Seeing as FTHR is only 173, I won’t be averaging 184 for four hours thats for sure 😀
Looking at SPAM which I tried quite hard at, I averaged 167 for 2h50, Brecon Beast was 155 for 4h50 but that included 3 puncture stops so is a little low. 2013 Beast was 160 for 3h32.
So I reckon around 160ish which is about 83% MHR should be ok?
Everything I do lately, I lose a place on the last lap to a guy who is doing a massive negative split on his last lap (not the same guy but you see what I mean 😉 ) I just gasp away with nothing in the tank as they pace their way to moral victory.
This is just training for me rather than something I’m targetting so it will be a good scenario to try some disciplined pacing.