I flew Ryanair to Girona last September with my wife, for a cycling tour in Languedoc. They charged £15 each way for each of our two bikes (total £60) which added quite a lot to the 'cheap' airfares...
When we arrived at Prestwick we were asked to wheel the bikes through a side-door where a guy tagged them with a 'fragile' label and wheeled them off.
(Maybe I'm just being naive but I got a reasuring feeling that the bikes were not going to be chucked around like suitcases, as I know they are when you fly BA etc who don't charge extra.)