As I progress through the year I have noticed a change in my limitations. For example, early in the year during our weeknight hammerfest my heart rate would max and I would become very short of breath. This would lead to getting dropped. Now I can hang longer and have better times. On the ride (and during a race) my breathing remains comfortable and HR manageable, but my legs just become fatigued and/or don't have the strength to either hang with the fast group or continue after bridging a gap. This drives me crazy because I feel comfortable otherwise. What is the best way to improve in this area?