While we can’t cover every detail here are some tips and ideas that might help you start to plan for WestX.
Whether your planning to ride through the night or bivy overnight, you should be able to ride 120 miles of gravel comfortably and recover enough to do it again the next day. While there are a few climbs, this route is generally pretty flat, but the road surfaces can be very rough. Work out the fit and comfort issues in advance and in your pre-rides throw in a dose of sustained rough riding to make sure you have your set-up dialed in. (Blisters on your hands or saddle sores that develop on day one are not going to get better as the race progresses).
Lots of personal preference here, but whatever you ride it needs to have the capacity to hold 6 hours of food, at least a gallons of water, as well as your cold weather, and emergency equipment. Tire slashes are always possible, multiple tubes and patches are cheap insurance. General spares (chain links, misc spare bolts, and cables) and the knowledge how to repair whatever breaks is important. Dust and or mud will creep into everything if you have equipment sensitive to fine particles have a backup plan. Dry lube is highly recommended.
Maps and GPS files of the route will be provided in advance. Study them, know the mileage between turns and carefully consider the distances between water sources. A word of caution, from satellite photos you’ll see lots of alternative roads or what look like roads especially in the Hamlin Valley. These are cattle and wild horse trails that frequently fade to nothing. Stick to the official route.