I am a mountain biker that has been clocking a lot of road miles lately. I know that back mounted hydration systems are not popular with the road crowd. I hardly ever see a serious roadie with one. I was curious as to why.

CamelBak makes a road model that has proven to actually help aerodynamics. Also, I can't imagine having to stop pedaling to get a bottle in and out of the cage.

Is it a fashion thing? Or, is there a practical reason? Just curious.