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  1. #1
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    Planning ahead for the switch to FFing

    Okay, before anyone freaks out - NO, I am *not* planning on turning my 19-month-old DS FFing any time soon. However, after reading through some of the threads about people with wee peanuts who can RF till kindergarten, it's reminded me that we will not have that luxury, and I'm a planner so I like to figure things out well in advance.

    If DS stays on his weight curve, I predict him hitting 35 lbs around 26 months old, give or take. Which is better than I'd hoped for - I was afraid we wouldn't get much past 18 months, but his weight slowed down for a while there - but still quite young from a spinal maturity standpoint. Which brings me to a couple of questions:

    - For a "just turned two"-year-old, how close would you go to the weight limit? My inclination is to weigh weekly as he gets close and turn when he's consistently crossing the 34-lb mark.

    - Is there a consensus opinion on the suitability of the TF for young-ish FF'ers? It will be tethered when we go FFing, obviously (we're in Canada, it's the law). It's already our second convertible, since we replaced our MA when DS was closing in on the MA's 30-lb RF limit, and I hope it'll be our last seat for a while, since DS is really comfy in the TF.
    Lori, mum to:
    Duncan (July 6/07): 43.5", 42lbs, FFing in a True Fit

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  3. #2
    CPS Technician Pixels's Avatar
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    Re: Planning ahead for the switch to FFing

    For a child right at 2 years old, I'd weigh constantly, and not turn until he's over 35 pounds nekkid 50% of the time.

    I know most people on this board recommend counting clothing, shoes, etc in the weight. I don't, because FMVSS 213 doesn't. They use a dummy that's a certain weight, and on top of that is wearing certain clothes. Also, I know that the seat won't perform perfectly at 34.9 pounds and fail spectacularly at 35.1 pounds. Those factors combined, plus the huge safety increase in being RFing at that age, I would be more willing to push those limits.

    For an older child, I wouldn't push it so hard, and would be more inclined to turn at 34 pounds.
    Melissa, CPST and Mom to three

  4. #3
    CPS Technician Splash's Avatar
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    Re: Planning ahead for the switch to FFing

    I think the seat you have is awesome all around and fine for FF. The biggest RF safety benefit is in side impacts, there really isn't as much in frontal impact difference as you would expect.

    I'd weigh him once in awhile once he hits 34 pounds or so, but I wouldn't be terrified of him being 36 and still in that seat. Once you realize he's over 35 pounds, turn him. But don't make yourself insane over a few ounces. As pixels said, it's not going to fail catastrophically at 35.5 pounds. The biggest "failure" in a RF seat is over-rotation. The front seat will largely prevent that and even if it didn't, the TF has a spectacularly tall shell and the chance that a properly buckled toddler ramping out of it is very slim.

    Once you turn it, it'll be awesome. I loooove that seat more than any other seat ever. Too bad I returned both of mine.
    I'm glad you're a safe driver. I'm eating cereal and applying mascara using my rear view mirror while playing bejeweled on my iPhone. And I'm driving right behind you. 
    You're only as safe as the most dangerous driver on the road. Buckle accordingly.  

  5. #4
    CPS Fanatic zeo2ski's Avatar
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    Re: Planning ahead for the switch to FFing

    I agree with the others. I would not turn him at 34 lbs, wait til the full 35--it could be months more! And there is always hope that he might switch growth curves a bit now that he'll be running around. Also, take off his shoes in the car once he gets up there in weight and you'll gain a little. And as long as your CR and vehicle allow it, I'd brace the CR against the front seat once he's getting close to the limit if you're nervous about it.
    Cathy
    B-- 6.5y harnessed cowmoo FR85;
    Sl--5y RF RXT;
    H-- 2.5 RF RNXT;M--7mos CCOA--1 mos KF30 and R 1.5 RXT

  6. #5
    Moderator - CPSTI Emeritus Defrost's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by pixels99 View Post
    I know most people on this board recommend counting clothing, shoes, etc in the weight. I don't, because FMVSS 213 doesn't. They use a dummy that's a certain weight, and on top of that is wearing certain clothes. Also, I know that the seat won't perform perfectly at 34.9 pounds and fail spectacularly at 35.1 pounds. Those factors combined, plus the huge safety increase in being RFing at that age, I would be more willing to push those limits.
    Actually, there is at least one carseat that was shown to fail spectacularly at barely over the limit for speed during a crash test. You have to factor in both weight AND the speed of the vehicle at the time of the crash in order to get the crash forces. A seat might not fail spectacularly with a 36lb child in it at 25mph, but it might at 30mph.

    What we KNOW absolutely is that the seat WILL perform when used correctly. Pushing those guidelines is never "best practice."
    Debbie, CPST-I
    driving my '07 Mazda5 with
    Thomas (18) * Sam (17) * Patrick (15) * Macha (13)
    Safely secured with seat belts - everyone, every ride!

  7. #6
    CPS Technician Pixels's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by Defrost View Post
    Actually, there is at least one carseat that was shown to fail spectacularly at barely over the limit for speed during a crash test. You have to factor in both weight AND the speed of the vehicle at the time of the crash in order to get the crash forces. A seat might not fail spectacularly with a 36lb child in it at 25mph, but it might at 30mph.

    What we KNOW absolutely is that the seat WILL perform when used correctly. Pushing those guidelines is never "best practice."
    All we know is that the seat WILL perform under crash-test conditions. This means the exact test bench, carseat attached to precisely those standards, harness adjusted just so, perfectly frontal impact at 30 mph. We don't know about any other conditions, such as 35 mph, or anything other than a perfectly frontal impact. We don't even know for sure about installs in real-life vehicles, which have seats that are different than the test bench, and actually have front seats.

    You can't prepare for every eventuality. Of course you wouldn't recommend not driving over 30 mph, that's just not reasonable. Yet that is the speed at which restraints are tested, and deemed "safe" or "not safe" based on passing the tests. I don't see much difference between pushing the limit on occupant weight vs. the limit on speed.

    I'm not advocating going over the weight limit in any case.
    Melissa, CPST and Mom to three

  8. #7
    Moderator - CPSTI Emeritus Defrost's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by pixels99 View Post
    All we know is that the seat WILL perform under crash-test conditions. This means the exact test bench, carseat attached to precisely those standards, harness adjusted just so, perfectly frontal impact at 30 mph. We don't know about any other conditions, such as 35 mph, or anything other than a perfectly frontal impact. We don't even know for sure about installs in real-life vehicles, which have seats that are different than the test bench, and actually have front seats.
    Well, we do know a bit more than that. We know that crash-tests do simulate real crashes in a way that help us make important decisions for preparing for real-life crashes, because of post-crash evaluations. It has been clearly shown that carseats and restraints that meet federal guidelines DO save lives and prevent injuries when used properly.

    You can't prepare for every eventuality. Of course you wouldn't recommend not driving over 30 mph, that's just not reasonable. Yet that is the speed at which restraints are tested, and deemed "safe" or "not safe" based on passing the tests. I don't see much difference between pushing the limit on occupant weight vs. the limit on speed.
    This was not the point of my argument. Pushing the weight limit is very different than pushing the speed limit PRECISELY because of the fact you stated above - crash tests are different than real-life crashes. They put such weight limits on carseats BECAUSE of those differences, not because someone pulled a magic number out of the air and said "35's good, let's use that." A 30mph crash-test does NOT simulate a 30mph crash - it does not take into account braking or any force absorption provided by the vehicle's frame, or skidding, etc. It is important to follow the limits on carseats because of the fact that you can't pick what type of crash you get into.

    I'm not advocating going over the weight limit in any case.
    I'm sorry - then what exactly did you mean by this?

    Quote Originally Posted by pixels99 View Post
    For a child right at 2 years old, I'd weigh constantly, and not turn until he's over 35 pounds nekkid 50% of the time.
    Wouldn't that mean that for up to half the time the child would be over the weight limit?

    To the OP: I think your plan is fine - to weigh weekly when he gets close and then turn him when he's consistently above the 34lb mark.
    Debbie, CPST-I
    driving my '07 Mazda5 with
    Thomas (18) * Sam (17) * Patrick (15) * Macha (13)
    Safely secured with seat belts - everyone, every ride!

  9. #8
    Moderator - CPS Technician safeinthecar's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by Defrost View Post
    Actually, there is at least one carseat that was shown to fail spectacularly at barely over the limit for speed during a crash test. You have to factor in both weight AND the speed of the vehicle at the time of the crash in order to get the crash forces. A seat might not fail spectacularly with a 36lb child in it at 25mph, but it might at 30mph.

    What we KNOW absolutely is that the seat WILL perform when used correctly. Pushing those guidelines is never "best practice."
    But what is the difference here between a seat that might fail at 36# and 30mph, and a 34# child going 35mph, or a 25# child going 60mph. Following this logic, car seats need speed limits as well as weight limits.
    Kimberly
    Proud mommy of Becky 18! Danny 15 Hope 12~Auntie to William-14, David-10, and Logan 2~

  10. #9
    CPS Technician Splash's Avatar
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    Re: Planning ahead for the switch to FFing

    Well, car seats are not an exact science. There is, of course, some measure of guess work involved, along with a smidge of pure dumb luck and prayer.
    A 30 mph crash test is an absurd crash. It is near unsurvivable, regardless of restraint used. It represents the top badness level of the vast majority of crashes. Yes, there could be a worse crash than that, but it's unlikely that anyone would survive it, carseat or no. In that respect, it's safe to assume that the seat will perform as indicated in almost all situations, and the situations in which it would not perform as promised are ones where seat failure is a secondary concern, because the child will likely be dead anyway from the sheer force of the crash.

    A 30 mph sled test is not like driving 30 mph and hitting something. It's more like driving 60 mph into a brick wall without letting up on the gas at all. That's why there was just huge stink over CR bunking the crash results a few years ago... they simulated crash conditions that, in the real world, would have most certainly killed everyone on impact regardless of restraint.

    I would not religiously weigh a child every day to see when they hit "the limit." Nor would I turn them well before the limit at that age. But as soon as it tipped over 35, I'd flip. Is there a margin for error? Of course there is, that's why I wouldn't be concerned about a few ounces before I caught it. But I don't know how big that margin of error is. 3 pounds? 5? 7? 13? I'm gonna rely on the MOE to let me slide until I weigh him and realize he's 35 lbs 5 oz, but I'm not gonna depend on it to carry me to 39 pounds because I "think" it can handle it.
    I'm glad you're a safe driver. I'm eating cereal and applying mascara using my rear view mirror while playing bejeweled on my iPhone. And I'm driving right behind you. 
    You're only as safe as the most dangerous driver on the road. Buckle accordingly.  

  11. #10
    Moderator - CPSTI Emeritus Defrost's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by safeinthecar View Post
    But what is the difference here between a seat that might fail at 36# and 30mph, and a 34# child going 35mph, or a 25# child going 60mph. Following this logic, car seats need speed limits as well as weight limits.
    Splash already explained it pretty well, so I'll just add that crash tests aren't done to simulate a crash, they're done to simulate crash FORCES. They aren't trying to determine how a carseat will perform in a certain type of crash, they're trying to determine how it will perform when exposed to a certain amount of crash FORCES. Does that make sense?
    Debbie, CPST-I
    driving my '07 Mazda5 with
    Thomas (18) * Sam (17) * Patrick (15) * Macha (13)
    Safely secured with seat belts - everyone, every ride!

  12. #11
    CPS Technician Pixels's Avatar
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    Re: Planning ahead for the switch to FFing

    I'm not advocating going over the weight limit in any case.
    I'm sorry - then what exactly did you mean by this?
    For a child right at 2 years old, I'd weigh constantly, and not turn until he's over 35 pounds nekkid 50% of the time.
    Well, it means that I worded the first statement poorly. I meant that I'm not advocating ignoring the weight limit, and leaving the child RFing to 38 pounds. But I'm also not going to reinstall the carseat every time his weight changes by an ounce or two up or down, and because of his age, I want him RFing as long as possible.

    I really think that safeinthecar and Spash explained my argument better than I could. Sometimes I'm just not very good at getting my ideas into words.
    Melissa, CPST and Mom to three

  13. #12
    CPS Technician Pixels's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by Splash View Post
    A 30 mph sled test is not like driving 30 mph and hitting something. It's more like driving 60 mph into a brick wall without letting up on the gas at all.
    Wouldn't it be like driving 30 mph into a brick wall? I'm not understanding how the speed would be doubled.
    Melissa, CPST and Mom to three

  14. #13
    Moderator - CPSTI Emeritus Defrost's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by pixels99 View Post
    Wouldn't it be like driving 30 mph into a brick wall? I'm not understanding how the speed would be doubled.
    It's not about the speed, it's about the force. Driving 60mph into a concrete wall creates different forces than driving 60mph into another car. Your speed is the same, but the forces are different.

    The 30mph sled test actually mimics the force of two vehicles driving 30mph and hitting each other head-on without either one hitting the brakes (which is a highly unusual and very severe type of crash, of course). The forces in that case are equivalent to driving head-on into a concrete wall at 60mph.
    Debbie, CPST-I
    driving my '07 Mazda5 with
    Thomas (18) * Sam (17) * Patrick (15) * Macha (13)
    Safely secured with seat belts - everyone, every ride!

  15. #14
    Moderator - CPS Technician safeinthecar's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by Defrost View Post
    It's not about the speed, it's about the force. Driving 60mph into a concrete wall creates different forces than driving 60mph into another car. Your speed is the same, but the forces are different.

    The 30mph sled test actually mimics the force of two vehicles driving 30mph and hitting each other head-on without either one hitting the brakes (which is a highly unusual and very severe type of crash, of course). The forces in that case are equivalent to driving head-on into a concrete wall at 60mph.

    Add to this that upping the speed of the 30mph test to 35mph is a 1/6th increase. Since the 30mph test actually simulates 60mph into a wall, a 35mph test (1/6 increase) translates to the equivalent of 70mph (1/6 increase) into a wall. 70mph head on into a wall is not a crash that happens all that often.

    Honestly, warning parents to worry about the weight of clothing, shoes, a big meal, a full diaper, and 13 contraband matchbox cars hidden in various parts of a little boys clothing (I kid, I kid) is putting too fine a point on it. Most parents are not nearly as passionate about car safety as we are and when we make it too complex, we lose their interest. K.I.S.S.
    Kimberly
    Proud mommy of Becky 18! Danny 15 Hope 12~Auntie to William-14, David-10, and Logan 2~

  16. #15
    Moderator - CPSTI Emeritus Defrost's Avatar
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    Re: Planning ahead for the switch to FFing

    Quote Originally Posted by safeinthecar View Post
    Honestly, warning parents to worry about the weight of clothing, shoes, a big meal, a full diaper, and 13 contraband matchbox cars hidden in various parts of a little boys clothing (I kid, I kid) is putting too fine a point on it. Most parents are not nearly as passionate about car safety as we are and when we make it too complex, we lose their interest. K.I.S.S.
    I do agree on that - but I'm also concerned with any recommendation to knowingly "push" the manufacturer's stated limits.
    Debbie, CPST-I
    driving my '07 Mazda5 with
    Thomas (18) * Sam (17) * Patrick (15) * Macha (13)
    Safely secured with seat belts - everyone, every ride!

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