has a handle 138 handle 138 has fixably connected thereto a shoulder 140 projecting from shoulder 140 is an elongated shaft 142 having spring loaded retention balls 144 a coil spring 148 encircles shaft 142 and is seated against shoulder 140 to install a rear wheel 82 to the folding wheelchair 7 shaft 142 of the quick release pin 136 is inserted into coil spring 148 the remainder of shaft 142 is then inserted into wheel hub 134 and is inserted through the pin mount 135 until the retainer balls 144 re emerge on the extreme inboard side of the pin mount 135 before insertion through the pin mount 135 the pin shaft 142 is passed through a thrust bearing member or washer 150 shown only in fig1 to remove rear wheel 82 from the folding wheelchair 7 quick release pin 136 is simply grabbed by its handle and pulled with such a force that retention balls 144 are urged inwardly to allow the quick release pin 136 to pass through the pin mount 135 quick release pin 136 will usually for convenience purposes be left within hub 134 when rear wheel 82 is removed by the seat occupant or an assisting party referring additionally to fig1 a through 13 the folding wheelchair 7 of the present invention has a transversely or inwardly pivoting upper side rail assembly 160 the upper side rail 160 has two members 162 and 164 members 162 and 164 are both pivotally connected with the posts 20 via pivot collars 166 and 168 respectively pivot collars 166 and 168 pivot along the axis generally perpendicular to the.