Joined: Aug 2010
Posts: 12,727
Likes: 2,105
From: Madison, WI
Bikes: 1961 Ideor, 1966 Perfekt 3 Speed AB Hub, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, 1980s Bianchi Mixte on a trainer. Others are now gone.
I am running 135mm rear hub in my 130mm spaced steel rando frame.
You really want to use the correct size hub spacing if you have an Aluminum for Carbon frame. But, steel has some give to it, so should not be a problem.
Different steels seem to be more flexible than others, my rando bike is very easy to squeeze a 5mm oversize hub into. But I have a 1961 vintage 120mm spaced Columbus tubing steel frame that takes serious muscle to get a 126 mm hub into.