Improve your endurance base to become a better climber
Your endurance base is very important to become a good climber. Many cyclists train too hard so their power output at their anaerobic threshold is relatively low compared to their maximum power output. These cyclists reach their threshold very fast, but can sustain high intensity efforts longer. However, if you want to become a better cyclist or climber you want to improve your threshold instead of being able to ride longer above your threshold.
Even for people without power meter I can explain this by using power. Someone with a threshold of 250 Watts will go into the red when he produces more than 250 Watts. If this person starts climbing at 275 Watts he can sustain this effort for 3 minutes, after that he has to slow down. You're not a better climber if you can sustain the same effort for 4 minutes. If you want to improve your climbing abilities then you have to increase your power output at your threshold, for example from 250 Watts to 280 Watts. Now, you can climb at 275 Watts without going into the red. You can sustain this pace a lot longer.
To improve your threshold, you need a good endurance base. You can improve your endurance base by doing the majority of your training sessions at a very low intensity. When you have a decent endurance base you can improve your threshold by doing some more specific and harder training.
Weight plays an important role for cyclists who want to climb better
Another important factor that plays a role in climbing is your weight. When you're climbing the greatest resistance comes from gravity. If you are heavier climbing a hill or a mountain will be harder. Every extra kilo will costs you about 30 seconds at a 10 Km climb.
When you start working on your weight, make sure you lose weight gradually. If you lose weight too quickly or if you lose too much weight then you will also lose muscle mass. Don't save on your carbohydrate intake, this is the main fuel for your body during high intensity exercise. To lose weight you always have to burn more calories than you consume.
Train in the hills or mountains
Training in the hills or in the mountains helps you to become a better climber. You will get used to the position on the bike and pedalling with a different cadence. On the flat most cyclists choose for a cadence of 85 rpm or more and pros usually choose for 90 rpm or more. Uphill it's a different story, then the pros choose a cadence of 80 rpm to 90 rpm depending on the gradient of the climb, and amateurs of 70 rpm or higher.
Simulate climbing training on an ergometer
If you cannot train in the hills or in the mountains and you want to improve your climbing than you could simulate climbing workouts on an ergometer. This can be done by doing some sub-threshold blocks of a few minutes with a cadence of 70-80 rpm. You can increase the intensity of these blocks gradually.
Without a good endurance base this type of training can do more harm than good. Start with a few short blocks of 2 minutes sub-threshold and make the blocks longer every two weeks. Note that the recovery of this type of training takes 24-48 hours.
Climb at a constant pace
If you're riding in the hills or in the mountains it is important to find your own pace. You can make more progression by doing some longer efforts just below your threshold compared to hard hill sprints. On short climbs a lot of cyclists start too hard and have to slow down halfway or at the end. When you go too hard, too early, on a climb you will pay the price. For example, when you start a climb at 600 Watts and you have to slow down to 200 Watts, you can still finish the climb with an average of 250 Watts. However, you will notice that you arrive at the top of the climb at the same time with a rider who constantly climbed at 250 Watt. You are totally blown up at the end of the climb and the other rider is less tired.
Improve your cycling technique: standing versus seated climbing
When you’re seated your pedalling is smoother and your power is a bit more regulated. Most riders in the WorldTour peloton will stay seated for the majority of the time. They are only climbing out of the saddle when attacking, tackling steep pitches or attempting to break up the rhythm.
Standing on your pedals doesn’t cost you more energy when you consider the higher power output that you’re able to produce. However, extended standing while climbing must be practiced to optimize your technique. For heavier riders, who have to support more weight, it might be more efficient and economical to remain seated while climbing.