When going fast and getting aero is your top priority, the serious options are limited, but Enve's SES 7.8 Disc is definitely among a very select group of aero rims sets that is designed and–importantly–tested to perform better than anything else. One of the many aspects that sets this rim set apart is just that: it's a set of front and rear specific rims, each of which is optimized for the position it occupies on the bike. The front rim has a 71mm depth and 29mm external width at its widest point (which is around the midpoint from the bead to the spoke nipple bed. The rear, on the other hand, has a 78mm depth with a 27.5mm external width. Both have an internal width of 19mm and are optimized for 25mm tires.
Of course, a wheelset isn't just about the rims, but when it's rolling on Chris King's R45D Centerlock hubs, you know it's going to be awesome, and just keep getting better with age. Finished out with Sapim's stellar CX-Ray bladed spokes, this wheelset is light, crazy fast, and in case you didn't notice, it looks incredible.