So today I went on a long ride (for me). It was a 40 mile loop with 2736 ft of elevation gain. I had done this ride about four months ago and I had to stop probably 5 times during the climb due to not getting enough oxygen. My heart rate was approximately 140 - 165 this time around and I had zero problems with breathing. This time however my legs felt like lead jelly. On one hand it was exciting that I saw gains in my cardio fitness but I just don't get the legs thing. By the end of my ride, I was cramping in my hamstrings. I have never had to deal with cramping this far. I generally ride 60 to 70 miles per week, mixing in flats and small hill climbs. Sometimes more miles, sometimes less. The only thing I can think of is the temp difference. Today 80 and my first ride was around 55 degrees. I think my main thought was to really focus on increasing my base miles and continue to lose weight before trying something like that again. What thinkest you? Oh, for the record I'm 6'2 270. Thanks all.