.

Any info would be appreciated

Pixels · Apr 17, 2009

A foot prop prevents downward rotation, which is an issue in impacts with a frontal component. It provides more benefits with larger children, which is part of why Swedish seats have them, and they RF until 4-6 years of age, whereas we are currently stuck at 35 pounds RFing.

Australian style RF tethering (tethering over the top, to the normal FFing tether anchor point) provides much, if not all, of the same benefits as a foot prop. Swedish style tethering, down and toward the front of the vehicle, provides the exact opposite benefits as the foot prop. Swedish tethering prevents the seat from rotating up and back during the rebound phase of a frontal impact (or during the initial phase of a rear impact).

ZephyrBlue · Apr 17, 2009

thanks pixels. so, the swedes have the right idea- the rf tether helps w/the rebounding and the foot prop prevents downward rotation.

since us seats only rf to 35lbs, is downward rotation not an issue? more succinctly, i guess, is downward rotation only an issue with the higher rf weight seats (ie- up to 55lbs)?

joolsplus3 · Apr 17, 2009

Here's what it looks like... http://www.carseat.org/Technical/tech_update.htm#angleRF
And here's with a foot prop (or braced, same thing) http://www.youtube.com/watch?v=K62Ea8Fs4ng

What happens is when the seat dumps down there's the potential for the shoulders to have excessive force into the harness, and the head to dump out the back and strike the front seatbacks (and this graphic shows how bad head injuries can be to rearfacing kids... http://carseatblog.com/?p=34)

Australian tethering is like a footprop, it keeps the seat from rotating downward. The Britax Babysafe had a base with a footprop (but it was so expensive no one bought it

).

I wouldn't worry very much about a properly used and installed RF seat rotating too far downward (that's what the NHTSA test measures), and making sure that the straps are at or below the shoulders and the head being at least one inch from the top of the seatback is a safeguard against the head flying out, too. It's those large babies in very small infant seats that are the ones at risk from overrotation :twocents:

joolsplus3 · Apr 17, 2009

Sorry it took me so long to post, was digging up linkies, lol.

edit, yes, it could be very large children who rotate down more, but the seats are tested with 35 pound 3 yo dummies and pass the NHTSA test just fine, so it's not 'our' toddlers at risk, kwim? 'we' use our seats right

ZephyrBlue · Apr 17, 2009

thanks jools

i can't rep you again yet till i spread it around, lol!

i'm really torn; on one hand, i know our seats, used correctly, with a rf tether are very safe. but then i think about the foot prop and rf tether of the hwh rf swedish seats and they really seem like the best of both worlds, kwim?

joolsplus3 · Apr 17, 2009

Yeah, I really do understand...it's 'good enough', but why can't we get our hands on 'better'? Darn it, I want the 'best'! (There's a Recaro contraption, a base with a foot that LATCHes in and you can snap all their seats to it, I think, it' just seems so obvious. Like, why can't the automakers invent something like that?)

ZephyrBlue · Apr 17, 2009

to import or not to import, that's the question

wait till i tell dh i'm looking at a $500+ car seat. that should be an amusing conversation

JerseyGirl'sMama · Apr 17, 2009

joolsplus3 said:
And here's with a foot prop (or braced, same thing) http://www.youtube.com/watch?v=K62Ea8Fs4ng

On a side note, did anyone read the comments on this video? Can someone who has a youtube account reply to the last response? And Lol that someone thinks a piece of regular tape could hold a head still in a crash.

joolsplus3 · Apr 17, 2009

Maybe you can't see the expanded version with all the comments (since you don't have an account?), one of us (CandCfam) already tried to get them to understand the tape isn't doing anything. I think it's a losing battle, though...

wendytthomas · Apr 17, 2009

Also keep in mind that we don't need foot props here. Swedish seats are made for bigger kids and they have the leg room to accommodate them. So they stick out past the backseat edge a bit. They'd fall on their bottoms if it wasn't for the foot prop. Our seats don't have that huge gap for legs, so they sit on the backseat, with the backseat acting as a foot prop.

Wendy

JerseyGirl'sMama · Apr 17, 2009

joolsplus3 said:
Maybe you can't see the expanded version with all the comments (since you don't have an account?), one of us (CandCfam) already tried to get them to understand the tape isn't doing anything. I think it's a losing battle, though...

I was actually referring to the 'Ischultz459' poster:

its not a very convincing video for many reasons...first off there are alot of variables to consider. At what speed was this test performed? Most backseats in vehicals are not as long as the seat in this video allowing for a resting place for your legs, I see longer legs being thrown up over the childs head potentially causing neck and back injuries, I also see the childs legs hittiing the front seat on impact causing, broken legs, hips, backs and neck injuries all depending on the speed.

I did see the comments back and forth about the tape (from a year ago) including 'CandCFam's' comments, and found that somewhat amusing. I was just hoping someone could comment on the 'legs being thrown up causing head and neck injuries', and 'broken legs, backs, hips and neck from the legs being too long' stuff.

finn · Apr 18, 2009

wendytthomas said:
Also keep in mind that we don't need foot props here. Swedish seats are made for bigger kids and they have the leg room to accommodate them. So they stick out past the backseat edge a bit. They'd fall on their bottoms if it wasn't for the foot prop.
Wendy

I must say I have one of the biggest Swedish rear facing seats and a small car with short backseats & the seat doesn't stick out over the edge, it is inline with the edge but not over it.

I like the Swedish tethering, it feels really secure, I also like and understand the Australian tethering, keeping in mind that all Australian rear facing seats have anti-rebound bars, but only rear face to 12kg, I couldn't imagine not tethering a seat and would love it if someone could explain to me how American tethering prevents downward rotation.

ketchupqueen · Apr 18, 2009

American tethering? You mean rear-facing? It doesn't, really. It's more of benefit in side-impact crashes than anything else, as I understand it. Also helps control rebound.

joolsplus3 · Apr 18, 2009

finn said:
I must say I have one of the biggest Swedish rear facing seats and a small car with short backseats & the seat doesn't stick out over the edge, it is inline with the edge but not over it.

I like the Swedish tethering, it feels really secure, I also like and understand the Australian tethering, keeping in mind that all Australian rear facing seats have anti-rebound bars, but only rear face to 12kg, I couldn't imagine not tethering a seat and would love it if someone could explain to me how American tethering prevents downward rotation.

Right to KetchupQueen... there's only Swedish or Australian, no such thing as American tethering. Most of us prefer Swedish to prevent rebound, it's Australian that prevents downward rotation.
Here are pictures of Australian (scroll down to the leopard print Roundabout, lol) http://www.angelfire.com/wa3/isakswings/ratetherrf.html

TerisBoys · Apr 18, 2009

joolsplus3 said:
http://www.angelfire.com/wa3/isakswings/ratetherrf.html

Oooooh - Anglynn's page! Talk about a blast from the past!

Question Explain the issue of downward rotation

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