Power Distribution Chart and FTP



specialized31

New Member
Aug 3, 2006
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I've been relegated to the trainer for the past 8 weeks focusing mainly on L4 efforts via 3x20's and 4x15's. Looking at my power distribution chart for those 8 weeks I see a definite even plateau in 3 bins (10 watt bins) and then a significant drop in the fourth bin. Could this be a close approx (within 10 watts or so) of my FTP even though I've done no efforts longer than 20 minutes in that time frame? I plan on testing outdoors in the next week or two but wanted to use my chart numbers to give me something to shoot for.
 
If I understand you correctly, yes. If you lump all of your level 4 work together and the power distribution for strictly those efforts has a large drop off after a rapid rise, or as is your case, a plateau, then the bin before the drop-off approximates FTP.

Consider the indoor trainer you are using. Perhaps others can chime in, but indoor numbers typically understate what you will find in your outdoor testing. I use a fluid 2 and read somewhere that it is harder to produce FTP on that unit. YMMV.
 
woodgab said:
If I understand you correctly, yes. If you lump all of your level 4 work together and the power distribution for strictly those efforts has a large drop off after a rapid rise, or as is your case, a plateau, then the bin before the drop-off approximates FTP.

Consider the indoor trainer you are using. Perhaps others can chime in, but indoor numbers typically understate what you will find in your outdoor testing. I use a fluid 2 and read somewhere that it is harder to produce FTP on that unit. YMMV.
That's what I thought. My three 10 watt bins that are pretty much indentical reflect the window that I've been working in the last 8 weeks. The fourth bin I can reach during my intervals but not as consistently as the other three. Although the fourth bin is significantly higher than it was just a few weeks which is a good sign.
 
If you've been riding isopower intervals for the last 8 weeks, then your bins will reflect what you *have done* and not what you *can do*. IOW, if I ride at 200w all day every day, then there's going to be a big drop off at 205w, even though that's nowhere close to my FTP.

To use the bin drop-off method, your power distribution needs to be composed of rides of various types and intensities (esp. spirited group rides). From http://www.cyclingpeakssoftware.com/power411/threshold.asp :

Of course, this method works best if the time period being examined includes some high intensity training and/or racing, which serves to make the distinction between sub-threshold and supra-threshold efforts more distinct.