How long to harness?


CPSDarren - Admin
Staff member
I don't think head loads are something to completely ignore.

Definitely not to be ignored, though head excursion related contact injuries are usually considered to be the greatest concern. Either way, proper installation and use are the best prevention for both!
I agree with Darren. It really is difficult to know without proper data.

K is a major car sleeper so he will be harnessed in his FR and PN for some time. L (greatly) prefers a harness over any booster. She's 8.5. I think it is very situation-dependent. Got a wiggly kid? Car sleeper? Child who is likely to misuse a booster? Harness, if at all possible. Child who will properly use a booster at all times and is over 5 (ideally)? Booster it is.


Well-known member
I fall down on the side of harnessing as long as you reasonably can, however I know I don't have data to back that up. A lot is based on my "gut feeling."

I also recognize the reality that there are a LOT of cases where harnessed seats are used improperly in situations where a booster may be more likely to be used correctly. Both installation and harnessing are challenging for some families and even more so sometimes for babysitters or grandparents. So I am cautious in advising other families to harness as long as they can. I fear that sometimes this advice may lead to more mis-use in some situations, including using outgrown harnessed seats and entrusting untrained caregivers (such as grandparents) with the use of a harnessed seat where a booster would be simpler to explain and more likely to be done correctly.

I have a hypothesis that the reason we don't see much data proving harnesses or boosters are safer for kids in the grade school age groups is because the mis-use rate is so high for both types of seats. That makes it very hard to come up with any reliable data.

Personally, I am not even remotely convinced that neck loads are a compelling reason to move to boosters. There are so many trade-offs it's impossible to pull out one of many potential injuries and say THIS is the one we are most concerned about and need to worry about more than anything else. Head excursion, submarining, chance fractures... these are ALL concerns and which seat protects best against which one mostly has to do with proper use of either type of restraint but also has a lot to do with dumb luck and which direction you're hit at and where the impact lands and how severe it is... all factors that cannot be predicted or controlled.

Now, it's easy for me to say I'll harness "as long as possible" because I kinda suspect my daughter will be too big to harness in the Frontier by her 6th birthday. :/


New member
I don't have anything to contribute, just more questions.
What about things like pre-tensioners [removes all slack from the seatbelt in the event of crash, right?] and load limiters that seatbelts [may] have? My understanding is that not all cars have those in rows other than the front one; but if there are, then how do these interact with harnessed seats, if at all [being from Europe I of course think ERL belts first]; and do these improve outcome with a booster?
My DD turns 5 in a month, and as soon as her baby brother needs her rear-facing seat [Britax MaxWay], which is bound to happen in a few months, I'll switch her over to a booster. She weights 19kg and therefore is over the common FF harness limit of 18kg here in Europe and I'm not getting the TWE.
My understanding is that here in Europe the plan for future is sort of that if it's FF harnessed seat, then it's installed with rigid isofix to eliminate misuse of at least the installation part. Currently isofix limits FF harness to 18kg, but with ISize there will probably be seats that allow at least few more kgs.

Did some googling while I typed this, and found a study on boosters/integrated boosters and load limiters and pre-tensioners. Seems that at least on the test sleds load limiters/pretensioners do help with a booster.

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