Originally Posted by
HillRider
As noted, new bikes and wheels bought in pairs use the same hubs and rims but may have different spoke counts with the rear wheel being the higher since it carries much more of the total weight. My Shimano R560 wheel have 16 front spokes and 20 rear spokes but otherwise both look nearly the same.
Now, since a rear wheel does carry more weight and the drive forces and gets sprayed with crud from the front wheel, it usually fails first from a cracked rim, broken spokes, impact damage, etc. So, the owner now needs to replace the rear wheel and is confronted with the cost so s/he looks for a bargain. The front wheel is still fine so the bike now has a mis-match.
This agrees with my thinking. It happened to me, the rear aero wheel failed first, I did replace it but at more cost than it was worth. I know of other cases where the rear wheel failed first and either the rider continued using the front or sold the front at a bargain price.
I think expensive aerodynamic wheels are best saved for special events, like time trials.
I don't believe an aerodynamic wheel is any better in the front as in the back.