Michaelh: Weight, design, suspension and construction are all equally important. If you were to construct a sidecar out of "exotic" materials that are strong enough and if it is the proper size and design for the bike, you would still need to add ballast weight in order to make it safe. Weight is most important on right hand corners, where too light of a sidecar will cause it to lift easily and without warning. An undersized suspension (and too small a tire) will cause the an overload of the sidecar suspension/tire and loss of control in a left hand corner. A weak, improperly located or undersized mounting system can "hinge" or break in a corner. Improper alignment and placing of the sidecar can cause serious handling issues, sometimes to the point of making it unrideable. This last point is common with Velorex "universal mount systems", especially on installs where the bike is too large and too heavy.
Lloyd, you are correct with the rule of thumb for sidecar weight and yes, it is for safe handling. Your Gold Wing/Hannigan GTL is a good example of proper bike to sidecar proportioning. I'm in the process of installing a GTL onto a '10 Wing and I'm really looking forward to the test drive! And regardless of the total weight, I'll still be using 50lb of sandbag ballast in the chair.
One thing I wish would go away this so called "rule" of 1/3 weight. This is a stupid rule. To many variables, how wide is the sidecar, where is the weight in the sidecar? How high up does the bike carry its weight? How heavy is the rider on the bike? How experienced is the rider? New riders I tell to add ballast until they have more saddle time and then remove some or all of the ballast over time as they have more seat time. All these things and many more contribute to how heavy the sidecar must be. 1/3 seldom works out and should not be used.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
