Taking bikes on buses in Spain, yes and no.

dohouch

Busses are always cheaper than trains in Spain, go to more places, often more directly, and importantly if you don't want to waste the sun-shine they travel at night.

Now can you take your bike on the bus? Well I haven't yet, but here's my experience. I asked at 2 bus station ticket offices, and the anwer was NO.

But in a hostel in Granada, Oasis hostel ( best ever!) got talking to a girl who had just arrived from Seville, had a new bike,bought in Seville asked how she got it to Granada, she said on the BUS.
I then inquired at Granada bus station if I could put my bike on the bus up to Jaen, a Sunday day trip, was told NO. The following day at the same bus station, travelling to Malaga, I see this guy standing there with his bike, and sure enough he sticks on the bus.

So don't ask, just wheel your bike up to the bus and slide into the luggage underneath. Yes there are are various bus companies, I think my queries were to ALSA, which I think is the biggest company. So give it a go.

blorg

Policy completely depends on the individual bus company, and as you say implementation will depend on the individual circumstances.

Some bus companies will officially take bikes although sometimes they demand that the bike be wrapped to prevent dirtying other people's luggage. I took a bike from Santiago to the north-east corner of Galicia OK (of course would likely be more common to have people with bikes in Santiago.) I seem to recall it was an option from San Sebastian also, although they required wrapping and we ended up steeling ourselves for the inevitable fight with the conductor and got the night train back to Madrid instead.

Sean02

Never had a refusal Bilbao airport bus even allow you wheel the bike on board no charge. Then on to Miranda I think the charge was €12 for the bike.