Yet another FTP estimation question



RapDaddyo

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May 17, 2005
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Originally Posted by bgoetz .

What if I put my bike on the computrainer and compared the numbers? Would that be a good way to check the calibration? Also how do I do a manual torque calibration vs the auto calibrate?
Also, my AP now seems reasonable (196 for RR and 283 for crit), just the NP is high (316 RR and 361crit). So you still thinking calibration issue? I suppose the data could still be suspect, I do use the "auto pause" feature could this also be screwing things up?
The CT comparison should reveal a large discrepancy, assuming you warm up your CT before comparing, but I wouldn't count on the CT revealing a small discrepancy (e.g., 10W). When I first got my CT, I compared the CT watts with my PT watts after warmup and using the CT procedures for setting press-on force and the rolling resistance calibration routine. I found that the CT was off by enough (although I can't remember the number now) that I decided to set my press-on force more precisely and not rely on the CT rolling resistance calibration routine. So, I machined an adapter out of aluminum for using a precision torque wrench to set the press-on force. That procedure allows me to get within 1-2 watts of my PT, but I have to change the torque force slightly as my tire wears. Also, I have run MAP tests for other cyclists on my CT and I have found huge variances in the amount of torque force depending on what tire they were using. When I say huge, I mean a range of about 40lb-in - 75lb-in, depending on the tire.
 

bgoetz

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Nov 25, 2010
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Well, did multiple stomp tests and it is spot on. Never got a single positive indication and the largest variance was -2.2%. Most of them were within 1%. This wAs using 22kg of weight.
 

RapDaddyo

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May 17, 2005
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Originally Posted by bgoetz .

Well, did multiple stomp tests and it is spot on. Never got a single positive indication and the largest variance was -2.2%. Most of them were within 1%. This wAs using 22kg of weight.
Sounds like your numbers are valid. I'll be interested in what your variance is between your CT watts and your PM watts, although note that this variance is likely not constant from tire to tire and even the same tire as it wears.
 

bgoetz

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Nov 25, 2010
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Yeah, that will be a rainy day project, lol Based on my high NP values in WKO I bumped my FTP to 350. Looking at the zones it was creating for 340, 350 seemed more appropriate. Particularly my L5 to L6 power, which would have only been 408, I have done many 5 min intervals on the computrainer at or above that. I even had a 5 min max of 385 during the race. So 350 bumped that figure to 420.
 

RapDaddyo

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May 17, 2005
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Originally Posted by bgoetz .

Yeah, that will be a rainy day project, lol
Based on my high NP values in WKO I bumped my FTP to 350. Looking at the zones it was creating for 340, 350 seemed more appropriate. Particularly my L5 to L6 power, which would have only been 408, I have done many 5 min intervals on the computrainer at or above that. I even had a 5 min max of 385 during the race. So 350 bumped that figure to 420.
Yes, that is what I meant before by it being self-correcting for training purposes. You will quickly see if your training targets are too high (or too low). Anyway, you've got some good power for racing. Have fun.
 

lanierb

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Aug 12, 2004
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Originally Posted by bgoetz .

Well, did multiple stomp tests and it is spot on. Never got a single positive indication and the largest variance was -2.2%. Most of them were within 1%. This wAs using 22kg of weight.
Nice! Those are some impressive numbers. You won't be Cat 3 for long.
 

bgoetz

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Nov 25, 2010
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I am actually not anymore, just got my upgrade Monday after my results from this weekend :D!
 

danfoz

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Apr 12, 2011
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Originally Posted by bgoetz .

I am actually not anymore, just got my upgrade Monday after my results from this weekend /img/vbsmilies/smilies/biggrin.gif!
Am I recalling correctly that you were a Cat5 at the beginning of last season?
 

bgoetz

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Nov 25, 2010
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Yes, my 1st race ever was March of last year. Since then I have accomplished more than I ever thought I would and am pretty sure I could have done more had I raced differently. Guess will see what I can do racing in the pro/1/2 field.