Originally Posted by CrossChain
A simple solution that MIGHT work. I have an old Spec. Allez (their crit-style main racing frame in the mid 80's) with stiff Specialized proprietary tubing and 126 spacing. Fretting about a wider cassette/axel, one day I simply applied a surprizingly little pressure with my thumbs, and a 9 spd rear wheel slipped on. There was nothing to it. About 4 seconds of extra effort and I've enjoyed perfect performance since. Wheel removal out on the road is easy....worth a little experiment if you haven't tried it yet.
Yep! I do this on my aluminum road bike, that is I use a 9-speed wheel (130 mm hub) in the 126 mm dropouts, simply by squeezing them open a bit when I need to change the wheel. It's not safe to cold set an aluminum frame, but it seems perfectly safe to do what I do.
I asked about it on rec.bicycles.tech, and it turns out dozens of people do it with no problems at all, some for 10,000 miles+.