OCD CycloClimbing is most well-established english language club for people enjoying cycling on mountain roads.
The name of my site come from OCDs use of this term (which they have done for 33 years now).
From What is OCD Cycloclimbing:
OCD stands for Ordre des Cols Durs – the club of the hard cols – a French cycle club of which we are the British-based English language equivalent. OCD Cycloclimbing acts mainly as an information exchange for cyclists who enjoy cycling in the mountains. If they wish, Members can claim pass heights each year and progress through grades of membership. Otherwise they can simply enjoy the magazine and the e-group. Members are of course encouraged to contribute to the magazines and pass guides.
(The French club has its base in the south of France, but have no web presence.)
CLUB des CENT COLS is the biggest mountaincycling club in the world and is French, but with smaller sections in other countries like Italy and Switzerland and with many other foreign members. The main memberbase is still French for this club founded back in 1972 in Annecy. The name means Club of the One Hundred Mountain Passes’ and describes the main rule for entry into the brotherhood – one has to climb at least 100 different mountain passes of which at least 5 must be higher than 2000m. One of the main resources of this club are the ever expanding and updated pass lists for different countries that are available for purchase. I have given reference numbers to these lists as far as possible in the pass descriptions in the pass lists on this website. They also offer free online overlays for easy location of passes found in their guides for France and (partly for) Switzerland. Mailing-list is in the French language.
Brevet International du Grimpeur (BIG) is the growing Belgian club started by Daniel Gobert which claims to be the most international one. For members of BIG both mountain tops and passes are allowed to be counted by the members from a predefined list of 1000 in gaining finer diplomas from the club. The main reason for the club as with the others is of course the exchange of knowledge and experience.