21 and 20

Temps in the high 20's again. The cold really drains the energy out of me. I kept on trying to shift from my 21 to an easier gear, but 21 is as high as my cassette goes. I may have been in my 20 for a total of 5 minutes tonight. The rest of my ride was spent grinding away on my 21. Slow, slow, slow. 30/16.0