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Please help with calibration across 2 bikes
Posted: Fri Sep 20, 2019 2:49 pm
by Etupes25
Hello,
I would appreciate your checking my calibration across my road bike and my mountain bike. I am at my wits end after mulitple calibration rides. I take extra precaution in the road for the calibration (no traffic, no wind gust, no turns or significant slope), and it is the same for both bikes.
After the calibration, and based on power zones data from calibrated indoor bike and heart rate zones (150bpm LTHR and 250W FTP)
- the road bike seems calibrated OK, maybe under reporting power in the higher range (zone 5). At least I can get a heart rate at threshold level with a power reading consistent with my FTP.
- the mountain bike seems to be always vastly exaggerating power in the lower range in particular (zone 1 and 2). When my heart rate is in zone 1, the power is around 185W (high range of zone 2). It doesn't make sense. I would expect more like 135W or something like this.
I have attached 2 rides, one for the road bike and the other one for the mountain bike. Could you please check them?
Re: Please help with calibration across 2 bikes
Posted: Sun Sep 22, 2019 6:15 pm
by Velocomp
Both bikes are well calibrated.
Where are you riding your MTB? If it is not on soft roads, then Crr is too high, which would cause watts to be too high.
Re: Please help with calibration across 2 bikes
Posted: Mon Sep 23, 2019 2:18 pm
by Etupes25
Thank you for your fast answer!
For both rides, I was riding on the same type of road surface (asphalt). Typically I would ride the MTB on gravel, fire roads and easy single tracks.
Do I need to keep the Crr as is and count on a more accurate power when I effectively drive on gravel? Or do I need to lower the Crr and count the dynamic Crr feature to give me the right power when I drive on gravel?
Re: Please help with calibration across 2 bikes
Posted: Mon Sep 23, 2019 7:37 pm
by lorduintah
I would think the most reasonable calibration reduces the unknown factors as much as possible - meaning that for a MTB riding on the surface where you are going to use the bike seems most appropriate. You might be able to take the MTB profile and improve that after a few controlled rides on the right surface - likely to do more than just one or two rides that are out.back on that kind of terrain (and maybe even average the values you find.) Just a suggestion, but there are a few variables in the puzzle. John may have better suggestions.
Re: Please help with calibration across 2 bikes
Posted: Tue Sep 24, 2019 11:36 am
by Etupes25
That makes sense and I will experiment with out and back rides. It is important to me that LTHR and FTP are consistence since I consider training in that range most important.
The question remains about the Crr since it is manually set in the profile. Options:
a) use Crr = 0.006 and count on dyn Crr for MTB terrain
b) keep Crr = 0.008, forget about accurate readings on smooth road but get good readins on MTB terrain
c) use coast downs to get to the proper Crr? Not sure on this one
Re: Please help with calibration across 2 bikes
Posted: Tue Sep 24, 2019 5:24 pm
by Velocomp
Etupes25 wrote: ↑Tue Sep 24, 2019 11:36 am
That makes sense and I will experiment with out and back rides. It is important to me that LTHR and FTP are consistence since I consider training in that range most important.
The question remains about the Crr since it is manually set in the profile. Options:
a) use Crr = 0.006 and count on dyn Crr for MTB terrain
b) keep Crr = 0.008, forget about accurate readings on smooth road but get good readins on MTB terrain
c) use coast downs to get to the proper Crr? Not sure on this one
Use a) On rougher roads dynamic Crr will increase the frictional coefficient automatically.
Re: Please help with calibration across 2 bikes
Posted: Tue Sep 24, 2019 6:49 pm
by lorduintah
I am wondering how many think and rely on the power values that come from any power meter, not just the PowerPod-AeroPod family as a means to summarily say something along the line - I worked hard and I know I worked harder on this last ride - or took it easy.
Seems to me that with just about any calibration that could be considered adequate - and left alone (i.e., not constantly tweaked or re-evaluated) while doing more rides - would not provide a good idea of relative ride quality. I have found the PP V3 to be pretty darn reproducible when it comes to getting it calibrated. I have varied a number of riding patterns during the calibration - except where I did the calibration ride. This tells me the basic dynamics are stable. The sensors and responses are stable.
If they are so stable, then whatever calibration you may have stored can be relied upon to yield a measure of your ride effort and quality after a review of the subsequent rides and their performance relative to when the PP was calibrated.
If after a series of training rides, I think you can seriously trust that for the same route ridden over a period of time, you can expect Power values to improve (and times!) as your abilities and conditioning improve. If you spend all your time searching for the absolute best calibration, you are not using the PP for the intended purpose - getting to be a better cyclist. IMHO.
Re: Please help with calibration across 2 bikes
Posted: Thu Oct 03, 2019 12:55 pm
by Etupes25
Well said. Since I do many training session in the threshold zone, it is important for me to have consistent power readings across the 2 bikes. I am not too worried about lack of accuracy of the power readings, but I need consistency across the 2 bikes.
After I change manually the CRR in the MTB profile, do I need to redo the calibration ride or just send the updated profile back to the device?
Re: Please help with calibration across 2 bikes
Posted: Thu Oct 03, 2019 5:10 pm
by Kcblair
Yep, same here. I'm using my PP on 4 bikes, and the numbers seem to be very consistent. The numbers I get, give me a starting number to improve on, not how accurate that number is. Although, I have done some testing, (see GCN on Youtube, how to test your power meter), the calculated power is very close to what the PP is producing (1-3%). I'm a happy consumer. KB
Re: Please help with calibration across 2 bikes
Posted: Fri Oct 04, 2019 1:55 pm
by Velocomp
Kcblair wrote: ↑Thu Oct 03, 2019 5:10 pm
Yep, same here. I'm using my PP on 4 bikes, and the numbers seem to be very consistent. The numbers I get, give me a starting number to improve on, not how accurate that number is. Although, I have done some testing, (see GCN on Youtube, how to test your power meter), the calculated power is very close to what the PP is producing (1-3%). I'm a happy consumer. KB
You're using your PP very well (and on 4 bikes too!) to help you improve. That's great.
Too often, "accuracy" is the red herring that deflects the conversation way from the central requirement of a good power meter: consistency across the many different kinds of environments in which a power meter must operate.
There are a lot of reasons why our products offer arguably superior consistency compared to conventional power meters. And accuracy arguments can likened to the question: is the outside temperature right now 75F or 76F? The practical answer is: Who cares...I just want to know if it's getting warmer right now!
Re: Please help with calibration across 2 bikes
Posted: Fri Oct 04, 2019 2:09 pm
by Velocomp
Velocomp wrote: ↑Fri Oct 04, 2019 1:55 pm
Kcblair wrote: ↑Thu Oct 03, 2019 5:10 pm
Yep, same here. I'm using my PP on 4 bikes, and the numbers seem to be very consistent. The numbers I get, give me a starting number to improve on, not how accurate that number is. Although, I have done some testing, (see GCN on Youtube, how to test your power meter), the calculated power is very close to what the PP is producing (1-3%). I'm a happy consumer. KB
You're using your PP very well (and on 4 bikes too!) to help you improve. That's great; you'd have a very tough time moving a DFPM across all 4 bikes...
Too often, "accuracy" is the red herring that deflects the conversation way from the central requirement of a good power meter: consistency across the many different kinds of environments in which a power meter must operate.
There are a lot of reasons why our products offer arguably superior consistency compared to conventional power meters. And accuracy arguments can likened to the question: is the outside temperature right now 75F or 76F? The practical answer is: Who cares...I just want to know if it's getting warmer right now!
Re: Please help with calibration across 2 bikes
Posted: Fri Oct 04, 2019 5:47 pm
by Etupes25
Etupes25 wrote: ↑Thu Oct 03, 2019 12:55 pm
After I change manually the CRR in the MTB profile, do I need to redo the calibration ride or just send the updated profile back to the device?
Re: Please help with calibration across 2 bikes
Posted: Sat Oct 05, 2019 10:17 am
by Kcblair
Velocomp wrote: ↑Fri Oct 04, 2019 2:09 pm
Velocomp wrote: ↑Fri Oct 04, 2019 1:55 pm
Kcblair wrote: ↑Thu Oct 03, 2019 5:10 pm
Yep, same here. I'm using my PP on 4 bikes, and the numbers seem to be very consistent. The numbers I get, give me a starting number to improve on, not how accurate that number is. Although, I have done some testing, (see GCN on Youtube, how to test your power meter), the calculated power is very close to what the PP is producing (1-3%). I'm a happy consumer. KB
You're using your PP very well (and on 4 bikes too!) to help you improve. That's great; you'd have a very tough time moving a DFPM across all 4 bikes...
Too often, "accuracy" is the red herring that deflects the conversation way from the central requirement of a good power meter: consistency across the many different kinds of environments in which a power meter must operate.
There are a lot of reasons why our products offer arguably superior consistency compared to conventional power meters. And accuracy arguments can likened to the question: is the outside temperature right now 75F or 76F? The practical answer is: Who cares...I just want to know if it's getting warmer right now!
Thanks John,
I'm not a pro, so I don't care if my FTP is 127 vs. a pro with 1000 or what ever. But it is good to know, that the PP is as accurate as possible . So, soon a 5th bike will be setup for the PP, got the speed sensor, waiting on the out front mount. KB