Seatbelt deficient

The seat is in order, the construction on the seat tube incl. The support is well thought out and practical, even on bumpy tracks to keep the blows to the seat is limited. The adjustable backrest can not be used - the angle is too small to be truly practical.
A real lack is the seat: It is designed as a three-point belt not, the two loops are fixed in common between the child's legs.

By the missing link in the chest area, the child can simply strip the belt from the side!

It does not matter how firmly you do the belt, after a while my son has exempted (18 months). I have first resorted so that I have tied the protruding end of Gurtbandbandes. Unfortunately, this is also not a solution: The tape is coated and therefore a bit slippery, after some time the small passenger therefore gets it himself aufgefummelt.
I have now made the chest of an old backpack on the belt (standard 1 inch ribbon), so it is now.

The seat is a whole really good and obviously the best thing there is to child seats for bikes - the thing with the belt tarnishes this but nevertheless significantly, therefore only 3 stars.