As this is a supported ride, you should have a backpack-style bag with water bladder, rear mounted rack with bag, or top-tube mounted bag. There are many companies on the market now so shop around and see what size, color, and options are right for you. Most folks use a backpack-style bag. If using a rear mounted rack and bag, make sure it's secured and understand it will impact bike handling over rough or muddy terrain. If you want to be a minimalist, put a small top tube pack and/or saddle bag on your bike.
Bike Computer. Some are wireless. Some measure cadence (pedal strokes per minute). But all measure speed and average speed. This is critical for getting in shape. And helpful in maintaining an appropriate pace during the ride.
Lights. Front facing light and rear-facing “blinkie.” If you don’t have them, make sure someone is in front of you and someone is behind you. It is highly recommended you have a front light as we travel through multiple tunnels on the ride.
Pump. Can be mounted on bike, carried in jersey pocket, or in pack/rack of choice. The Morph from Topeak is a recommended pump but there are many varieties on the market. Another choice is to carry CO2 pump which requires you to have CO2 cartridges.
Hydration. As mentioned above in the Pack/Rack section, most folks use a backpack-style pack on this ride. This type of pack will also hold a hydration bladder. Make sure you choose a bladder larger than 70 ounces or 1.5L. Your bike has two water bottle mounts. It is recommended to have water bottles as backup to your hydration bladder, especially on Day 3. How much you need to drink depends on your fitness and personal choice. Do not wait to drink until you are thirsty. Hydrate often on the ride. Consider bringing an electrolyte powder with you on the ride. Another option for hydration is to drink coconut water.
Sustained Energy. While this ride is supported and we begin every day with breakfast and stop for lunch, you will need to digest food while riding. If you're not used to eating while riding, practice. If you're not comfortable doing so, make sure you dismount and move off the trail to eat. There are many options to provide energy throughout the ride. Energy bars, gels, goo, bananas, apples, trail mix, etc are all excellent sources of fuel your body will need to complete the ride. Make sure you know what your stomach can tolerate while riding before this ride.
Tools. In your pack, bag, or jersey you should have energy gel/food, 2 spare tubes, tire levers, chamois cream, band-aids, pump or CO2 device, and bike multi-tool. Optional items are tube patch kit, bike lock, sunscreen, moist toilettes.