I live in the Netherlands, where everything in done by bike. It's reasonably common to see people biking with babies in the Björn, but it's really not safe. If you fall or stop short and go forward against your handlebars, the baby gets squashed. And it seems like a good way to get whiplash since the baby is facing in.
We solved this problem by getting a bakfiets
and putting our car seat in it. Since you're in Belgium, this would be a feasible option for you, too.
Another option would be to get a car seat frame for your bike. It's a wire frame that mounts onto the back of your bike and the infant car seat snaps right in. I don't have a link for this, but if you're interested in this option and don't know what I mean, just let me know and I'll help you. They are readily available here and aren't expensive. It's just a light wire thing. The only reason we didn't do this was that the bakfiets is safer, since the baby has the added protection of the bak, and we intend to have more kids so it will be useful for us for transport of multiple children in the future.