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RR#2: Check My Math on New Power Meter Delta!

Greetings Taper Bunnies!  

I did my final RR yesterday on the IMCDA course.  As luck would have it, my Power Tap Pro+ started to go titz up about three weeks ago (on second day of camp week!) so I find myself with new Garmin Vector Pedals.  Yes, if this is my biggest crisis in life I’m doing just fine. 

By the time I rounded up the pedals and got outside I had the opportunity to ride with both PMs for a whopping ONE ride.  Unfortunately during that ride the PT was, indeed, fritzing out (silver lining - validated the pedal purchase) so I didn’t get a solid comparison.  I didn’t have the opportunity to mirror my FTP test before RR#2 and honestly I REALLY shelled myself to earn the 225FTP in the last one so I’m not sure it would have been a good idea.  Reflecting today I still don’t think pushing a test in these last two weeks would be beneficial as I’m not sure what I would do with that data considering I think I have all that I need below.  My consolation prize is I’m betting when I eventually do retest my FTP will be higher simply based on the delta between the two power meters. And FWIW I have calibrated the pedals for this and every ride per the instructions and I do feel they are installed correctly as I’ve read the instructions and the DC Rainmaker review carefully.  



Anyway, I hit the course yesterday solidly chilled from a dip in the lake (!!!) and all seemed well and good until I got through the first loop at the planned effort of 160w.  I felt SUPER fresh, too fresh actually, and objectively I was a bit slower than RR#1.  So, I called an audible and bumped up the power to between 170 and 175w for the second loop.  This brought the entire ride to within a minute of the first RR (both about 5:55) at a HR that was 7 BMP lower than the RR#1.  Some of that could be the cooler temps or other variables like more aero setup, wind, training effect, etc. but HR is the main variable I have data on.  On the run I felt GREAT, much better than RR#1 actually where I couldn’t have imagined running another 20.  Yesterday it actually felt possible.  



Waking up this morning I’m feeling less sore than RR#1 I and I’m now a (wo)man with a plan!  I’ve left the FTP setting in the various sites/gadgets the same so as to not introduce ANOTHER variable but obviously this shows a very high TSS for RR#2.  Setting that aside for now, my intention is to ride the race shooting for the AP of 165 from RR#2.  I’ll be smoother without the large variation from lap #1 to lap #2 and if I’m really feeling sassy I may bump the last 2/3 (Hwy 95) of lap #2 to 170w.  My question is: Any input/counterpoints/things to consider that I haven’t noted above?  



Similarities: 

VI 1.01

Built power throughout the day

Nutrition protocol 



Differences:

PT Pro + on RR#1, Garmin Vector Pedals on RR#2

RR #2: Felt much fresher on the run

RR #2: Lower average HR

RR #2: Conditions more favorable



RR#1:

Training Peaks: http://www.trainingpeaks.com/av/3DF3HHFSE5UTNZINBK3IUP6TIQ 

Garmin Connect: http://connect.garmin.com/activity/505263154 

Strava: http://www.strava.com/activities/144489268 



RR#2:

Training Peaks: http://www.trainingpeaks.com/av/FHXPW4JOD5LJUBC4VDJHP5ZUIA 

Garmin Connect: http://connect.garmin.com/activity/522007080

Strava: http://www.strava.com/activities/154261732



 

Comments

  • Options
    Jenn ...I assume you're trying to figure out, "What power/watts should I target for race day, given this one ride with my new PM?" First off, set aside the subjective info, how you felt, how well you ran, etc, as you are in a different form/fitness place than you were three wks ago. Next, set aside HR for the same reason.
    I dont know if you have access to the TP graph, Mean Maximal Power; I only use PC v 3.0 of WKO+, and have it my suite of analytics. Anyway, the 5 hour figure for mean maximal power in this well executed RR Close to race day on the course is probably the best proxy you have for what IF/power level you should be riding at.
    FWIW, dividing that number (5 hr MMP) by 0.7 would give you a SWAG of your current FTP with that new PM system.
  • Options

    @ Al great info, thanks so much! 

    I do have access to that graph and it indicates 168w at the 5 hour mark and I've attached it.  That is within 3 watts of the 165 I was considering so it's good that you came to the same conclusion via a more objective method.  

    If the FTP SWAG holds up that will put me at 240w which is about a 6+% difference.  Seems like a lot and not a lot at the same time... 'tis what is it!  

    Appreciate your insight!  

  • Options
    Jenn-- The 2 powemeters could be VERY different in terms of readout for the same effort into the pedals, so you need to dial in to your NEW power meter in very short order. A week ago I had to send my SRM back to have the batteries replaced and have it recalibrated. I threw an old powertap on my bike and went out for my 5 hr ride on Saturday. A week earlier I had a NP of ~250W for a very similar ride and this Saturday it was 214W!!! A didn't actually look at my screen much since I didn't trust the early numbers I was seeing and simply rode as hard as I normally do (RPE). Looking at Strava, a few of my long segments (think ~30 mins segments) were within a few seconds of what they were a week ago. And my total avg speed for the ride was almost exactly the same as the week prior, if anything it was a tiny bit faster this week under very similar conditions. Bottom line is that I rode almost exactly the same, but had a power output at the end that was almost 14% lower. I know I didn't get 14% weaker in 1 week and my times show that I put just about the same effort into the pedals.

    With all that said, what should you do...? At a minimum, the Power you put out in your RR#2 is where you can ride at in your race. Likely, you could even ride a few watts higher. If you rode for ~6 hrs at an NP of 167W (with and AWESOME 1.012 VI) then you can certainly race there given how good you felt on the run (you have validated that effort with your RR#2). If it were me, I'd target 170W (after your initial settle in period) and see how you feel after 3 hours and re-adjust if necessary. BUT, I would do a short bike workout to try to "validate" this FTP number soon (like tomorrow if possible). You still have 2 weeks until the race. And you likely have something like a 3x6' at FTP on your schedule for this week. If you use 170/0.7 = 243W as your "new Powermeter FTP", and modify this workout to do a 1x12' and 1x6' at this 243 number, you should have a pretty good "feel" if you can hold this 243 for 12' or not (or even do a 1x18'). from that judge whether your FTP is "probably" a little higher or lower than 243W number. But the reality is, who cares what your new FTP is... The real question is what can you ride for 6 hours at and still have a good run. 167W (Vector) was within 2 mins of your RR#1 at 160W (with Powertap). So I think it's pretty safe to say that those numbers are pretty close to equal on the two different power meters. So try to hit 165-167W if you want to be a "little" conservative and aim for 170-175 if you want to "push the envelope" a little bit. Then use your experience to adjust in the last 3 hours as you feel appropriate.
  • Options

    Ah, MORE sage advice, thank you John!  Duly noted and I will certainly try to validate the power figures this week.  The plan for race day also feels very smart.  THANK YOU!!!

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