I "can't run more than a block" but I can ride my bike all afternoon. I've only experienced this a few times on long rides. This was back when I was riding qu

I "can't run more than a block" but I can ride my bike all afternoon. I've only experienced this a few times on long rides. This was back when I was riding quite a bit more than I do today - it took about 30-40'ish miles to get it. For reference this is on flat ground at about 1800 ft elevation. I'm not sure about running, but I would estimate that 3-5 miles isn't enough - maybe 10?