I did my first FTP test tonight since November and was pleasantly surprised with the results but curious about how to interpret some of the variables. I did a lot of interval work this off season following the Endurance Nation plan. This was really the first time that I have followed any plan and definitely the first time I did any real structured interval work. I borrowed something from the TBB folks and did quite a bit of these intervals pushing a harder gear at a lower cadence. I’ve noticed the last few weeks that I’m getting up hills more easily than before so I had a feeling my FTP had improved but wasn’t sure how much. When I tested in November after my first tri season my FTP was 229 watts. This go around it was 247 watts. I know that is shit compared to some folks around here but nice to see the number trending in the right direction.
There are a few variables that leave me wondering exactly how to interpret this data. First, my last test was using my training wheel w/ Powertap indoors on the trainer. I’ve always noticed that my power is higher outdoors. I think it is just mentally difficult to hold my power indoors. I can push myself harder outdoors but not sure why. This time I tested outdoors and also with my race wheel (disc with Powertap). I’m sure that there is some wattage difference between the two power meters but I would guess it is small. Any way to determine this easily?
Secondly, my protocol was slightly different out of necessity. I typically do a 15 min warmup followed by a several really hard efforts to open up the legs and then 2 x 20’ (2’ easy between the two sets). Then I take the entire 42 minutes and create one interval and use the normalized power for that as my FTP. I’m sure there are other protocols but that is what I use. On this ride I had to ride for over an hour to get to a place with more open road so I wouldn’t constantly have to stop. I did several really hard efforts in this hour. Then I did a 21 minute interval where I had to stop a few times to cross a street (which is why I added the extra minute) then I did a 4 min easy effort (totally forgot that I usually do 2 min) followed by another 21 minute effort that only had one very short stop. Then I took the entire 46 min effort and took the normalized power as my FTP. My guess is the actual FTP is a bit higher given the much longer warm up and slightly longer intervals. Is my thinking right here? Either way I definitely felt stronger out there than I was expecting to especially since I just started hitting the weights hard again at the gym and did a big leg intense workout last night. I was expecting dead legs because of that but I felt stronger than ever.
Is there are question actually buried in there somewhere?? 
Oh, yeah , I see it now!
Yes, your FTP is probably higher than you recorded.
Sounds you are doing fine either way…
I’d take the avg of 2*20 intervals NP * .95 = FTP.
You cannot compare outdoor test with indoor. Indoor always much lower. Stops in a test is a no-go.
Why are you only testing every four months???
It just ended up working out that way. My plan had tests every 4 weeks but that always seemed to be a day that I had to change my workout.
First, my last test was using my training wheel w/ Powertap indoors on the trainer. I’ve always noticed that my power is higher outdoors. I think it is just mentally difficult to hold my power indoors. I can push myself harder outdoors but not sure why. This time I tested outdoors and also with my race wheel (disc with Powertap).
It might be more than mental:
http://alex-cycle.blogspot.com/2009/01/turbocharged-training.html
In Reply ToI’m sure that there is some wattage difference between the two power meters but I would guess it is small. Any way to determine this easily?
There is. See here about checking the calibration of your meter:
http://www.midweekclub.ca/powerFAQ.htm#Q23
Great info. I knew I wasn’t imagining the differences. I guess I need a bigger fan.
I’ll definitely have to check on the calibration. After my post last night I noticed in the Performance Manager that this test produced my highest ever 20 min and 60 min power readings by quite a lot. Part of that is improved fitness but I think it will be valuable to know how different the readings are between the two wheels. The interesting thing is that I have used this wheel for several training rides outdoors though not for any interval work. I’m thinking that I might just do another FTP test this Saturday on the same course using my training wheel and see how the results compare.
As a point of reference, I found that indoors with my piddly little fan I can’t ride above 140bpm and pathetically low watts (less than 200). And I’m dripping with sweat and seriously overheating. Outdoors I can ride for 1hr at 175bpm plus at over 300W…
Regarding the test protocol, my best suggestion would be to do the test regularly at least once a month using the exact same course. If you are going to do it outdoors then pick a course you know you can reliably ride the same and do the test that way. As others mentioned, stoplights and stopsigns can really screw things up if you are trying to get a truly objective number. They can also add some significant variability to your numbers, even turning what you thought was a 2x20min interval into effectively 4x10min or similar. I found that the data was still useful as long as I rode exactly the same course in the exact same way. It’s not ideal but it works reasonably well.