I once took a brompton abroad - ridden from the airport train station to terminals, then took some cardboard from a shop, wrapped it in a duct tape and ta-da that was my suitcase, with no extra charges.
But if you do buy the 'ticket' for bike separately, in your case, you can check-in the bike + 15kg of your usual suitcase.
If you consider 32kg + your carry-on luggage that you take on boards, that's wayy more than you need really.
I once took a brompton abroad - ridden from the airport train station to terminals, then took some cardboard from a shop, wrapped it in a duct tape and ta-da that was my suitcase, with no extra charges.
But if you do buy the 'ticket' for bike separately, in your case, you can check-in the bike + 15kg of your usual suitcase.
If you consider 32kg + your carry-on luggage that you take on boards, that's wayy more than you need really.