If you travel with your bikes in bags, such as TranZ bag, you do not need a ticket and the chance that your bicycle will be transported is higher than when you travel with your bikes assembled, as they are. In the latter case, you need a reservation for your bikes on most IC trains, especially on weekends from Fri-Sun. Without reservation, there is no transport. In certain trains and public transport services, the transport of bicycles is may be allowed, may be restricted, or impossible.
There is good advice on this website: Travelling with bicycles | SBB