Hi, I'd like to ask if its possible to bring my dissasembled roadbike in a bag bike with the bus ...

Hi there!
Sounds like you are going to join the road race which will be held in the end of May?

You have 2 options.

1) You can't bring it inside of the bus (seat), but they will keep it in the trunk if it's packed in one.
But in this case, generally they don't allow only one luggage per person in the trunk, so you have to keep your other stuff with you.
If your other bag is too big for the luggage rack or to keep it under your seat, you should better to book one more seat next to you.
That costs you child's fare.

2)There is a space to keep something like yours or for the skies, and snowboards in the bus, but it's limited.
It is first-come-first-served basis, so if that space is already full, you can't take that bus unless you give up your other stuff.

They accept one luggage per person generally in the trunk in both cases.

Hope this can be your help and enjoy!