That black one looks to be articulated, though it might have a locking pin or centering spring that allows the rig to stand upright when stopped. Attaching at just the rear rack like that, it can't be solid enough to survive as a ridged rig. On a motorcycle, ridged sidecars usually attach at four points, two high and two low. On bicycles they need at least three attachment points and four is better though tricky to accomplish with no lower frame forward of the BB.
Last edited by kevbo; 02-10-12 at 03:55 PM.