I’ve done he Fred 5 times and i find it massively weather dependent.
last year was pretty good apart from the headwind on cold fell, the year before was pretty hairy, rain, sleet then snow on newlands was not cool and I know a couple of very fast (skinny and v. experienced) guys who where hypothermic after the descent and had to retire.
a couple of years before it was really warm and getting enough fluids in was an issue… you just never know!
if you’ve ridden the kielder and don’t want to do a crazy time then you’ll be fine- most time is lost on the flatter sections anyway…