reservation on trenitalia connection

Seat61 has some advice for travel with a bike.

https://www.seat61.com/bike-by-train.htm#Italy

In Italy, you can take it on some Intercity trains for €5 supplement. IC641 seems to be OK. I don’t know how buy the reservation. You may need to call Trenitalia or ask at Milano

In Switzerland, you can buy a bike ticket for the day for 15 CHF online from SBB. I don’t know if that covers you on the EC, but it does accept bikes, if you look in the SBB timetable. Again, you might need to check with SBB.

I tried hotline from Trenitalia (German option 3) without success. After > 30 minutes hold the line music ended. 😕

I tried German db hotline with in total 5 service employees. Every time they realized that this will be not easy they hang up without any warning. I assume that there calls will be measured in seconds so nobody wants to do difficult long duration calls. 😕

After that I went to the local train station and the service employee managed it - after calling some internal support. The planned connection was not possible. They did not get an error message so they assume, that there’s no bike place available. So we changed the trains (same day) - with success. 😄

So next week we will give it a try for going back from France to Germany. 😱

In Switzerland, buying a bicycle ticket/reservation to Italy is currently not possible at all:

https://www.sbb.ch/de/reiseinformationen/individuelle-beduerfnisse/reisen-mit-velos/nach-europa.html

DB may be able to book a bicycle reservation for the EC (not online though):

AFAIK buying a bike reservation in Italy for a journey on a pass is not possible online. DB cannot book bicycle reservations for domestic trains in Italy, so there the only possibility is a Trenitalia ticket office or by phone:

You can check availability for bikes online on the Trenitalia website by starting a normal booking and then checking whether you can add a bike. I can't add a bike to EC153. IC641 still has space, the later IC 675 too.

For further advice, it would be very useful to know from where exactly you are starting and which train you were planning to take to get to Switzerland.