Calibration is off for first 5-10 minutes

[Guidob]

Every few months I see that the data for the first 5-10 minutes is off. I appear to have developed extraordinary strength and my power numbers are way up. Then by the later part of the ride they get back closer to normal.

I have not recalibrated or changed anything from the previous rides. I just turned it on and went for my normal morning ride. I have attached 2 files. One is the original file showing an average power of 420 watts for the first 7 minutes and then a second file after running Analyze Check Calibration. The power dropped to 208 W. What could be causing the issue? It's a bit frustrating since I upload the data to Training Peaks and every once in a while I see the power curve jump up and then when I look, I don't believe it makes sense. I know that today, I did not go very hard in the first 10 minutes so just over 200 makes sense.

Thanks

[Velocomp]

How is your Newton mounted on your bike? What is happening is that the tilt offset is incorrect at the beginning of your ride. This suggests that your mount has moved (rotated). Either the mount is not tightly attached or, possibly, your handlebars have rotated a bit.

[Guidob]

It's using the K-edge mount. It is rock solid, hasn't moved. I have seen the same exact issue a few times over the past year using the original Newton mount, but that was also rock solid and hasn't moved.

[Guidob]

Reading your comment about tilt calibration off, Is there something in the firmware that could cause it to reset/recalibrate itself at what might be an inopportune time, for example on initial power up? I am 100% certain that both the mount and my handlebars haven't budged one bit. However, is there some kind of trigger that might cause the firmware to recalibrate itself at the wrong time? My Newton always goes from my bike to my desk where it gets plugged into my PC and then back. If for some reason the firmware resets tilt calibration while it is on my desk that could explain this. Or could it reset tilt while I am putting the Newton back on the bike. I often turn Newton back on right before or while I am remounting it. That lets me see in a few seconds if it has found the right sensors. I have had a few cases where I powered it up and it did not find the speed sensor resulting in no data until I shut it off and restarted it or forced it to search again.

[Velocomp]

The other thing that can affect tilt is if the bike wheel spins when you're not riding the bike. For example, you put the bike on a mechanic's stand and spin the wheel, or you put the bike on the back of your car and the wheel spins.

The safe thing to do is, at the end of the ride, do a Trip Reset, then turn off the Newton. That will preserve the final tilt setting and also prevent the setting from being altered.

[Guidob]

I don't think anything like that has happened. Looking back at the last week, the bike was either being ridden or has gone a very short distance from the front door to where it hangs in the basement. It seems that for some unknown reason it has decided to recalibrate itself such that it is off for the beginning of the ride.

[Velocomp]

If you walk your bike to the basement with the Newton turned on, that would be enough to throw off things a bit.

Turn your Newton off immediately after your ride ends and all will be well.

[dmwelk]

If you walk your bike to the basement with the Newton turned on, that would be enough to throw off things a bit.

Turn your Newton off immediately after your ride ends and all will be well.

John:

I have been experiencing this same issue. I have noticed that my power typically runs high for the first few minutes of my ride. Initially i didn't think much of it because I usually ride from my house and I have a hill once leaving my driveway but have noticed once i level out the power is abnormally high. Couple of questions I have is, does the grade of the surface effect the initial angle reading once the PP is turned on or off. My house and garage sit at a higher elevation, so typically I walk my bike out of the garage onto the cement slab exiting my garage and now I'm facing downhill maybe at -1% or -2% grade, then I typically turn on my bike computer and PP. This also goes for when I get home from a ride but just the reverse, now I'm facing uphill at the same location when I turn my PP off. So is the PP remembering the angle it was at when turned off and this is effecting the power when turned on for the next ride until it re-calibrates? Also sometimes I have to carry my bike down some steps. So my understanding from your previous post is, if I turn the PP on and carry the PP down 3 or 4 steps and bump the front wheel causing it to spin a little that could cause an issue with the initial angle and power readings? If this is the case, do I need to turn off and on the PP on a level surface and that will remedy this? Otherwise once it gets past the initial 5-10 minutes of a ride it seems to be reading correctly.

[Velocomp]

If you are moving your bike around after the ride then PP readings can be thrown off for the first few minutes of the next ride.

My suggestion is to turn PP off at the end of each ride (5 clicks). This will prevent the tilt reading from being affected at the beginning of the next ride.