The biggest gain of TT/Triathlon bikes is moving your position from an upright seated position to a lower and narrower position, so "modding" the rider ;-) Aft

The biggest gain of TT/Triathlon bikes is moving your position from an upright seated position to a lower and narrower position, so "modding" the rider ;-) After that, skinsuits, helmets and overshoes are usually the best bang-for-your-buck (in no particular order) in terms of aero gains.