Depends on the bus. There's local buses in towns that have zero space for bikes but there's the longer distance/intercity type buses run by companies like Sagales, Aviva and others that will happily take a complete bike (if there's space and that's probably at a premium in summer, especially if you're anywhere near a coast)
As for trains, the slower Media Distancia and Regionale will take complete bikes (that's how I got to the start of Transiberica the last time) but if you want to use the various fast trains you need to have bikes boxed/bagged/covered and they generally want them in the storage areas which differ per train.
This guy talks about Bromptons on the fast trains...
Depends on the bus. There's local buses in towns that have zero space for bikes but there's the longer distance/intercity type buses run by companies like Sagales, Aviva and others that will happily take a complete bike (if there's space and that's probably at a premium in summer, especially if you're anywhere near a coast)
https://www.arriva.es/en
https://www.sagales.com/en
https://www.alsa.com/en/web/bus/home
As for trains, the slower Media Distancia and Regionale will take complete bikes (that's how I got to the start of Transiberica the last time) but if you want to use the various fast trains you need to have bikes boxed/bagged/covered and they generally want them in the storage areas which differ per train.
This guy talks about Bromptons on the fast trains...
https://www.youtube.com/watch?v=lhmvI_AwxxQ