No. 1-4 of 4 Links
Bikes n Trikes Rally Club
Based in the West Midlands, UK and actively seeking new members.
Brothers of The Third Wheel
Organization dedicated to riders of three-wheeled motor-cycles (trikes) for the purpose of socializing and riding together.
Gold wing road riders association.
If you are in the process of gathering information on sidecars you are at a good starting point.