What about a red-band Nexus 8 instead (SG-8R36). They are 132mm wide. You could theoretically cut the nut (nut holds the dust cap on) on the non-drive side in half and get it down very close to 129mm. Cold setting 126 to 130 should be easily doable. The nut would have to be cut in half with some precision, to maintain the parallel sides (ideally cut in a lathe for example).
I'm planning on installing a Nexus 7 on a 126mm spaced bike. The Nexus 7 is 130mm wide, I'm going to cut the non-drive side nut to get it really close to 126mm
Of course, the Nexus 8 is only available in painted grey. So if aesthetics are concerned, you might have to stick with an Alfine. Supposedly the SG-8R36 has the same internals, but I don't know for sure.
I believe that supporting the brake bridge and the bridge between the chainstays might be in order for a cold setting of that magnitude (126 to 135).
Edit: Support as in some sort of external clamp to reduce any stresses on the brake bridge.
Last edited by krome; 12-04-11 at 06:34 PM.