Originally Posted by
rccardr
With 120, I generally cold set instead of spreading. And I generally advise against going up more than one 'size', so 120 to 126 or 126 to 130, but not 120 to 130. 10 mm of cold set or spread can cause problems with the brake bridge and/or chainstay bridge if there is one.
Good news is by going to 126 you can do a LOT, like a 7 speed freewheel on your existing wheelset (respaced to 126 and redished), or any mid-late 80's Japanese hubs laced to a modern set of rims on which you can use 7 speed or '8 of 9' or '9 of 10' (look up those terms for a full explanation) on the narrower freehub.
...this, pretty much ^^^. I just finished cold setting a 126 Pinarello to 130 so I could use some OK 8 speed wheels that I had. It came to me with a complete 8 speed Dura Ace setup, with a 7 speed 130 wheel stuck in there at 126.
I assume it worked for whoever put it together that way, but it bothered me.
There are a whole lot of Paramounts from the 126 era sporting Shimano indexing systems that work very well, if indexing is what you're after. They are, of course, different from the previous generation of Chicago cage built Paramounts, but are wonderful bicycles IME.
You can still get a pretty good top to bottom range of gearing with a 120, 5 speed rear cluster, if you just look for one of those swell Crane derailleurs that they used to put on the touring Paramounts at the time.
I would probably not cold set one of those to 126, but I've certainly done things that were more radical.