Quite a lot of pre-fl octys don't have the top tether option fitted in the rear of the back seats (although I suspect the welded in luggage loop is more than adequate!), so theoretically you can't buy baby/child seat which uses a top tether.

 

So it's obvious it's designed to stop the top of the child seat propelling forward in a frontal impact, but how important actually are they? Many manufacturers don't use them on various models and rely solely on the ISOFIX, so without the top tether are they just adequate, not AS safe, or what?

Think the now designs of a solid child carseat with proper isofix locks would not need to be tightened with top tether .

In a frontal impact the seat would have the direction to follow like up and front simultaneously so this means the seat would also head to the top (roof).

By the moment seat is well fastened using the isofix locks down in the bottom back side means no problem to be unsecured or get moved.

Watch some euro n cap videos regarding and you'll see the behavior..

Don't forget seats that are fastened in with only a seat belt are still deemed safe, and that is mind boggling when you feel how much you can move one around compared to a solid isofix fixing.

 

When our daughter was out of her first baby seat and into her first forward facing seat which was a Britax, it said in the manual that for our Qashqai it required a top tether, but not for my Passat that I had at the time so presumably it was something to do with the shape of the seat rather than general safety as the seat was of a solid one piece construction anyway so it wasn't going to flex.

 

If you are using a belt to strap a car seat in then I think a top tether is necessary, if you are using Isofix, then I would check the manual and if it says its not necessary then I wouldn't use it.

 

Edited 24 November, 20187 yr by SuperbTWM

Isofix is a global standard for automobile safety for children - anything else apart from that has to do with the car manufacturer's (I.e. car's seats design or safety design).

Of course the kid to be sitting in the seat will have to be fastened with the belts in any way.

The isofix is the relevant...hooks that are coming from let's say the same chassis..

Isofix is only up to child weight of 18kg though.

 

And, if you can move a belt fixed seat around a lot, its not properly fitted... done properly they should be pretty much rock solid..

 

Think about it... isofix is good to 18kg, but a car belt is designed to protect an average "75kg +" adult, and thats whats hold you childs seat in place.

 

Watch the videos of isofix test failures... thats scary stuff..

 

As to top tether.. if the child seat is designed to use it, and it isnt, then its not going to meet the same level if restraint its guidelines specify (ie the size of child its suitable for). I could be wrong, but id not be surprised if the "top tether" is a way for seat manufacturers to boost the weight capacity of isofixed seats beyond the 18kg?

Though the OP was talking about children (assuming until 18-20 kg)....

Apart from that, there are categories as regarding childseats and there is category for weights over 18 kg.

So from the moment you place an "extra" seat ON the car's seat, it has to be solid fastened the best way in its position which I suppose is the isofix locks. This means like an adult sitting in his own car's seat which is solid.

Now as for the belts using to fasten the child IN the seat (which is placed/fastened on the car's seat), you can use car's seat belt OR there are still childseats with their own belts and I think this is the best possible combination.

When I had a €550 Recaro seat for my daughter and after for my son, it even had it's own incredible double belt bender which would eliminate the injury of the sensitive that child body.

No tethers - no extra belts...

I'm with what @mac11irl said.  Isofix does provided a decent fixing point but my britax duoplus still required a top tether so I bought it and used it.  Sure it maybe ok without it but it would not provide the same level of restraint in all the circumstances.

 

That said I used the luggage restraints as the anchorage because it was easier to fit and adjust and it seemed equally as strong as the anchorage recess in the back of the seat.  However, I accept I can not say for sure.....

Buying child seats seems to be a minefield, I have a Recaro young sport (non isofix) which is fixed by belt and has two modes - 5 point harness and where the child is held in by the belt.  When in harness mode the seat belt feeds through a special clamp which holds it absolutely rock solid in place.   My Father-in-law bought a cheapy similar style one which is supposed to be held in place by the belt too (with a 5 point for the child) but when it was done up you could literally move it almost over to the other side of the car - needless to say I told him to ditch it and he now uses the recaro whenever needed.

 

For my other older we've got an ISOFIX high-back booster type (another recaro - Monza 2) and it too is rock solid with just the lower isofix points, it doesn't need the top tether which my VRS doesn't have.