- Endurance. If you lack endurance, you will slow down throughout the race and perhaps bonk. To get better at this, ride lots and drink a sports drink.
- Muscle power. If you go backwards up hills, in sprints, on flats, or in any steady effort, you may lack muscle power. To get better, practice that effort (1 min., 5 min., or 20 min.) which you are bad at, over and over.
- Recovery. If you take an inordinate amount of time to get the heavy feeling out of your legs from an anaerobic effort, recovery is your weakness. To practice this, do workouts with short recovery, walking the line between repeatable hard efforts and puking. I'm not an expert, but to get the bad juices out of your system is a complex process that involves your muscle cells, liver, and probably more. I think that's why racing can sometimes leave you feeling like you just pounded 10 shots of tequila.
I just did a workout and I can tell you that number 3 is getting me down. Please pass the tequila.