Mountain biking workout

I do both road cycling and mountain biking. The Outdoor Cycle workout algorithm seems to work well for road cycling in terms of calories burned, heart rate, etc. But with mountain biking, the outdoor cycling option significantly undercounts the amount of activity and often pauses, especially during the toughest parts of a mountain bike run (where you're working very hard but not going very fast). Would love to see a specific Mountain Biking workout option where the algorithm is more closely tuned to the activity, maybe based more on heart rate, elevation changes. Anyone else have this problem with the two types of riding?