drop out width - 130 v 135 mm
 

What are most CX bikes? Anybody know what the Bianchi Axis is?

I'd like to be able to swap my road tires onto a cx bike when I travel, but that won't work if the dropout widths are different. Beyond fit, I'd have to mess with the derailleurs.

the Axis is 130 mm. i believe most 'cross bikes are.

Bianchi's are 130 as are most cross bikes. I had been looking at a Planet-X frame on ebay......but the spacing was 135.

Like a lot of folks who started on road bikes rather than mtbs I have some perverse preference for 130mm, but there a quite a few Cross bikes with 135mm rear spacing. Salsa Las Cruces is one of the better ones. Ibex X-Ray, Nashbar's. There are plenty; and I think that as disc brakes are accepted we'll see more. I can't really see the justification for them other than compatibility with disc brake hubs but if others can explain, it would be edifying.

i'm not a wheelbuilder, but as i understand it, one benefit to a wider rear hub (presumably with a wider distance between the flanges) would be a theoretical reduction in dish.

this, of course, would result in a stronger rear wheel.

surly crosschecks are spaced at 132.5, that way you can use a road or mountain hub.

If your bikes a steelie and is 130mm, you can run 126mm and 135mm no problems with a little extra persuasion.

135mm spacing yeilds less wheel dish for a given cassette and hub. Less dish=stronger wheel. Good idea for a cross bike, IMO.