Can I still use a child seat on my luggage back ?

YES.

If it works without the Teebike wheel, it can also work with it! The wheel doesn't change geometry or security of your bike. Nonetheless, it is very important that you check the function of your brakes on a regular basis.

The total weight carried by the bike must not exceed 150kg / 330 lbs.

Good to know Just like for any electric bicycle, the wheel's autonomy will vary according to the weight carried and the level of electric assistance chosen. With a child seat on the bike, it will therefore be less powerful.