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Is there a new GC total ascent calculation?

Former Member over 15 years ago

The last three rides I've done show up on GC with a total ascent considerably lower than what TC shows, and lower that what GC showed for the same route on previous rides. Has Garmin announced any change in this feature?

I'm not objecting -- perhaps the new algorithms is better in some way. I'm also fully aware that there is no one right way to measure total ascent, except for very limited cases (i.e., monotonic slopes).

Here is the route that I ride when I am out at night, the last two times I've ridden it:

http://connect.garmin.com/activity/13391737
(1233 ft climb)

http://connect.garmin.com/activity/14557356
(867 ft climb)

All my other runs look like the first one, and the total ascent doesn't differ by more than 20 feet.

I'm just curious more than anything else.

0 GASTER over 15 years ago

Me too, one ride that has 1000 feet of slimbing on TC shows 400 on GArmin COnnect. Any ideas?

0 Former Member over 15 years ago

new algorithm is bad

I just did a short ride with my daughter.

http://connect.garmin.com/activity/15298611

It is an out and back ride, so obviously the start and end elevations should match, but are off by 140 feet. Ignore that; that is not my point here.

Calculating total elevation is problematic -- how small of a bump should be counted into the total? The smaller the bump one considers, the greater the total will be. However, we can be conservative and find just a few local minimums and local maximums and compute the difference of each maximum less the preceding minimum. This gets most of the climb, and ignores all the questionable smaller hills.

In the elevation map above, I count only the four most obvious hills. The self-reported altitude differences are:

1306-1242=64
1301-1175=126
1254-1148=106
1193-1082=111

In total, that is 407 feet of climbing, calculated very conservatively. TC reports 480 feet. GC reports 339 feet.

Something is broken with the GC total ascent calculation.