Downhill power measurements

[rstrom]

I'm relatively new to the iBike and have some questions regarding it, the first one concerning what I see in this ride I did this past Wednesday. The ride was a hilly ride and what was most surprising is that according to the iBike the most powerful portions of the ride were on the downhill rolling section of the ride, not the uphill portions.

Uphill for 21+ minutes, 874' of elevation gain, 120' elevation loss, ave. power = 261w; normalized power = 286w

Downhill for 20 min, 155 feet of elevation gain, 935' elevation loss, ave. power = 288w; normalized power = 336w

Virtually all, if not all of my peak power and sustained power measurements during this ride are during the downhill and this makes no sense to me.

I have attached the file in case any one is willing and able to take a look at it and give me some insight.

Thanks much,

Robert

[Velocomp]

Your iBike hasn't been calibrated properly.

If you look at the bike speed/wind speed graph you'll see blue "flames" shooting up everywhere from your white bike speed. This means that the wind scaling factor is too high.

I've adjusted your profile so that average wind speed = average bike speed for this ride (this assumes there was no ambient wind during the ride). Your downhill watts are now normal.

I will email you the modified profile separately.

[rstrom]

Ah, but it was a windy day

I will work on recalibrating the unit.

[lorduintah]

John's point is that unless you only went one way (and never got back to starting point) the average wind had to balance out to some headwind and some tailwind. Your plot only shows (almost exclusively) you riding into a headwind.

Tom

[rstrom]

I went out on another calibration ride today. Hopefully this calibration ride is OK. If you (someone) could please take a look at the attached files to see if they look OK I would appreciate it. I am attaching the calibration ride, the extracted profile from the iBike after that ride, and the 27 mile ride that I went on after the calibration ride.

Please note that this was a pretty windy day.

The unit and the software are definitely very nice providing the user with LOTS of information and feedback but there is a definite learning curve here.

Thanks,

Robert