I ride bikes, but run sometimes.

I find the lopsided nature of ability between the two breaks the calculator for HR zones.

Any advice?

Best example of what I’m getting at is that it takes a pretty ridiculous skeletal stress or lactic feeling running to achieve a similar HR zone to cycling.

The muscular and lactic tolerance in one sport versus the overall aerobic ability makes it feel....weird.

Just go by RPE when running instead?