Alberto1973
Note that if your bicycle remains in one piece, you need to get a ticket for it in Switzerland (Bike Day Pass for 15.-). If it’s however disassembled and carried in a specific bike travel bag, it is considered as personal luggage and travels for free.
Whether a bicycle (in one piece) is ok or not often also depends on the line in question or sometimes also on the time of the day. Therefore you’d need to check each connection and leg in detail in the online timetable for whatever bicycle related symbols.
E.g. on IC’s on the Gotthard line, bicycles require a mandatory reservation and are therefore maybe a less preferrable option. And on the Schöllenen Railway, the last leg of your journey to Andermatt (small narrow gauge cogwheel train in the gorge), the available space for bicycles is very limited. In the worst case - think of another group of bikers - you might have to wait in Göschenen for the following train.