I have a classic vitus 979 aluminium road frame where the rear dropout width is 126 mm. Most of the things I hear is that you should not use force on an alu frame and try to fit in an 130 mm hub in there, like you could on a vintage steel frame, but some say that the vitus 979 frame has so much spring in it.
I'm not sure what to do, I want to have modern wheels on it, should I try to force it?
First, try to find a modern wheel that's the right size. They are still made and you can get very shiny ones that will match the bike very nicely. Or get a 120mm fixie hub and add 3mm of spacers each side.
If you must use a modern wheel, try to shrink your hub. Many hubs have washers between the locknuts and cones, or other spacers. If you can remove even a couple of washers to bring the hub width down you're better off. Ideally keep the hub symmetric, but a millimetre out is not the end of the world. Note that you'll need cone spanners and a little skill to adjust things after you do this. With a modern sealed bearing hub it's easier, but with a classic bike like that I suspect you're not putting new wheels in it.
Finally, spreading the frame 4mm should be fine. It'll make getting the rear wheel in harder. With aluminium, do not try to cold set the frame. Once the aluminium yields a lot of the strength is gone and you've basically destroyed the frame.
I don't necessarily recommend it, but I own a Vitus 979 and did this about 10 years ago so I could upgrade to a 9 speed cassette and STI shifters. I haven't had any problems with it. But I haven't put a lot of miles on it since the change and I'm under 150 lbs. Some of those miles have been on dirt roads.
I stripped the frame about a year ago and the dropouts measure about 128.5 empty.
The idea about trying to narrow the hub won't work because 1) you need the space to fit all the sprockets in the cassette 2) if you try to make space only on the left side your wheel alignment will be whacky 3) most modern hubs don't have spacers or cone washers that can be deleted from the assembly.
One reason I haven't ridden it much since is because I never felt totally confident about the integrity of the frame after I forced the wheel to fit. Also, once I was able to afford a new bike I enjoyed riding the new bike more. I think you are better off keeping your Vitus as a classic and saving a up to buy a new bike with modern components.
If you're still considering it, remember that my experiment of one doesn't mean you'll have the same success.
