175mm long spindle off sons old bmx bike. screw nuts on both sides then place inside dropouts.
unscrew entire length of the spindle. when the spindle is removed, 135mm spacing is left. the frame remained nice and straight. i also had to tap spindle back in place every few rotations of the nuts.
I did this to utilize a current wheelset i had ( spinergy m1 spox) . dropped about 2 lbs off the stock
wheelset. A Gusset spacer kit is used and I have a perfect chainline.