25% FTP Loss in 6 weeks?

[Wtullock]

Hey all, new to the forum. I’ve been riding for exercise on Zwift and outside for the past two years. I was completely new to cycling before that. In that time I’ve raised my FTP from 207 to 316 fairly steadily. However in the past 6 weeks I’ve had a significant loss in top end power and endurance. An example would be that on March 6th I was able to hold 344 watts for 10 minutes and 329w for 20. As of today I could barely get 279w for 10 and 260w for 20 mins. My training volume is down about about 15% in that time frame and I haven’t been doing many races or top end workouts, but everything I’ve read has said that the drop I’m experiencing is much higher than average. Has anybody else ever experienced this? If so, any tips to get back?

 

[Cookster15]

Assuming your trainer doesn't have an accuracy issue pretty sure this must be because you are tired for some reason. Have a good sleep and try again will be very surprised if your FTP doesn't get back to close what you recorded.

BTW, an FTP is 316 is huge for someone 'new to cycling', can you test yourself on a different trainer and see if you get different results?

 

[Wtullock]

Thanks for the reply! I have a Kickr Snap that’s about 18 months old at this point so I’m wondering if something is wrong there, but whenever I do a spin down it is normal.

As far as testing I have used multiple different peloton bikes to cross test my FTP and they’ve all been close to what I got on my Kickr. It’s certainly possible it’s not accurate though. Also I guess new cyclist isn’t fully accurate, I started training for a triathlon in early 2023 on a peloton and got my FTP to 240 on that and then switched to structured training on Zwift in late 2024. I had just hit 316 in March after steady training and improvement. I’m also 191cm and 90-93kg so larger than most cyclists, and before switching to cycling I was doing a lot of lower body lifting.

 

[JayKosta]

Things such as sleep, diet, 'other physical work', seasonal allergies, etc. can all affect your day-to-day performance. Even simple things such as early morning sunlight disturbing your sleep pattern.

 

[Wtullock]

Well…this is embarrassing, but I’ve found the culprit. The yoga mat under my kickr snap setup was rubbing on the back wheel. Somehow I didn’t notice it for 6 weeks. I looked down today and noticed that the tire had burned a hole in the mat from all the friction. Fixed it and everything was back in more normal ranges today.