Mountain biking and cyclocross are both difficult and painful sports. The physical skills you have already from mountain biking will help you do well in cross, but if you want to really excel there are a few easy but painful workouts you can do to help your body transition into a cyclocross racer.
The biggest difference between the two sports is the intensity level. Mountain biking is all about going fairly hard for a long time. The effort in a mountain bike race is fairly consistent over the course of a 2-3hr race, with a few bursts of power to get up a short steep hill or a technical section. A lot of racers will go into “time trial” mode, riding a nice steady consistent pace from start to finish.
A cyclocross race is much shorter, only about 40 minutes for women and an hour for men. The intensity level is higher, with most of the race spent at or above your “red zone”. It is one big suffer fest! Cyclocross is also about explosive power; being able to sprint out of every turn; being able to follow attacks, and being able to jump off the bike, sprint, and then get back on the bike without losing any speed. There are huge changes in speed and intensity during a cross race. Cyclocross is all about anaerobic power and the ability to tolerate high amounts of lactate in the muscles with very little recovery. The “time trial” mentality of mountain biking won’t help much in a cross race.
To get ready for cyclocross there are some great workouts you can do that will help you develop the fast twitch muscles and the explosive power you’ll need. One workout I like is called Microbursts. After a 20 minute warm-up, the workout consists of a 10 minute interval. During the interval you will do a 10 second sprint, a 20 second recovery, a 10 second sprint, 20 second recovery and so on for the full 10 minutes. Then recover for 10 minutes before doing another set. Each sprint should be done in the drops and as hard as possible. Sprint like you were attacking in a race. Heart rate won’t respond to such short efforts so don’t look to it as a guide. The microburst workout will help you develop high end anaerobic power and the ability to recover from repeated accelerations without blowing up.
Another great workout that helps develop the anaerobic power needed for cyclocross is the Kilo. Kilos are some of the most intense intervals I’ve ever done. You’ll need to find a flat stretch of uninterrupted road. Measure off a one kilometer stretch, marking the start and finish. This workout is most effective if done with a power meter. Get up to speed before crossing your “start line”. Once you cross your start line start your power meter. You want to go as hard as you possibly can for one kilometer. You are going for the highest power output over one kilometer. This effort is harder than the standard Vo2 interval. On a flat road with little wind it should take you around 1 ½-2 minutes to reach your “finish line”. Stop your power meter when you finish the kilometer. Now recover for 10 minutes. When you do your second one, try and generate a higher average power and a faster time for the same distance. This workout is exhausting and I recommend doing it only once a week.
Of course there are lots of other workouts you can do to help prepare your legs for cyclocross racing. These are two of my favorites and I’ve gotten great results from both. Remember, though, that it takes time and your legs won’t become cyclocross legs overnight. Give yourself a few months before you start seeing changes. It’s worth the time and effort!