Some Newbie Questions

[fwbmorison]

Hello,
I have just done a few rides with my new PPv3 and have a few questions:
I notice the problem with very high power the first few minutes of a ride and now understand that the device must be oriented exactly the same way every time and have made the adjustments to the mount so I can do that. However, on an out and back ride, I stopped for 10 minutes at the turn around point, nothing touched the device while the bike was parked, but on restarting I had 2 or so minutes while the power reading seemed amount 25% high. Any ideas why that would occur?
Also, on the same ride, I noticed that power readings seemed high descending hills. This was especially the case on a descent averaging about -5%. I read another post that said this could be an issue, but no explanation why or how to remedy it.
I ran the "check calibration" function from Issac on this ride thinking that might help, but the effect of the adjustments was to increase my average power by about 10W, when in fact, I think that the original average was about 10W too high. Also, the Calibration Check change the friction number from 9.758 to -173! I'm not sure exactly what that figure means, but negative friction does not seem very realistic, so I did not send these adjustments back to the PP. Do these figures make sense?
So far I have only paired by speed sensor. I want to also pair my cadence sensor. How can one tell that both sensors have successfully paired (without going on a ride and then downloading the file)? Also, if I do that, do I have to do another calibration ride?
Thanks to anyone who takes the time to respond.

[fwbmorison]

One more (somewhat pedantic) question: Can I change the units in Issac to metric - I really have no idea what 20 mph is unless I multiply it by 1.6 to get a real unit!

[texbiker]

You can change from English to metric in Isaac in the upper right corner of the charts display screen.

[Velocomp]

Hello,
I have just done a few rides with my new PPv3 and have a few questions:
I notice the problem with very high power the first few minutes of a ride and now understand that the device must be oriented exactly the same way every time and have made the adjustments to the mount so I can do that. However, on an out and back ride, I stopped for 10 minutes at the turn around point, nothing touched the device while the bike was parked, but on restarting I had 2 or so minutes while the power reading seemed amount 25% high. Any ideas why that would occur?
Also, on the same ride, I noticed that power readings seemed high descending hills. This was especially the case on a descent averaging about -5%. I read another post that said this could be an issue, but no explanation why or how to remedy it.
I ran the "check calibration" function from Issac on this ride thinking that might help, but the effect of the adjustments was to increase my average power by about 10W, when in fact, I think that the original average was about 10W too high. Also, the Calibration Check change the friction number from 9.758 to -173! I'm not sure exactly what that figure means, but negative friction does not seem very realistic, so I did not send these adjustments back to the PP. Do these figures make sense?
So far I have only paired by speed sensor. I want to also pair my cadence sensor. How can one tell that both sensors have successfully paired (without going on a ride and then downloading the file)? Also, if I do that, do I have to do another calibration ride?
Thanks to anyone who takes the time to respond.

1) If you stop for an extended period of time PP will think you've stopped the ride for the day. It will start a new ride file when you resume (click the button to turn it on). Depending on what you were doing just prior to taking the break, it's possible the internal tilt setting will be a bit off. After you resume riding the calibration will fix itself in 90 seconds.

2) When descending many riders go into a slight tuck, in order to go faster. A tuck reduces your CdA; however, PP doesn't know you're in a tuck, so it assumes you are going faster because you are pedaling harder (more watts).

3) The "Fric" number is an internal parameter used by Isaac. That it changed by a fair amount in the Check Calibration item simply means that your PP has changed rotational position since your Cal Ride.

4) If you pair to your cadence sensor you will have to do a new cal ride (every time you do a sensor pairing, a cal ride is forced).

[fwbmorison]

Thanks John,
on 1) I didn't stop long enough for the unit to shut off and start a new ride, so it must have been something I did just as I slowed down.
on 2) I recognized that if I went into the drops that would create high power, but surprised that a relatively unconscious tuck, with my hands still on the hoods, could make such a difference.
And @texbiker - Doh! For some reason I expected that the other options to English would be Italian, Spanish and German. Thanks