I had a road bike wheelset with aluminum axles. The front was problem free, but there were issues with the rear - the hub design did not have the freehub body fastened to the hub shell (like Shimano has) but instead the edge of the hub shell and the edge of the freehub body made up the freewheel mechanism, and the whole thing was held in alignment by an aluminum axle passing through four sealed cartridge bearings. It groaned and creaked and skipped when I put any power down. I never swapped it for the (available) steel axle, but I suspect that would have allowed the thing to function properly under my 270 lb weight and reckless riding habits. If the hub had been a SHimano-style freehub like gorshkov's XT then I am positive it wouldn't have been a problem, just as it wasn't a problem on the front wheel.