Originally Posted by
T-Mar
The 600 Ultegra are 10mm diameter axles. Next step up is 12mm, then 15mm. Increasing the axle diameter increases its stiffness. Larger axle diameters, usually in conjunction with thru-axle technology, are common practice to stiffen the axle-fork interface on modern bicycles equipped with disc brakes, as it decreases disc rotor deflection and subsequent pad rub.
Well I guess that's that, will need to get new wheels after all. Shame I just got a campy driver for the spare set! I didn't try too hard but these definitely don't seem to want to fit into the rear dropouts.