Your body position and the bike’s aerodynamics play a significant role in time trials. A couple of years ago, I read a comparison of different body positions and their influence on the finishing time in a 40k time trial.
I am not sure, but I think I saw these results back in 1997, so this is not breaking news, somewhat nostalgic news.
Aerodynamics is important in time trials
The interesting question is, how much time can you save by using expensive aero wheels, an aero frame, or saving some pounds? There are probably more precise answers to these questions than this report calculates for you, but it gives you an idea of what difference these changes can make.
One of the interesting findings is that slower riders will benefit more from a lighter bike than top riders, while aero wheels and frames will give the most significant advantage to faster riders. This is probably because the aerodynamic drag requires a relatively larger workload at high speeds.
Optimized aerodynamics is better than weight savings
This report concludes that the most significant changes in aerodynamic drag and cycling performance come from changes in body position. A more aerodynamic body position can improve your 40k time trial by over 6 minutes (that is something!)
The report also concludes that improving the bike’s aerodynamics is more important than weight savings. A pair of aero wheels can reduce your 40k time trial time by 1 or 2 minutes.
Find more inspiration for your time trial aerodynamics here.