My brother and I are doing a 12 hour TT relay at 24hrworlds.com in a few weeks. We think each loop will be ~45 minutes (hopefully faster!). My recent FTP is around 290. I'll be doing essentially 45 minutes on 45 minutes off for 12 hours but will be warming up before I start each loop. What do you think would be a reasonable effort level? 80% of FTP? With no swimming and running I thought 80% for the first 4-6 loops would be about right and then bump it up if I can.