One of the harder things to get used to is the concept of two hard days on the bike in a row is a huge benefit to training. Research has shown that alternating hard and easy days can help with your training as a basic concept. Of course, the key is to go HARD and then super EASY to recover. And if you are out riding for fun and not worried about quick gains, this is a great way to improve over time. However, for endurance sports that have multiple day efforts or one day efforts that training for is not productive (i.e. 50-100 mile running races aren’t possible to train for by running 50-100 miles in a single day regularly); the best way to create the endurance necessary is to double up hard effort days.
At first pushing out multiple hard days in a row can feel overly draining and counterproductive. Once your body starts to adapt, it can become relatively easy to string together 2 or more hard days of training in a row. I often see quite a bit of growth once this adaption happens and riders will begin to show even better power on the 2nd day. Of course, the trick is to plan for these training periods in your overall year/month/week. Then to plan the equivalent level of recovery to make sure the gains are developed over time.
The best way to get there is to grow these days slowly and think about each day differently. I like to alternate interval work with endurance work and a bit of a mix of steady state work on the endurance day. This allows the body to work different systems; all the while working in some more difficult days in groups. Both days having long distance. Additionally; during the week there are great opportunities for pushing 2 days in a row of hard interval efforts on shorter time frames.
I’d encourage riders to try this and slowly build up until that 2nd day in the mountains feels comfortable. Once this type of endurance is hard wired into your body; you will be able to taper into your key events/races and then really feel fresh.