Hello loiseman14
Thank you for your question.
Bike are allowed as hand luggage, only if it can be placed in the compartments provided for hand luggage. Normally, only folding bicycles meet this condition.
For your “normal” bike you need a separate ticket and a reservation. Tickets and reservations for bikes are not available online. You can buy them by phone (+41 51 225 78 00) or directly at the train station.
I wish you a nice weekend.
Kind regards
GiorgiaB