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Power - Trainer vs road

I got a power meter a couple weeks ago and the readings I was getting while on my trainer were very consistent. However, last weekend when I was able to finally ride outside the readings did not make sense to what I was seeing on the trainer.

I am hitting my FTP on the trainer way faster than on the road. For example if on the trainer I get a power measure of ~230W I would hit the same on the road and perceive no effort on my part.

I am trying to learn to ride with power so not sure what am I missing.

Any recommendations or thoughts?

Comments

  • There is almost always a disconnect between the power #s on a trainer and the #s on the road. Some folks report the road power being lower; and some, like myself, have higher #'s for the same perceived effort on the trainer. Lots of speculation as to why that might be, but suffice it to say, you'll have two sets. Going forward you'll get a sense of what the difference is and it should be fairly consistent. 

    After multiple seasons, I know if I test indoors on the trainer, my outdoor test will be about 10w higher. So when I move to training outside I usually ride with an FTP ~10w more than I do inside. Short of doing tests in and out in the same week, you'll have to guesstimate a bit, but you will over time get a good feel for it and learn to adjust as you move from one to the other. 

    In fact most of the time I do my tests inside no matter what the weather, as it provides a consistent repeatable course to ride on. This way I have a good data set from year to year to compare FTP progress. Outside on the road I adjust my targets up to match the disconnect, and I might throw in an outdoor test before a race to lock in my numbers and make sure I'm doing the right thing on the road.

  • I see similar effects. Also you will have much more variability on road (second to second) -even on flats. One of the reasons I have my PM now show power display every 2 seconds and my Garmin for report Power every 3 or 5 seconds when on road. Also I will now do more HR vs power vs RPE comparisons I know what each Zone feels like on trainer but not on roads as most of my riding on trainer. It amazes me how Ill zip along at some "fun" high speed with a screaming high HR and not feel "bad" for a while and be thinking oh the PM isn’t working again" when it shows 300+ watts.....but later when looking at HR/power/speed it was "Real" ...but because of wind/scenery and such I didn't perceive the effort AT THAT MOMENT.....but.... then later would be shocked that it hurt to push 200w up a shallow climb (burnt some matches with the "EZ" PI's).....
    You’ll need to see what the power INside vs Outside offset is by doing some SS intervals at key power ranges and later at planned race pace/power outside then compare ....HR should be simular as well as RPE for each Zone. (ive typically raced at 20w higher than planned when going by RPE BUT that also had me at higher HR (by 10BPM) and I DID hurt more than I expected/planned on runs....probably should have trusted the numbers/training.)
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  • Rather than starting a very similar thread, I'm going to just build on this point, share my experience, and hope all others do the same.....





    I'm going thru these growing pains, too. Been cognizant of this 'problem' for about 2 years now and I still haven't quite figured out how to pinpoint an accurate FTP, whether it be for training zones or for race execution.



    At first, I was a 'tester'. Indoor test ended with humble numbers. Inside intervals seemed trustworthy. Then, would go outside for intervals or group rides and would crush that FTP for very long durations.



    Then, I moved to a 'swagger'. Took the interval work from outside and tried to come up with a swag FTP. This was difficult to trust because the rolling hills around here are tricky to do a 5' & 20' or a 20'(2')20'. The ups were ez to control. It was the downs that had me pulling my hair out. After I'd come up with the best swag that I could, I would chop off 10% for indoor intervals. But, that was still too hard. 20% difference seems to be in the ballpark.



    But, about this time, my power meter started screwing up...I think. Inside work stayed pretty consistent. I did start getting some respectable jumps in FTP but I was cheating the system. I was holding my old FTP for about 8' and would start to get tired. Then, I went into a VO2 mode of 1'on 15''off for the remainder of the indoor test. Hell, forget 120%, I'd hammer 150% for a minute then completely off for 15''. By doing this, I ended up with GREAT numbers, but I knew they weren't accurate because they weren't steady state riding. And, it was solidified as a muck up by the fact that I could rarely finish the entire intervals with this modified 'test'. At the same time, tho, I was going outside and just crushing my numbers. Not so high that it was an obvious equipment malfunction, but high enough to make me suspicious. Based on the fact that cutting the 20% for indoor work still wasn't enough. After several calls with Quarq, they agreed to replace it under warranty even though they felt the pre and post ride zero offsets were ok, borderline, but ok.



    So, this brings me to this Spring.



    I'm now setting up, in WKO+, 2 athletes. 2014 Indoor and 2014 Outdoor. For obvious reasons. Now, what I lose here is the ability to have my PMC give accurate slopes for 'me', cuz I feel the effects of Indoor and Outdoor. PMC Indoor vs PMC Outdoor.



    I've set my FTP in WKO+, for the 2014 Indoor Hardbeck, from recent indoor/tri position test results. So, the numbers are pretty low. But, based on some interval work on the trainer since, I feel (RPE) that I'm in the right zones.

    I've set my FTP in WKO+, for the 2014 Outdoor Hardbeck, from recent swag and predictable delta, about 15% higher. BUT, BASED ON TODAY'S RIDE...4.5HRS AT .87 and a TSS of 267. wth? Really, don't think that an average semi competitive AG'er does 4+ hrs close to .9IF.


    Yet, if I swag my FTP outdoors number up any higher, I'm looking at a 20-25% difference, maybe more, between outside FTP and inside FTP. Come on, that's too big, isn't it? And, if I swag that outdoors number up then I have to swag that indoor FTP up, too. I 'might' be able to do 12'/15'/18'/20' intervals using a slightly higher indoor FTP but not much more. Just being real, here.



    This issue is the one of the two most important pieces of the puzzle that I'm working on. I do believe that it had much to do with my frustrating races in FL and Wisc. (Tho, don't get me wrong, I'm always 'happy' just to get to play and finish!)



    At this point, without any huge races looming for me until Fall of 2015, I'm going with this strategy until I know better....Find that accurate indoors FTP/do interval work on the trainer based on this/riding outside is just for lung busting hanging on group rides/ roughly 10wks out from the 2 oly's I'm doing this year, I'll go outside and do a specific piece of road that should give me some idea of what outdoor numbers I should hone in on for the 10 wks leading up to and during the race.





    So, same topic as the guys above, just sharing thoughts and welcoming feedback. Maybe some of my points, maybe some of your feedback, will help the next guy.


  • Sooooo.... I was just looking at all the charts on GC....and I had been having some "Issue" with the display on my PM ....but it recorded everything just fine.... so, I had 4 "rides" from my out door ride the other day....(soon I'll have a few more). I created a second rider profile just for OUTDoors initially because I didn't think I was getting good data. I did have to clean up a couple dropped seconds and a couple Power spikes 2k + watts that threw off the CP charts....but after that....surprisingly consistent with INdoor numbers. Not enough and not steady enough to make power offset swag but it did show very similar CP curve and VO2 numbers and 10min SS effort (I did mostly short light to light PIs and a few 2-3 mile SS's but waited between for slower riders). I think if the meter display issue is resolved I can start to get some good equivalency and luckily -at this point- seems consistent to within at least 10% of indoor #s.......more to follow!
  • @Chris, concerning indoor vs outdoor in WKO. I simply change my power levels in the upper right corner to reflect my FTP for that day. This is useful s I have a number of FTPs ... Indoor, outdoor @ seas level, outdoor @ altitude, road bike, etc. It takes about 30 sec or less to key in the requisite FTP, which I only do if it is different from the current one. That way, I can have one continuous graph for PMC and all other charts.

    I try not to fiddle with my FTP too much (other than an altitude discount), unless I have an actual specific test to go from. I don't test that frequently, recognizing that once I get into spring/summer, my FTP isn't going to change that much, and most workouts will tolerate a range of +- 5% and still provide the requesite benefit.
  • Al,

    I like that idea of keeping one 'athlete', and inputting the appropriate FTP for the circumstances of the day. But, when I do that, I don't understand what I have to do to keep the date for that day only. Seems that the 'effective date' window is always greyed out. And, once I hit save (not sure if that's the key or it's something else similar), it changes all the workouts in the calendar. This doesn't come as a surprise to me, makes sense, I've just never figured this little thing out.

    Left Arrow vs Rt Arrow vs Effective Date. Obviously, a little nuance that could make my life (tri life, that is) a little easier. Missed this in the in-service. Any tips?

    This may sound like a stupid question, but, remember...there are no stupid questions, just stupid people who ask questions.
  • Al, correct me if I'm wrong, I think I figured it out with help from http://www.trainingpeaks.com/YAF_Gateway/forumhost.aspx?g=posts&t=41855



    In WKO+, Athlete Home tab, Power Training Zones window, hit options, now the effective date is changeable.



    SO....if today I were to ride in the tri position on the trainer: after the ride, I'd download the data, change the date to today's date (''and after'' per WKO+), make sure the the FTP is appropriate for indoor tri, hit enter, it'll save all metrics based on that day's FTP.



    Tomorrow, if I were to ride my road bike outside: I'd download the data into the same 'Athlete', change the date to the day of (''and after'' per WKO+), make sure the FTP is appropriate for outdoor road, hit enter, and it'll save all metrics based on that particular riding setup.



    Right? my only reservation (and this will get better once I do this a few times) is that ''and after''. I guess this is moot if I'm changing this every time I change riding styles?



    @ others: what does this have to do with Power- Trainer vs Road? By making these changes into WKO+, I (we) can monitor progress/build/fatigue under one 'athlete' regardless of indoor vs outdoor, tri vs road. Because, by making ride specific FTP changes (manually, by me), WKO+ will do the rest and make the necessary changes to TSS, IF, CTL, ATL, TSB, etc (basically, the impact on my body) for that day's ride, thus eliminating the need to create multiple 'athletes' in the log.

  • @ Chris - that's what I do. Yes, as long as you make the appropriate FTP change at the time you enter the data, the "and after" is not an issue.

    One caution - when I first started doing this 3 years ago, and wanted to go back and change my data to reflect different FTPs (the issue was altitude adjustment), I needed to start from the beginning of the data set and make the changes going forward. Going backwards didn't work.

  • K, I'll just add a note in the comments that I'm making these changes from here on.

    After enough data goes in there, it'll work itself out.

    Thanks for poking me to look into something I should've done a long time ago. That's kind of what this year is for...to pay attention to alot of the detail that I've been 'skimming' over for the past 4-5 years.
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