fascinating... i've always extended a post mount by using both halves of a threaded brake pad Pivot Mount from a v-brake, and juggling washers/cups as needed.. Why would there only be one half of that pivot system shown on that drawing? and i've also never seen that spacer on a bike... ever. Will wonders never cease... Still baffled by the use of 1/2 of a pivot mount... weird and useless. Some engineer is probably very proud of that drawing... half a pivot mount... hmmmm....... liking the spacer.... and the half pivot could be to allow for the bias on the spacer... i'll stick to the tried and true BOTH HALVES and No spacer method.... now, if i was going from 160 to 203... add the correct spacer andpivot as needed.... I've never bothered going from 160 to 180mm... and the two bikes i upped to 203 were side mount forks....