Time trials are individual events that can range from something as short as a 1km prologue, all the way up to a steady-state 100-mile effort. More commonly, time trials tend to fall somewhere between 20 and 60 minutes, but shorter efforts are particularly common for hill climb time trials in the UK.
For all time trials, regardless of distance or topography, the goal is to complete the course in the fastest possible time. With no teammates to draft off of, aerodynamics play a huge role in your ability to successfully time trial. Much like watts per kilogram is a great indication of your ability to climb, your watts per CdA (drag) is a great indication of your ability to time trial.
Pre Race Fueling:
Flat courses don't nullify the benefits of a lightweight bike, but if your race is a climbing race where you plan to average less than 13mph, prioritize a lightweight bike. The higher the speed in relation to that 13mph threshold, an aerodynamic bike will be more effective at time savings.
A waxed chain is a proven place to save valuable watts. For more information on waxing your chain, check out this thread on the TrainerRoad Forum.
The same advice on weight/aerodynamics for bike selection applies to wheels, with one additional threshold to consider. Unless it is a hill climb time trial, you will likely want deep section wheels. Depending on the wheelset, the general consensus tends to be that if you plan on riding slower than 28mph then a solid disc rear wheel will not yield additional savings.
Tires are another spot to save precious watts, and this space is constantly evolving. For more information on tires, check out the TrainerRoad Forum.
Most time trials will have you performing at a pretty consistent speed. While drivetrains have improved over the years, cross chaining is still a way to add unwanted drag. When picking chainring sizes, pick the one that will allow you the straightest chain line on race day.
A skinsuit can be the most impactful equipment choice for a time trialist. This is another rapidly evolving space, so stay tuned to the TrainerRoad Forum for the latest discussion on this topic.
Gloves have proven to be minimally effective, and in some cases slower for specific athletes. In terms of equipment choices, gloves are an area of minimal concern.
Helmets are a very specific piece of equipment that vary from person to person. It depends on the position of your head in relation to the rest of your body and your direction of travel.