I have a Trek 620 (Reynolds 531 lugged steel frame) from the mid-80s the rear dropouts are spaced at 126 mm. I'd like to be able to run an 8- or 9-speed cassette and I was wondering about the issues involved with running a modern road hub with 130 mm spacing without adjusting the frame spacing.
It seems to me that the rear triangle would have the ability to flex 4 mm without needing to be cold set – at the expense of a small misalignment of the dropouts.
Are there problems with doing this? Other than the slight hassle when installing the rear wheel?
Would it impact the value of the frame – the bike is a rider, probably not a candidate for a restoration (frame could use repainting and I'm not sure the components are original, the wheels definitely are not)?