Differences in interval wattages

[GWPOS]

I just did some 2x20 intervals and have a discrepancy between the 2. They were both started at the exact same place and no wind changes. My second interval came up with a higher avg. power than the first when clearly it was slower. I think it has to do with the auto tilt correction but was wandering if maybe something can be tweaked in my profile to keep this from happening. If you notice the first 4-5 min. of the 2nd interval the unit is off on the slope. Maybe my tilt is slightly off causing it to give a higher wattage for those first 4-5 min. My Gen3 did the same thing except it under calculated watts instead of over calculating. Strange???

iBike_07_05_2012_1731_22_Miles.ibr

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[rruff]

When you start a new file, of course you need a good tilt if you want accurate data for the first 5 minutes.

[GWPOS]

I understand that, but this ride was one continuous ride, so I am trying to figure out if there is something I can change in my profile to make my 2nd interval right, or do I have to wait for 5 min then do it. I know we have been through this before with the Gen 3, but I wanted to make sure it was not something I did in my profile. If not I guess it is one of the limitations of the IBike power meters I will have to live with.

[Velocomp]

Sit tight while we look in to this.

[GWPOS]

I am holding tight. Just a follow-up on things I have discoverd on my own. For this workout I posted, I took the first interval @ 3.45 miles in length and checked elevation gain. I then compared it to othe days where I did intervals in the exact same location using my Gen3 unit. On the ride I posted it says I had a slope of 5.99% and 1107' of climbing. Should be more like 1185' (I used Garmin connect, Veloroutes, and Map My Ride to check elevation gains). I also checked slope of my previous rides and all of them avg out to around 6.5%. I keep getting lower elevation gains, which is giving me falsly lower wattages. Will do some 2x20 tonight and see what I get.

[Rick]

When you start a new file, of course you need a good tilt if you want accurate data for the first 5 minutes.

What's this about new tilts for new files.? I thought a good tilt was "once and done" for the unit??

[GWPOS]

He simply meant that if your tilt is off in your profile that the first 5 min of data is messed up. After that the autotilt correction kicks in in the Newton and fixxes the tilt for the rest of the ride.