http://www.ibike.org has a very nice compilation, reasonably up-to-date, of which airlines charge how much, etc.
see: http://www.ibike.org/
Their caveat is YMMV, of course, as it sometimes depends on who you get for a gate agent at baggage checki-in. Also, while some sites suggest calling the stuff 'camping gear' or other hedges, some airlines charge for 'sports equipment' no matter what type. Of course, if you lie and airport security staff discover the deception it may be more expensive in other ways. :-/ .
Bob Hillery Stratham, New Hampshire usa
commuting today on a nice Peugeot UO-8