Can I bring my bike on the train?

The question was:

Planning the 2018 Camino by bike. Two of us need to get from Madrid to Leon with our bikes on the train. We will again need to get our bikes on a train from Santiago to Madrid.
We would MUCH prefer if we did NOT have to dismantle the bikes. From what I can tell, bikes are allowed on SOME trains etc. 
Can anyone offer some advice? Has anyone done this??

Read all the advice on the forum on bringing a bike on the train in Spain.