the adapter firmly against the face of the wheel turning to fig7 9 the clamping force mechanism 118 consists generally of a left end 300 and a right end 302 linked by a spring biased floating bar and clamp assembly 304 the left end 300 is pivotally coupled to the pivot arm assembly 104 b adjacent to associated apex 104 x and the right end 302 is pivotally coupled to the pivot arm assembly 104 a adjacent to associated apex 104 x thereby defining a force coupling between each of the pivot arm assemblies 104 a and 104 b the clamping force mechanism 118 is actuated by lever knob 306 of the bar and clamp assembly 304 coupled to the right end 302 the knob 306 rotates a shaft assembly 308 which pulls a pawl 310 the pawl 310 binds onto a bar 312 coupling the left and right ends and pulls the bar 312 through a set stroke towards the right end 302 the opposite end of the bar is coupled to the left end 300 through a compression spring 314 which is compressed during the stroke movement of the bar 312 with a set spring rate on the compression spring 314 and a set stroke length for binding of the pawl 310 a consistent load is applied between left and right ends each time the knob 306 is rotated from an unlocked to locked position when the knob 306 is in the unlocked position as shown in fig7 9 the pawl 310 slides along the bar 312 and is generally biased towards the unlocked position by a compression spring 316 this allows the pivot arm assemblies 104 a and 104.