I have and old custom 531 frame with 120mm spacing and a freewheel type rear hub (campy NR). I am considering opening it up to 126mm to allow the use of a 7 speed freewheel. I have read Sheldon Brown's instructions on cold bending the stays but I am still a little confused. It stated that the added space was required on the right side but further down it indicates that both stays need be be moved equally. Do I move the right stay 6mm or move each 3mm?
I would even consider opening to 130mm but I not currently prepared to buy a new rear wheel to go to a cassete type hub. I am also concerned about damaging the frame by the extra movement. Any comments on this would also be appreciated.