A really good drill that will help your climbing is find a hill that takes at least 2-3 minutes to climb. Ride up it in your Vo2 max zone as soon as you gone about 2-3 minutes, turn around and ride down quickly, letting your legs spin for recovery and when you get to the bottom, repeat the process. Do 3 intervals, 5-8 minutes of recovery after the 3 and then do another 3