I recently purchased a 2014 El Mariachi frameset and have started to compile components for the build. I noticed on the Salsa site that most of their builds have setback seatposts. Any reason for this? The Effective TT length measures about the same as my typical bike. I'd like to purchase a straight syntace P6 hiflex seatpost since I've had good success with these in the past and wanted to make sure there's not something I'm missing regarding Salsa sizing.