MTB settings for powerpod

[petrs99]

Hi there:)
So far I tried few rides with the Powerpod on the roadbike and it seems pretty fine so far (thank you for checking the calibration). Now I finally received the sensors for the MTB (speed & cadence) and I tried to set up the new profile for the mountain bike. I was a little tricky as there was no option for MTB in Isaac and also the tire pressure I was not sure what should I put in. I finished with the Best accuracy option and went for a cal ride (it is attached).
Then I went for a pretty windy ride on some gravel roads, not so technical, pretty ok, but the wattage seems really really high to me, especially compared to the HR, which is also visible in the files.

Can you please check what should I change in the setting or is it fine like that for MTB? Thank you for the support! Cheers

[petrs99]

Or.. in best case, I would like to learn the Isaac magic you are doing, too. Is there any way I can learn more about all the things you are checking? So I can also review my rides alone and not steal your time for that. Would be great to learn. Let me know, thanks John.

[Velocomp]

I think your calibration is incorrect. You had considerable head and tail winds during your cal ride (you can see this in your cal ride download).

I would do a new cal ride, ideally under calmer winds, but if not possible then riding faster. This will improve the accuracy of the readings on your tail-wind portion.

You MTB rolling resistance settings look a bit high, but let's get the wind readings right before attacking that.

Remember that on an MTB, for highest accuracy you'll need to have the suspension locked up on the uphills.

[petrs99]

Hi John,
Thank you for your answer, yes indeed it was (again) very windy outside. I thought it might be problematic, but I tried it anyway with the cal ride.
Ok, I will do another calride soon and hopefully will be better. I will post it soon. Should I change something in the profile setup ( wheels, pressure, road conditions etc) or should I keep it as standard?

Ps. I had the suspension fork locked out.
Thank you for your support! Petr

[petrs99]

Hi John,
finally we had some decent weather to repeat the calride. I did as you suggested, it was not so windy and I did go faster than last time. However after it calibrated itself, I still think that the wattage numbers were too high as I know how should my HR and feeling be when I pedal 250w or 300w. But you will probably see that from the files itself pretty clear.
Let me know what you think or If I should change something, thank you.

[petrs99]

Ok, I think it will be the CRR - rolling resistance setup. Original crr setup was = 0,01701. And what I have find on the internets should be for my tire = 0.00624.

When I tried to put this into the Tweak CdA, Crr & Cm in Isaac, then it gave me more reasonable Avrg. watts.. but I dont know, I am no expert at this at all.
Additionally they have there that the values are measured for (Speed: 29 kmh / 18 mph, Load: 42.5 kg).. http://www.bicyclerollingresistance.com ... eskin-2015

I hope you will bring some more clarity on that for me:) Cheers

[Velocomp]

This ride is well calibrated, but in the last 20 minutes of it there is evidence of your suspension (or PP) moving around.

Make sure things are tight and you'll be OK.

[Velocomp]

Adjusting Crr to 0.006 will knock things down a bit.

[petrs99]

So you mean I should not change the Crr for 0,006 and keep it like it is?

[petrs99]

And yes, that part with a lot of braking etc. Is that I was just playing around, doing some wheelies and Sagan stuff so I think it is because of that. PP is tight as possible as on the photo below:-))

[Velocomp]

that will do it...

[petrs99]

If anyone will read it later or for a future reference - I will change the Crr value in the profile for 0,007, which gave it Riding tilt of -0,7 % and Friction of 11,276.

I will give it a try, but seems more precise than the previous Crr of 0,0170.