@Fixedwheelnut did ~344 miles at the Mersey Road 24hr so 250miles (with a less favourable course and less organised supply stops) is definitely possible.
I did 334 on 72" fixed unassisted, my club mate Rob Bullyment narrowly missed out on our club record last year at the Mersey Roads by 2 miles :)
He did 461.3 miles on 86" fixed achieving 9th overall he only spent 20 minutes off the bike, phenomenal ride and one of the furthest known on fixed. :)
@Fixedwheelnut did ~344 miles at the Mersey Road 24hr so 250miles (with a less favourable course and less organised supply stops) is definitely possible.