Racing the mind, an ultra endurance event be it supported, semi-supported or un-supported is as much a mental battle as it is a physical one.
What i do......
#1 Break it down
Before I do an endurance race I like to "dechunk" the distance in my head or even better put it on paper. For example when doing a 24 hour mountain bike race I would break it down into 2 parts of manageable time segments. First would be every hour within an hour I would need to consume 500ml to 750ml of fluid and eat something small, sweet or savoury every 20 minutes. Second would be to assess effort/pace every 2 to 3 hours allowing for better control, I would use the same approach for longer events. Most cycling training GPS devices allows you to set alarms, I set certain duration and distance alerts to ensure that there is constant refueling.
#2. Training specificity
Practice makes perfect - it is a simple formation of habit, train your body and mind. Improve and or build abilities that will match physical and mental demands of the event. If you are not able to do it on your own then find someone that can guide your training towards your goal.
#3. Learn how to gauge your effort
Ultra endurance cycling is about pacing and spending just the right amount of energy.
#4. Check equipment
Clean, check and maintain your bike, it is much easier to prevent mechanical mishaps than trying to fix them in the dark in the middle of nowhere.
#5. Know the limitations of your equipment
The simple detail such as knowing how long it take to run your light on different modes or how long it takes to fully recharge the battery will make a huge difference.
Technology is great but will and can fail when needing it most, when using a navigation device for the longer 1000km I always have route directions on paper as a back up.
#7. Sleep monster
Bulk up on sleep, I have found that the best way to try and remain sharp is to arrive at the start line well rested. Save the caffeine pills, drinks and gels for when you really need it. Sleep in a 90 minute duration, or uninterrupted for 180, 270 or 360 minutes when needed, it is a bit of gamble because you can lose time and distance or you gain time and distance, all depends when you choose to and how long you sleep.
#8. Keep in mind
Focus on what you can control - your pace, nutrition and sleep. What everyone else is doing is none of your business.