Can you make sense of this? Wack FTP numbers

afrost

 This question is for my husband.  Tony has had a power meter (SRM) for a couple of years now but really, it is just a fancy read out to him.  He doesn't actually "use" power (like we do here).  Rather, he will just randomly report out to me (or others) what he averaged on a given ride.  So here's the puzzle.  In November at the LV LC World Championships he averaged 246 watts for 120 K (about 3.5 hours of biking).  Let's assume he could hold 80% of FTP for this distance - which is pretty hard - this gives him a FTP number somewhere around 300 watts (which I think is reasonable - he's a strong cyclist - a 5:00 - 5:10 IM guy).  This weekend (after I said he should get his bike with power on the trainer and start actually USING his powermeter for something useful!) he put his bike on the trainer and did an FTP test.  He did 20 minutes as hard as he could (and I told him to take 90% of that to get some kind of FTP estimate).  The result was 224 watts.  That gets him a FTP number of around 200 watts!?

The question:  could he really have lost all this power in the last 2 and a half months (he has not been just sitting on the couch since early November)?  Or are some people just really bad at generating power on a trainer? (and therefore if he could get outside his power will be more like what it was).

Any insights would be appreciated.

---Ann.

 

 

 

Steven Ford

I know I have a harder time on the trainer putting our power than on the road, I believe most people will tell you there is a difference between indoor and outdoor power.

 

That being said was the PM zeroed and calibrated before he started?

Scott Alexander

If I recall, for a 20min all out test (after WU), you can take 95% of that, not 90%. So...224 * .95 = 213w.

Usually, also, it's about a 7-10% dip between inside and outside. So, for outside I'd say: 213 * 1.07 =227w (low end) to 213 * 1.10 = 234w (high end).

Coach Rich

Was the 246w average or normalized watts? If normalized, then a high VI would make that 246w sorta inflated.

Shaughn Simmons

Scott A. nailed it below......

afrost

Thanks, all! Good stuff. I appreciate your insight into this. Bottom line still though - he's got work to do! ha!

---Ann.

Coach Rich

Posted By Ann Frost on 30 Jan 2012 12:54 PM

Thanks, all! Good stuff. I appreciate your insight into this. Bottom line still though - he's got work to do! ha!



---Ann.

Yep...but more importantly he's got LEARNING to do! Your DH has been riding around with a very, very, very expensive Cateye vs an SRM...

Kevin Walter

Almost certainly Steve F has it. Have to zero and calibrate before every single ride. It only takes 2 seconds, but data can vary widely if you don't do it.