frank.youngman
Retro Guru
As always it depends.Frames are designed for 130 or 135mm OLD (dimensions across outside spacers).If you use the smaller axle on a 135mm steel frame,odd are that it will bend in and you have the correct amount of axle within the dropouts for safety.Stiff ali frames maybe not.
If you just stick two spacers,one on each side, on the 130mm OLD axle two things will happen.Firstly you will have less axle protrusion into the dropouts,which might be a safety issue.Second you will alter the position of the cassette relative to the frame which will affect chainline and indexing.If you put both spacers on one side you alter wheel dish which will need fixing,plus one side of the axle will have minimal or no protrusion into the relevant dropout.
My motto: do it once and do it properly
If you just stick two spacers,one on each side, on the 130mm OLD axle two things will happen.Firstly you will have less axle protrusion into the dropouts,which might be a safety issue.Second you will alter the position of the cassette relative to the frame which will affect chainline and indexing.If you put both spacers on one side you alter wheel dish which will need fixing,plus one side of the axle will have minimal or no protrusion into the relevant dropout.
My motto: do it once and do it properly