Trainer Road FTP test results (Page 3)

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2013-03-01 8:28 PM
in reply to: #4627579

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Subject: RE: Trainer Road FTP test results
DirkP - 2013-02-18 5:33 PM

I'm just getting into virtual power myself (can't make the $$$ dive into real power) and I just tested my first FTP.  My numbers came in a higher that I expected for an 8 minute Trainer Road virtual power test.

The number suggested by Trainer Road for my FTP suggests 328.  My weight is 72.6 kg which puts me at 4.5 watts per kg.  This seems outrageous to me.  I am not convinced I have that much power after only three and a half years riding and the first year I was pretty much blind (no idea what I was doing at all). 

The only other information I had to go on was an indoor triathlon, in March of last year, that had a 20 minute bike.  The ride was on a computrainer and I could see my average watts, 270, after the ride.  I could have ridden harder over that 20 minutes and had a some higher numbers but that's all hindsight.

Question: What kinds of things might I look for to be able to make sure these numbers are accurate? 

I am planning a 20 minute test later this week to check the numbers against the 8 minute test.

NameTimekJ/CalTSSNPPowerTargetHeartCadence
Workout01:00:007907227821918713897
High Cadence 100:01:00131211213202137109
High Cadence 200:02:00241202204202138111
Clearing Effort 100:01:00212321350342144110
Clearing Effort 200:01:00212327355351139106
8 Min test 100:08:0017216358358310161102
8 Min test 200:08:001791736937231016398

 



Nate from TrainerRoad.com here.

VirtualPower is not a power meter, so it could be off by a lot due to rolling resistance changes. With a gator skin tire, I'm about 20 watts high compared to my power tap on a kurt kinetic. On a trainer tire at 5 full turns, I'm dead on.

That being said, the curve can still be wrong. I think you e-mailed us, because I just got an e-mail from one of our guys that the magnet curve is wrong. We're going to get some more data from cycleops, but if anyone has this trainer and a power meter and has the time to run a couple tests that would help us out.

After we get this fixed, we can update your test.

For now, you can still workout with this curve. I think it's a fairly flat curve, and it looks like you did the 20 min test too. If you do workouts around threshold it should still be repeatable, which is what you want.

2013-03-01 10:20 PM
in reply to: #4642933

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Subject: RE: Trainer Road FTP test results

npearson99 - 2013-03-01 9:28 PM Nate from TrainerRoad.com here. VirtualPower is not a power meter, so it could be off by a lot due to rolling resistance changes. With a gator skin tire, I'm about 20 watts high compared to my power tap on a kurt kinetic. On a trainer tire at 5 full turns, I'm dead on.

Nate, thanks for chiming in on this thread. I can see how rolling resistance etc. might make a difference on the trainer. But is it the case that for a given coast-down rate, the resistance will be the same on the same trainer. E.g., if I went from Gatorskins to a trainer tire without changing anything else I might encounter different resistance, but if I adjusted flywheel tightness and/or tire pressure to yield the same coast-down rate, wouldn't that give me identical resistance? Thanks.

2013-03-01 10:37 PM
in reply to: #4643021

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Subject: RE: Trainer Road FTP test results
colinphillips - 2013-03-01 8:20 PM

npearson99 - 2013-03-01 9:28 PM Nate from TrainerRoad.com here. VirtualPower is not a power meter, so it could be off by a lot due to rolling resistance changes. With a gator skin tire, I'm about 20 watts high compared to my power tap on a kurt kinetic. On a trainer tire at 5 full turns, I'm dead on.

Nate, thanks for chiming in on this thread. I can see how rolling resistance etc. might make a difference on the trainer. But is it the case that for a given coast-down rate, the resistance will be the same on the same trainer. E.g., if I went from Gatorskins to a trainer tire without changing anything else I might encounter different resistance, but if I adjusted flywheel tightness and/or tire pressure to yield the same coast-down rate, wouldn't that give me identical resistance? Thanks.



Yes, as long as the slope of the curve is correct. This one might have a bad slope, we're looking into it now. But threshold will be threshold even if the curve is bad.

But if the curve is good, then as long as you keep everything consistent then you'll have consistent numbers, no matter the rolling resistance.
2013-03-02 7:46 PM
in reply to: #4643032

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Subject: RE: Trainer Road FTP test results

Nate,

Thanks for checking into this.  I have done both test, as you have already figured out,  but I have also found that I had a couple of things wrong for my set up.  First was an incorrect tire size (or at least I think it was) and then I didn't have the tension adjusted properly.  I am planning another test in about 2 weeks when I am into a recovery week (marathon training is leaving me a little beat up) and I shuld get better numbers them too.

BTW,  I have not emailed you guys about the problem.  I also don't have a power meter to use to test with either.  As you and other stated, I can use the numbers for training without making much difference other than not having a true power number and I can live with that.

I would appreciate knowing what you find out about the curve as you learn more.

Thanks again!

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