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TrainerRoad virtual power check
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 2012-11-11 6:02 AM |
Regular 181  |  Subject: TrainerRoad virtual power checkI've been using TrainerRoad for a bit and realize that the virtual power readings can't be taken for exact power readouts. It is just a guide to measure your progress if all variables are the same during each session. However, I am still curious if my readings are accurate to real world power. When I am doing a session, and say I'm putting out 200 watts of power, my speedometer registers about 19.7 to 19.9 mph. If I ramp it up to 240 my speed goes 21 mph. Now, if I take this data and compare it to power charts or power calculators like this one http://bikecalculator.com/it seems like everything matches up nicely. So does this mean that my power outputs might be pretty darn close to those achieved if I had a fancy power meter? |
| 2012-11-12 12:17 PM in reply to: #4493573 |
 over a barrier | Subject: RE: TrainerRoad virtual power check It probably means bike calculator and virtual power are using similar algorithms |
| 2012-11-12 9:56 PM in reply to: #4493573 |
Master 1484 Sedona, AZ | Subject: RE: TrainerRoad virtual power check I'm leery of any program or device that estimates power without strain gauges. Can you borrow someone's powertap for a few days to verify? The outputs might be fine for training purposes (consistency), but I wouldn't go throwing the numbers around as though they are valid (accuracy). |
| 2012-11-13 6:00 AM in reply to: #4493573 |
| Regular 181 | Subject: RE: TrainerRoad virtual power check Strain gauges? Didn't know that's now they did it. But no, I don't know anyone who has a power tap or something like that. I am super curious about my power output since I want to race in some crits or what not this summer. But I get your point, you need to look at how much effort you are putting on the bike in relation to the speed. I guess I will call around to bike shops to see if anyone has one I can hop on and use. Thanks. |
| 2012-11-13 9:54 AM in reply to: #4495821 |
| Member 194 | Subject: RE: TrainerRoad virtual power check +1 VirtualPower is not a power meter, so you can't use it to compare to anyone else. The rolling resistance difference between tires/pressure/tightness on the trainer can be huge. Like 40 watts on some trainer tires at different tensions. It's only useful for training purposes. Keep your setup consistent and your numbers will be consistent. |
| 2012-11-15 9:49 AM in reply to: #4495821 |
Pro 4054 yep, | Subject: RE: TrainerRoad virtual power check MonkeyClaw - 2012-11-12 10:56 PM I'm leery of any program or device that estimates power without strain gauges. Can you borrow someone's powertap for a few days to verify? The outputs might be fine for training purposes (consistency), but I wouldn't go throwing the numbers around as though they are valid (accuracy).
Totally agree with this. i'm mainly using Trainer road as a way to train harder and push myself. I'm taking the power output with a grain of salt. IE I did a 8 min power test and came out with an FTP for 201. Which I know is WAYY too low and I had the resistance too high. How do I know my FTP isn't 201, since the week before I was riding with a friend who had a power meter next to me. Going the same speed, same course (flat) and we were doing around 230-240 watts at a conversation pace.
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| 2012-11-15 9:50 AM in reply to: #4496315 |
| Pro 4054 yep, | Subject: RE: TrainerRoad virtual power check npearson99 - 2012-11-13 10:54 AM +1 VirtualPower is not a power meter, so you can't use it to compare to anyone else. The rolling resistance difference between tires/pressure/tightness on the trainer can be huge. Like 40 watts on some trainer tires at different tensions. It's only useful for training purposes. Keep your setup consistent and your numbers will be consistent. My point exactly I had the trainer too tight and it dropped my FTP probably around 30-40 watts. Considerable drop, but as long as you train with the same resistance it should help. |
| 2012-11-15 2:09 PM in reply to: #4493573 |
Extreme Veteran 2263 Ridgeland, Mississippi | Subject: RE: TrainerRoad virtual power check Use the estimated watts from Strava. It's way more accurate! |
| 2012-11-15 6:06 PM in reply to: #4499204 |
Master 1484 Sedona, AZ | Subject: RE: TrainerRoad virtual power check Dlaxman31 - 2012-11-15 7:49 AM Totally agree with this. i'm mainly using Trainer road as a way to train harder and push myself. I'm taking the power output with a grain of salt. IE I did a 8 min power test and came out with an FTP for 201. Which I know is WAYY too low and I had the resistance too high. How do I know my FTP isn't 201, since the week before I was riding with a friend who had a power meter next to me. Going the same speed, same course (flat) and we were doing around 230-240 watts at a conversation pace. No no, you have it all wrong! You're supposed to say your FTP was calculated at 400W, but you don't think it's much over 350! |
| 2012-11-15 11:03 PM in reply to: #4493573 |
Pro 5361 | Subject: RE: TrainerRoad virtual power check well- I wouldn't compare speed numbers on a trainer to speed on the road. TR does a virtual power calc based on the correlation between trainer speed and power for each specific trainer model. Some are more consistent (unit to unit as well as over time and temp) than others. One of the specific reasons why I bought the KK Road Machine is that it appeared to be well respected for it's power curve consistency, and this seems to be the case. Now- that said, I've got a Powertap on one bike and use TR with a speed/cadence sensor mostly with my other bike. I think the virtual power is maybe 5-10 watts higher than my powertap power (but it really depends on how fresh I feel that day). Hard to say as i've never recorded both at once and compared. (can you?- I think that it just picks up one of the power sources???) Thing is, it kinda' does matter if you're using Golden Cheetah or Training Peaks and your CP curve jumps up 10 watts every time you hop on the trainer. Overestimates your TSS. |
| 2012-11-16 11:21 AM in reply to: #4499912 |
| Pro 4054 yep, | Subject: RE: TrainerRoad virtual power check MonkeyClaw - 2012-11-15 7:06 PM Dlaxman31 - 2012-11-15 7:49 AM Totally agree with this. i'm mainly using Trainer road as a way to train harder and push myself. I'm taking the power output with a grain of salt. IE I did a 8 min power test and came out with an FTP for 201. Which I know is WAYY too low and I had the resistance too high. How do I know my FTP isn't 201, since the week before I was riding with a friend who had a power meter next to me. Going the same speed, same course (flat) and we were doing around 230-240 watts at a conversation pace. No no, you have it all wrong! You're supposed to say your FTP was calculated at 400W, but you don't think it's much over 350! Ha |
Sounds good to me. I'll be there soon enough.|
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