21* when I left the house for 2 hours of 40min tempo/5min recover/5x3min@300w/3min recovery. This ended up being 1.5h with 30min tempo and 4 intervals. What really killed me was the cool down between intervals..just locked up my legs. I was so cold and numb that I just couldn't take it anymore. This ride had a JF (Jens Factor) of 4.5.