You only need to place a mountain bike and road or triathlon road bike side by side to realise that they’re very different animals. A road/tri bike is designed to traverse smooth tarmac as rapidly and efficiently as possible. A mountain bike on the other hand is designed to get you from A to B across impossibly difficult and rugged terrain, with speed as a secondary consideration. Given these fundamental differences, you might assume therefore that mountain biking is wasted on road cyclists and triathletes seeking better performance. A closer look at the evidence however tells a different story.
How could the addition of mountain bike training to your weekly routine help road cycling performance? One obvious answer is that when icy winter conditions on the road make riding downright dangerous, a knobbly-tyred mountain bike can take you safely off-road. And while it’s very different to road riding, there’s a solid argument that some riding is better than none. Then of course there’s the ‘a change is as good as a rest’ scenario; getting off road can bring some much-need variety should boredom set in on the road. More importantly however, there are some sound physiological reasons for occasionally swapping those skinny road tyres for some fat knobbly ones…
When it comes to triathlon and road cycling, aerobic power is absolutely critical for performance. For triathletes in particular, since the biggest proportion of time in an event is spent on the bike, aerobic fitness on the bike should be a prime concern. Given that road cyclists tend to spend more hours per week on the road than their mountain biking counterparts, and that road cycling lends itself more easily to structured training such as intervals or pace riding, you might assume that road cycling is the only game in town for building high levels of fitness.
Rather surprisingly, there’s been very little research comparing the fitness of road vs. mountain bikers but in one study, researchers compared the fitness of seven internationally competitive mountain bikers with seven pro cyclists who also competed internationally(1). In a 30-minute time trial, the road cyclists were able to sustain a slightly higher maximum power output than the mountain bikers (433 watts vs. 411 watts). However, the body mass of the mountain bikers was on average just 65.3kgs compared to 74.7kgs for the roadies, giving the mountain bikers a superior peak power-to-weight ratio (6.3 watts/kg vs. 5.8 watts/kg) and a superior power to weight ratio in the 30-minute time trial (5.5 watts/kg vs. 4.9 watts/kg – see figure 1).
The road cyclists could sustain a higher wattage over the 30-minute time trial (top); however, the mountain bikers had a superior power-to-weight ratio (watts/kilo – bottom).
In plain English, over any course containing any gradient (ie virtually all courses), the mountain bikers would have been significantly faster. This aerobic superiority was confirmed when measurements of VO2max (aerobic power per kilo of bodyweight) were made; the mountain bikers scored 78.3mls of oxygen uptake per kilo per minute while the roadies scored 73.0mls/kg/min. In short, adding in mountain biking into your training schedule needn’t equate to poor quality training or time wasted – as these results clearly show
As well as helping to maintain or even build fitness, the use of mountain bike training offers other potential benefits. For example, studies have shown that when it comes to balance and balance control, road bikers have better visual processing capabilities whereas mountain bikers tend to have better proprioception – ie an awareness of body position in space. The best overall measures of balance control however were found in cyclists who did both types of biking(2). Mountain biking requires (and is also associated with) better development of power and upper body strength than road cycling. This explains why studies into off-road triathlon have found that performance tends to drop off more rapidly with advancing years compared to road triathlon(3) (strength and power decline more rapidly than endurance with age) and also why female triathletes perform relatively less well in the MB sections of off-road triathlons(4) (women tend to be naturally less strong than men).
Want to add some mountain biking into your training schedule? Here are some tips:
References
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