Originally Posted by
relyt
I didn't want to respace the axle since I have another bike with 135mm spacing and it is nice to be able to put that wheel on it if anything breaks.
IMO, 126mm to 135mm is too much. In addition to respacing, you need to think about the dropouts. They will have to be bent back inwards. In a stock frame the rear dropouts are parallel to eachother. When you respace the stays, they are no longer parallal. A 4mm respace really doesn't do too much. A 9mm could give you some problems. Sheldon Brown explains it somewhere on the site.
Tim