TTE @FTP determined mostly by fat oxidation. If op wants to better utilize get then they will need to to a threshold block…fueling with carbs…there I said it
Your body uses the fuel it has available but training at ftp for longer durations improved fat oxidation regardless of what you are consuming
Yes you can and it’s being done all of the time.
IMO, I think you’re over thinking the nutrition aspect. I try to follow principles and not over worry about what zone I’m working out in and how many carbs/ fat I need per zone. I personally follow principles and worry about more important things in life
This seems…a bit off. You might want to tweak your really hard work if it’s only getting you to 90min @ 88%.
You don’t think that eating enough carbs (“cake”) will help you maintain 90% of FTP for 90 minutes?
You don’t believe that your 5 hour power is highly correlated with your FTP?
What do you believe?
I’m not sure anybody really knows what limits TTE @ FTP, but I don’t think it is the rate of fat oxidation.
you couldn’t be more wrong.
I did that ride on nothing but GU Roctane and Gel
I took his comment to mean that you had to oxidize at least some fat to make it to 5 hours.
I don’t think that is right, but I do think you almost certainly would.
Well considering any effort uses both fat and carbs, of coarse you won’t do it on all carbs. I took it as you can’t ride 5+ hours putting just carbs in the tank
If FTP were correlated to 5 hour power Phil Gaimon would still be on the tour. His 20 minute power is world class. I know plenty of people that can put out a heck of a lot of power for a 20 minute test but can hold a meaningful percentage of it for 90, 120, 240 minutes. Everyone’s power curve is very different, and not simply by a multiple.
Are you sure you didn’t burn any fat?
I think there may be a slight confusion over terminology as I take fuelling to mean what I eat or drink, which is different to what the body actually utilises.
I’m 100% sure I burned stored fat. I didn’t fuel myself with any fat though.
I found this in a book I have, It has a estimation percent of carbs versus fat and percentage of your respiratory equivalent ratio. maybe it’ll help 
Lines up pretty well with a study I read on threshold training
RER and VO2max are two different things.
You’re right I’m sorry… I misunderstood the differences
So once, you go past a minute or two, everyone’s power curve in relation to FTP shows very small variation. Pretty cool. Where is that data from, do you have a link?
Here you go:
