What about Gradient Lag?

Not this time!  Although normally you would be correct that this was the place.

under the menu

System -> Altimeter there is an Auto Cal. On setting. I’ve got mine turned on. I think I’ve noticed a message come up sometimes when I start that it is calibrating.  Other than that not sure when and how it works.  I have noticed though that rides tend to be more accurate now. My 1030 was definitely over and my 800 and 1000 under.  In Strava you can use the elevation correction feature also. 

How do you do this?

"In Strava you can use the elevation correction feature also."

I don't see how this can be done on my mountain bike activities on the Strava website or in the app on my phone.

Great!  Thank you! 

On my last ride, I gained 81 feet by using the correction!  I'll take whatever help I can get!  

The post ride grade correction is based on DEM topo data. It will not be accurate where there are bridges and road cuts. Take a ride that includes crossing a bridge of a reasonably deep valley. and look at the elevation data with and without grade correction enabled.

I can tell you that Wahoo does consider 10-15 seconds normal as I have talked to then about the same issue with the ROAM.

Just an interesting footnote to the grade conversation. I was on my gravel bike today doing a four mile climb that varies between 4 and 9 percent with heavy tree cover, switchbacks and close in terrain. I normally ride with the Garmin speed sensor but forgot to switch it to the wheels I was using. I anticipate the usual grade delays but was surprised to see grade jumping all over the place. That is when I realized the speed sensor was not there and speed was fluctuating between 0 and 15 mph when I was probably doing 6 - 8 mph. Random speeds yield random grade delayed grade reporting. 

I wonder why Garmin don’t use the gyroscope to measure the incline. Calibrating it using the GPS and altimeter in the same way they do with speed for speed sensors. The gyroscope on a phone gives instant feedback (try the iPhone level app). Seems obvious but I think this is the first Edge device to have a gyro so let’s hope it’s on the roadmap. 

bbrannon said:

The post ride grade correction is based on DEM topo data. It will not be accurate where there are bridges and road cuts. Take a ride that includes crossing a bridge of a reasonably deep valley. and look at the elevation data with and without grade correction enabled.

My experience with GC's post ride correction is that it doesn't replace the barometric data but rather adds a "slow" correction to it to account for drift and offset. e.g. On a loop ride, without correction the starting elevation might be off and the ending elevation different from the start.  With correction, they are correct, and the ride profile looks the same.  Total climbing a descending for the ride only changes a little.  I'll admit, I haven't looked specifically at a ride with a big bridge like you describe.

OK, one setting that seems to help reduce the lag, is to select recording data every 1 second. Did a side-by-side with the old 1030 yesterday and the 1040 was closer, but still delayed.

Setting for data recording