Heyo. I wanted to put together how I built a very fast TT bike over time with a relatively low budget. I started racing time trials around 2014, and liked it so much I decided to put together a dedicated bike instead of using clip ons with my road bike.
I think in general there are two big advantages:
1. The most important aspect is is positioning, you can get a position that is both really aero and powerful with a dedicated setup.
2. Weight is a nonfactor so you can organize the bike to be purely Aero.
The bike we will be talking about is this Cervelo P2. Feel free to ask questions as we go along, everything here has a story and a purpose :)