Fortunately, there’s a way to train for steep mountain passes even when there aren’t any climbs in your area. Use these tips to become a better climber with or without the convenience of having Alp d’Huez in your backyard.
The following is an example of an interval set you can do to train for a sustained climb of about an hour:
As you get more comfortable with this type of effort, increase the duration of the interval and lower the number of sets. Complete 2 sets of 30 minutes, eventually moving to one interval set just under your FTP for one hour, which will be close to the effort you'll experience on race day.
If you're going to do these efforts on the road, try to find an area where you won't have to deal with a lot of traffic stop lights. While not ideal, you can also do these efforts in a controlled environment such as the indoor trainer.