bverdon said:Thanks Dave. I guess what I don't understand is, how can you determine FTP from a ride file? Per the link you provided...that was the best way to determine FTP.
Actually, you're reading that backwards, the list is given in order of increasing accuracy. The gold standard is to actually ride a time trial that takes approximately an hour on a well rested, highly motivated day. Inspection of a single ride file ranks number 7 in terms of estimation accuracy.
Quoted post said:... I mean...wouldn't it have to be a specific ride file? So...I went for an easy spin...looked at a ride file...now what? See what I mean? I think it has to have more structure...something you can reproduce.
Yep, you can't derive much info from a ride that was never intended to take you to or beyond your FTP. That's part of the reason inspection of multiple ride files is a better estimate, better chance of pushing yourself up to and beyond FTP during a lot of rides, at least for a competitive cyclist. But the unstated assumption in ride files is that you push yourself pretty hard. It's in the book, but basically competitive cyclists tend to push themselves pretty hard in a lot of situations, taking a look at the power distribution histogram and noticing any sharp steps down on the high side of the curve can give you clues to your current FTP. But you're right, you can't just noodle around the neighborhood and expect your FTP to jump out of your power data.
Quoted post said:I would have to imagine that I would have to actually plan an all out 20 minute interval to determine this...as the previous post...and go with an avarage wattage reading...and multiply by 95%...that one makes the most sense to me.
Cool, whatever works for you. As Alex points out it's plenty accurate especially as you first get started. But don't dismiss tracking your regular long intervals, it's easier as you're presumably going to do those intervals anyway and it helps maximize training by minimizing dedicated FTP testing days. And again, it's offered as the second best way to estimate your FTP right behind a dedicated hour long time trial. And that's coming from the coauthor of the book who is well aware of the other author's 20 minute *0.95 method and chose not to include it in his top 7 list.
-Dave