Crotch straps and safety...

UlrikeDG

Admin - CPS Technician Emeritus
Can we discuss this? I've seen a lot of posts lately about how horrible it is for the crotch strap to be positioned too far back, and I'm really not getting this at all.

I remember someone (I'm pretty sure it was Tom Baloga, back in the day) discussing this and saying that moving the crotch strap forward actually decreases head excursion, but it does so by increasing hip excursion. He said that he preferred the crash dynamics with the closer crotch strap, but I don't remember what, if any, other details he gave in the discussion.

Does anyone remember what I'm talking about? Any other information on this topic that I should know about?
 
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Chameleon

New member
I don't get it either. My son sits on the MA buckle as well as the BLVD buckle and I just don't see a problem. It still doesn't squish him, nor is it a problem. He doesn't know any different and never complains. I think the majority of people who have a problem with the buckle are just having a "cosmetic" problem and they just don't like that their DD or DS is sitting on the buckle and perceive a problem when in fact there probably isn't a problem at all. Just my opinion.

You have to wonder though that as many people that want a futher out crotch strap instead of the closer one, why would Britax not allow children to use the farther out crotch strap on the Regent until XXlbs. I forget the weight but I think it's 50. I think that they are on to something safety wise.
 

jwren

New member
I could see how if the crotch strap was too tight and the top straps were correct it seems to me the child would move forward with upper body more than the lower... If it were balanced than they would all move in harmony together with the same forces all over.. Imagine this... say you have a lapbelt only and you hit the brakes to crash.. the lap belt holds what..only your waist, which leaves the rest of the body flowing forward...head, upper body, chest, legs...Imagine the crash test videos...my thinking is if it's too tight the forces go to the top and bottom more than the middle, so it's not even. If it's all distributed evenly... top straps, crotch straps...than the forces will distribute across the whole body not just the waist.. using the lapbelt as an example is exagerating but I was trying to point out why being so tight there could possibly be a bad thing... (also a lap belt is obviously much different than a crotch strap on a 5 pt harness...) Of coarse real life testing really needs to be done, as these are just hypothosies...;)

BTW: when we think of car safety we should always look at the racing industry as they are always ahead of the game... I would love to see all cars have not 3pt belts for adults, but 4-5 pt harnesses and for kids they should have the 5-6 pt harness built in to fit all little kids.. I would love to see the day that you could just buy a car that had a 5 or 6 pt harness built in the seat and was adjustable by height.. here is an example of the racing industry being on top of it...meanwhile we know this is safer for all, yet we still have a three pt belt in all cars... and nothing much for kids... sad isn't it...:(
http://autoracingsport.com/nascar/nascar-now-requiring-six-point-belt-harnesses-for-drivers/

PS: for boys the 6 pt might actually be more comfy... hint hint Britax...



Can we discuss this? I've seen a lot of posts lately about how horrible it is for the crotch strap to be positioned too far back, and I'm really not getting this at all.

I remember someone (I'm pretty sure it was Tom Baloga, back in the day) discussing this and saying that moving the crotch strap forward actually decreases head excursion, but it does so by increasing hip excursion. He said that he preferred the crash dynamics with the closer crotch strap, but I don't remember what, if any, other details he gave in the discussion.

Does anyone remember what I'm talking about? Any other information on this topic that I should know about?
 

UlrikeDG

Admin - CPS Technician Emeritus
The more I think about this, the more I'm convinced that there are two issues with moving the crotch strap forward:

1) Now the child's hips will move forward and his genitals will "slam" into the strap, where before they were already right there, allowing for slower deceleration and less energy transfer. Energy transfer is important. Those who have taken the tech course know that injury is caused by "the transfer of energy to tissue." (That energy can be thermal, mechanical, electrical or chemical.) "Ride down is the extension of time when the forces are felt by the occupant during a crash. A quick change in speed is what causes injury." A tight CR installation and a snug fit of the harness increase ride down time and reduce injuries.

2) Additionally, moving the strap forward would increase the percentage of the crash forces being transfered to the child's lower body vs his upper body.

So, as counter intuitive as it is to parents, moving the crotch strap out, creating "more room" for the child's genitals could actually significantly increase the amount of crash forces being exerted to the child's genitals in a frontal crash.
 

UlrikeDG

Admin - CPS Technician Emeritus
Imagine this... say you have a lapbelt only and you hit the brakes to crash.. the lap belt holds what..only your waist, which leaves the rest of the body flowing forward...head, upper body, chest, legs...Imagine the crash test videos...my thinking is if it's too tight the forces go to the top and bottom more than the middle, so it's not even. If it's all distributed evenly... top straps, crotch straps...than the forces will distribute across the whole body not just the waist.. using the lapbelt as an example is exagerating but I was trying to point out why being so tight there could possibly be a bad thing...

You've got it backwards. The problem with a 2-point restraint isn't that the bottom is "too tight", but that the top is "too loose" (i.e., nonexistent). The other issues with a lap-only belt aside (submarining, etc.), one of the major risks is that an object in motion keeps moving until it is stopped by something, and with a lap-only belt, the "something" that stops the person's head is often an hard interior surface of the vehicle. The increased risk is for head injury, not hip injury.

Loose straps are always a bad thing. They reduce ride-down time and increase the risk of injury. Loose upper straps increase the energy transfer to the upper body, and loose lower straps increase the energy transfer to the lower body.
 

snowbird25ca

Moderator - CPST Instructor
One other thing of interest, is that the Radian specifically instructs parents to choose the crotch strap position right at, or just under the child - and to never use a position forward of the child. Must be some reason for that?

I'm also of the opinion that crotch straps are just one of those things somebody worried about out loud and then others jumped on the band wagon. It's probably kind of like how people worry about kids legs being uncomfortable rf'ing... we as adults think it's got to be uncomfortable, but the kids don't complain. And of course because we know rf'ing is so much safer, and there's been much more education about the comfort of kids legs, none of us worry about it. ;)

I would also think that holding the hips back as opposed to allowing some forward movement is a good thing, like Ulrike is saying. If the hips are moving further forward, then the shoulders are going to drop slightly in the harness - could that affect the risk of ejection or create a risk of the carseat straps/chest clip/crotch strap injuring the child?

My kids are still on the relatively young side, but as of yet I've seen nothing that would worry me in terms of squishing/uncomfortable crotch straps. I can also say I haven't seen anything that screams out of discomfort at seat checks either... so I guess take that as the anecdote that it is, but I really don't worry about it. :shrug-shoulders:
 

Patriot201

Car-Seat.org Ambassador
One other thing of interest, is that the Radian specifically instructs parents to choose the crotch strap position right at, or just under the child - and to never use a position forward of the child. Must be some reason for that?


I didn't realize that SKJP states that for the Radian. :cool:

I was *just about* to post something saying that we should have recommendations similar to the harness height "recommendations"
(at or below the child or at or beyond the child, depending on RF/FF or whatever the crash tests reflect is best).


I have always preferred the crotch strap to be just at the child, but that is only because I find it easier to buckle. I hate it when it is under the child merely because I find it harder to buckle.
However, if it is safer for it to be under the child, I will suck it up and deal with my own issues with buckling. :p

I don't have a choice about crotch buckle position in the Boulevard, so I already have to "deal" with having to dig it out from under bigger kids. In the Scenera, I moved the crotch strap out so that it is just barely beyond the child. If it is safer for it to be under the child, though, I will move it back. :)
 
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csma

New member
My DD is well within the size guidelines for the Regent (3yrs., 41#, 32lbs.) and has enough room in the closest setting for the crotch strap for me to slip most of my hand between her and the strap. She could wiggle her hips/butt forward, which then made the harness too loose to pass the pinch test. Also, would the movement of her hips in an actual accident leave her vulnerable to internal injury in her lower abdomen? I am really glad to see that the Frontier was reported as having a much smaller closest setting, as it would fit her much better. Maybe there is a safety benefit???
 

joolsplus3

Admin - CPS Technician
Thanks for mentioning that Trudy. The manual with pictures of that can even be seen at www.skjp.com.

Yeah, it seems to be a group hysteria phenomenon lately (not to discount those with the truly uncomfortable kids, but it's suddenly a big deal where it used to be rarely even mentioned or noticed to be a problem). It used to be the very rare, very large 4 yo boy that was genuinely uncomfortable in a Marathon, and now everyone's upset that even the Nautilus doesn't have enough room (doesn't it have an inch more room?)...and possibly Dorel played a part in this, with their SHORT Apex strap...it wasn't about crotch room, but the short strap making legs getting pinched... it brought even more attention to that region, IMO.
 

arly1983

New member
In that case, I am glad J's regent went to a new home. He is such a stringbean in even a cloth diaper, he easily had 2 inches.
The nautilus, I don't understand either, he is still in the second from the front slot. and that crotch strap is plenty long.
The EFTA has a ton of room. Both kids are right before the inner most setting.
 

ProudMomof5

New member
hmm... I did not know any of this. I am pretty sure I have the crotch buckle too far from my dd in her scenera. argh.. there is just so much to learn.
 

mish

New member
With infant seats, don't we tell parents to roll up a washcloth and put it between the baby and the crotch strap if it is too far away? That tells me that it needs to be right up against them. I understand that they slide down more in infant seats, but we don't want them to slide forward before a crash in an upright seat either. My 4 year old is right up against the crotch strap in his Nautilus and he seems comfortable. I even asked him the other day and he said it doesn't hurt.
 

southpawboston

New member
With infant seats, don't we tell parents to roll up a washcloth and put it between the baby and the crotch strap if it is too far away? That tells me that it needs to be right up against them.

i would think that this is not even an issue with RF seats (in a frontal crash), since most of the crash force is going to be exerted up at the shoulders. the infant's body will move away from the crotch strap, instead of towards it.
 

fyrfightermomma

New member
It'd be interesting to see where exactly on racecar drivers it is positioned. If its right next to the body, under a little, or in front of a little. They do tons of research so it would be very interesting to see where they consider "safest" (although I know full grown adults and children are different) Anyone married to a racecar driver??? ;)
 

keri1292

Well-known member
i would think that this is not even an issue with RF seats (in a frontal crash), since most of the crash force is going to be exerted up at the shoulders. the infant's body will move away from the crotch strap, instead of towards it.

:yeahthat:
I think the washcloth is great for keeping those little legs on each side of the crotch strap. A tiny newborn can pull them up in the fetal position and get two legs on one side. :eek:
My boys have no issue with the MA buckle at 3 and 4. Dd will probably never use the 2nd buckle slot for the Regent. She's just way too skinny.
 

mish

New member
I thought we put the washcloth there so they didn't slide down before a crash to where their shoulders were below the harness. I am talking about really tiny babies, by the way. This is what I was taught in my tech class (which I have found out a lot of stuff they told was wrong!!!). Anyway, if I have been doing this wrong, please let me know. I would never want to give out bad information.
 

UlrikeDG

Admin - CPS Technician Emeritus
I thought we put the washcloth there so they didn't slide down before a crash to where their shoulders were below the harness. I am talking about really tiny babies, by the way. This is what I was taught in my tech class...

This is my understanding, as well. :)
 

Yoshi

New member
Speaking strictly about the comfort issue, here- since I know nothing of the crash dynamics and I am not a tech- but we have owned:
Regent
DC
Apex
Radian
EFTA
Nautilus
Only the DC, Apex, and Radian had "short" crotch buckle depths and were close to or under my DD. She hated the DC and the Apex and would yell and whine about how uncomfortable it was constantly. For some reason the Radian never bothered her. I don't think it is fair to conclude that some parents are necessarily "projecting" their own thoughts about what might be uncomfortable on to their child. Maybe you all just have easy-going or very petite kids. Some children are more vocal, more sensitive, more picky, you name it. I have that kid. I NEVER ask her if she is comfortable, because I don't want to plant any seeds of doubt in her mind. She tells me if she is. I think the MA, DC and BV are proportioned all wrong for older children anyway, since not only does the crotch area get tight, but so does the shoulder area. They are great for infants up to age 3 or so. Safety comes first, of course, and perhaps crotch buckles should come in more than 1 or 2 slots to ensure a more customized fit? Kind of like the infinite adjust idea.....then it would always be in the correct spot.
 

Mama!

New member
My dd is right at the slot on the Regent. I assume its the closest one? Its however it was shipped to me.
 

snowbird25ca

Moderator - CPST Instructor
In the Scenera, I moved the crotch strap out so that it is just barely beyond the child. If it is safer for it to be under the child, though, I will move it back. :)

I believe Cosco states crotch buckle position closest to the child. I'm not sure if that's they're wording with every single seat though, and I've only seen 1 scenera and they didn't have the manual...

With infant seats, don't we tell parents to roll up a washcloth and put it between the baby and the crotch strap if it is too far away? That tells me that it needs to be right up against them. I understand that they slide down more in infant seats, but we don't want them to slide forward before a crash in an upright seat either.

We were told the wash cloth positioning was to help the harness fit better, and in the case of 3pt harness to make sure they're legs didn't end up on the same side of the buckle due to wiggling if their crotch was far back from the buckle.

It'd be interesting to see where exactly on racecar drivers it is positioned. If its right next to the body, under a little, or in front of a little. They do tons of research so it would be very interesting to see where they consider "safest" (although I know full grown adults and children are different) Anyone married to a racecar driver??? ;)

AZgirl's dh is a racecar driver. ;)
 

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