Hello FilBones
For this route, bike reservations are only mandatory on FRI, SAT, and SUN days, not on THU days. This is why the bike reservation option is not given. IC2, IC5, and IC51 are the only trains that need bike reservation on all days during summer. On other trains, bikes can be taken along if space is available, there is no transportation guarantee, also not that you hold a bike ticket; you must follow the instruction by the train staff.
You can take your bike along provided there is a bike space left; it is first come, first served. See the monitors on the platform to identify the coaches that offer bike spaces (bike icon).
Kind regards,
Roland