One thing I wished I’d known before my first was that the really fit guys who win these things feel just as bad as normal people. they don’t breeze through it like one might a 2 hour race.
Chris Eatough, 24 solo world champ, once said that after 6 hours he feels knackered, as bad as after a massive day ride with his mates, wonders how on earth he can ride that another three times. He also described a feeling of absolute dread and doom as it goes dark, being quite scared in the early hours.
If you’re planning to complete it, rather than try to win it, then these events are mostly about what’s in your head, not your legs.