I like to do a Oly about 4 weeks out to set my training and racing zones for Biking and Running. That will be my last race before a HIM.
My average power on the bike I will use as FTP. Before I had a powermeter I would use the speed and HR.
My average speed on the run I will use as my threshold pace.
I base my HIM zones as 80 to 85% of my FTP power for the bike and start my run at 90% of the speed I did the OLY at. At half way on the run I decide what to do with the pace.
I had success at 2 HIM’s last year doing that.
I’m not a great runner.