The title may be a bit misleading as the word 'harder' can be interpreted in different ways. I am writing this article with the perspective that it is harder to learn and be a 'good' mountain biker than to be a 'good' road biker. (The amount of time needed to be an accomplished mountain biker is much longer compared to road biking).
In road biking, you are generally working with a flat surface which make life a lot easier, and a lot smoother!. Once you have the basic turning technique down, you really need to work on conditioning your cardiovascular system to ride longer and more efficiently. Aside from entering a turn 'outside - inside - outside', you really do not have to learn any other significant skills. Most of the time you will be sitting on the bike grinding an uphill road or on a descent that requires an equal weight distribution across both tires.
In mountain biking, you are faced with many factors that you need to take into consideration while riding a trail, especially if it is one that you have never rode before.
One of the main differences between the two types of biking is an uneven surface. As you roll over an uneven surface, you will need to adjust your weight forward and backwards to maintain attack position.
There are obstacles of various sizes and shapes and you will need to determine what speed will be best to roll over or jump the object and what technique you may need to implement. On a trail, the usual suspects are tree roots, rocks and ruts. This is all within a few seconds of seeing the obstacle and your experience and judgment can be the difference between continuing down the trail or rolling down the side of a hill with a broken wrist.
What type of trail are you riding? Is it sandy? Loose dirt? Compact dirt? Gravel? Pebbles? Lots of fallen leaves, branches, sticks, twigs? You should take into consideration all of the above trail conditions and apply the appropriate speed and techniques.
How are the conditions? Is it damp? Muddy? Dry powder? Just after a rain? Is there morning dew on the trail? Misty? Even if you are familiar with your local trail, it changes as the weather and season changes.
Is your equipment setup correctly for the trail that your riding? Is your front / back tire pressure optimized for the trail? How about the tire that you are running? Does it have enough grip to take that turn at 35mph?
These are the reasons why I believe it is much harder to become a 'good' mountain biker than a 'good' road biker. On that note, will it be hard for you to become a good mountain biker? It depends on what level you would like to get to. If you are a cross country racer, maybe your goal will be to finish in the top 10 in the beginning class. Maybe one of your goals is to ride a technical trail all the way down without dabbing? It may be just keeping up with your friends.
These are all factors you need to interpret while riding down the trail which makes it much more difficult than Road biking. I will go on to say that if you are new to mountain biking and do not receive any type of advice or assistance, you will learn by trial and error and may have quite a few bumps, bruises, scrapes and maybe a laceration here or there. Hopefully you will not break any bones...
Keep riding and you will get better each time as you will gain more and more experience on the trail. Learn to become agile on your bike and flow with the trail. If you have a full suspension bike, allow the front and rear shocks to do most of the work. Try to work on one technique each time you go out, like going around a switch back faster or timing that small drop for that perfect two wheel landing.
Ride safely and I'll see you on the trails...
