The High Cost of an Inflated FTP
If you overestimate your FTP, you’re essentially turning every workout into a "fail" before you even clip in. Instead of training the specific energy systems you need to get faster, you end up doing too much high-intensity work, which leads to massive fatigue, missed intervals, and eventually, total burnout.
Think of your FTP as the foundation of your entire training house. If that number is wrong, every room—your Sweet Spot, Threshold, and VO2 Max zones—is built in the wrong place.
Why this matters for YOUR training
When your FTP is set too high, your "easy" days aren't easy enough, and your "hard" days become impossible. Here is what happens to your body:
Zone Creep: If your real FTP is 250W but you have it set at 275W, a "Sweet Spot" workout at 90% (247W) is actually your true Threshold. You’ll be gasping for air instead of building aerobic endurance.
The Fatigue Spiral: You’ll rack up way more TSS (Training Stress Score) than your body can actually handle. Your TSB (Form) will plummet into the "Red" zone (below -40) much faster than it should.
Mental Burnout: Failing workouts is demoralizing. If you find yourself constantly cutting intervals short or quitting halfway through a session, your FTP is likely the culprit.
Real-world example
Let’s say you’re doing 4x10-minute Threshold intervals. At a correct FTP of 250W, these should feel "comfortably hard"—you’re working, but you can finish.
If you’ve overestimated and set your FTP to 275W, those same intervals ask you to hold 275W. That’s not Threshold anymore; that’s a 10-minute maximal effort. You might finish the first one, but by the third, your legs will be screaming and you'll likely stop. You’ve missed the "Threshold" training effect entirely and just dug a massive hole of fatigue.
How to spot the "Ego FTP"
You might be overestimating your numbers if:
You dread every single workout on your calendar.
You have to "backpedal" or take extra breaks during standard Sweet Spot intervals.
Your heart rate is hitting its maximum during what should be a steady Threshold ride. Check this post on decoupling
You can only hit your numbers if you are 100% fresh, caffeinated, and have the perfect fan blowing on you.
Try this: The "Reality Check"
If you suspect your FTP is too high, don't be afraid to lower it by 3-5% immediately. Try a standard workout like 2x15 minutes at 90% of your new, lower number.
If you can complete it while maintaining a conversation (briefly), you’re in the right ballpark. It’s much better to have a slightly lower FTP and complete 100% of your workouts than to have a "pro" number and fail half of them.
Summary
The Effect: Overestimating causes you to train in the wrong zones, leading to overtraining and plateaus.
The Fix: Be honest with your testing. If you can't finish your workouts, drop the number.
The Goal: Consistency beats a high number on a screen every single time.