Calibration on a MTB with unlockable front shocks

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dabaracus
Posts: 23
Joined: Thu Jul 08, 2010 9:26 pm

Calibration on a MTB with unlockable front shocks

Post by dabaracus »

Hi All,

I have a GEN III wireless pro and i have been using on my roadbike with no issues for a couple of years, and i am having some issues calibrating to my MTB, it doesnt have lockable forks, so i am having troubles with the Cal ride, coast downs and some of my rides are stating that they have a bad tilt. Is there a particular technique of positioning on the bike that i can use that will give a better calibration. I am not so concerned with the power numbers, more the consistancy of the numbers.

Dave
Velocomp
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Re: Calibration on a MTB with unlockable front shocks

Post by Velocomp »

MTB with flex shocks are difficult for the iBike. The changing position of the frame causes problems for the tilt sensor

1) Do not do coast downs

2) Do a cal ride, and do the best you can to ride on a level, smooth road. Don't move around on the bike while on the ride

3) If you can get a good cal ride, then you will be able to use your iBike. Please note that your wattage averages, say over a 30 second period, will be ok, but your instantaneous wattages won't, due to the flex frame problem.
John Hamann
Ratman
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Re: Calibration on a MTB with unlockable front shocks

Post by Ratman »

Also, you may not be able to use a crr typical of many low-pressure mtb tires. I don't know if a Gen III is designed the same way, but on a Newton, when trying to use a crr which results in the fric value exceeding 25, the Newton forces the fric value down to a default value, in my case 6.555. This results in a large, systematic underestimation of rolling resistance, which is an especially significant component of power during off-road riding.

The fric value override occurs even when the Issac software's "Check Calibration" recommends that a fric value higher than 25 be used...
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