Switzerland has a railroad network that, in proportion to the size of the country, is one of the most dense in the world; wherever you go you will find a train or at the very least a streetcar or a cog railway.
Bike service is probably the most extensive in the world; in fact all trains, including the Eurocity and almost all individual cars can accommodate a bicycle. The service is so prevalent that unlike in other countries, such as Italy, Germany and Austria, a bike symbol is not used on schedules at train stations, but only a crossed-out bike symbol, meaning the train does not carry bikes, for the rare case where service is not provided. That situation seems to be very rare; in the Geneva-Cornavin train station I scrolled through the entire schedule without finding a single incidence. But since that symbol exists I have to assume that some trains, that do not carry bikes, exist in Switzerland!
In brief, this is a true paradise for lovers of this service, and all the more valuable in a country where mountains abound with very challenging climbs, which could make certain areas inaccessible for the average cycle-tourist.