It's cold out. A techie is going to stop by to fix a computer problem. I decided to ride on Zwift. I chose the London Loop map. My intention was to do two laps depending on how the body responds. I got my gear working, suited up and hopped on. The legs felt pretty good to start. It took about 12 minutes to reach the base of Box Hill. When the climb started, I began modest. Purposely holding back. The climb went quick. I was in and out of the saddle. Mostly out. I was doing between 2 and 3 W/kg. Higher while out of the saddle, lower while in. It was mostly rinse and repeat, somewhat interval-like. I reached the summit in around 11 or 12 minutes. From there, I headed back into town. I pushed through the tunnel riser. After crossing the finish for the first time, I was feeling good enough to do another lap. The legs were warmed up, so the initial ride to the base of the climb went quicker. I was ahead of my Halo replay. When I reached the base of the climb, I increased the tempo to about 3 W/kg. I was near that wattage for most of the climb. With about half way up the climb, my right knee started to complain. So, I backed off a bit. Other than that, I used the same approach. In and out of the saddle. I made it to the summit about 20 to 30 seconds quicker than the previous lap. I took a few moments to recover and then made my way back to the start / finish. I put in a dig through the tunnel riser. After crossing the finish, I shut it down and cooled down till the HR reached 112BPM. Concentration was good. My patience was in check. Balance and form felt pretty good. Ailments, some right knee soreness on the last climb. The inner right glute was hinting on soreness but didn't escalate. Gear worked flawless. Nutrition was good. I drank most of my sport drink. Other notes, there were over 4000 riders when I hopped on.