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Classification of the technical difficulty of the tracks
The described method of assessing the technical difficulty of trails for recreational use is the IMBA (International Mountain Bicycling Association) method, developed based on the international trail classification system used in ski areas around the world. Many localities with developed networks of mountain bike trails use this system. It is especially suited to mountain biking but is equally applicable to other types of users, such as bikers or riders. The final judgment on the trail is made by evaluating it according to the proposed grading criteria and combining that evaluation with personal judgment and input provided by users. The IMBA method of ranking trail difficulty can:
- Help users make “informed” decisions;
- Encourage users to use tracks suited to their technical abilities;
- Contribute to risk management and accident minimization;
- Improve the outdoor experience of a large proportion of users;
- Help with route planning and the trail system.
Criteria considered include:
- Track width > the average track width.
- Type of bottom of the track > the type of the bottom and its surface stability.
- Track slope (maximum and average) > The maximum degree of slope measured in % on the steepest section of the track, however, longer than 20m. The average slope measured over the entire length of the track.
- Natural and artificial obstacles on the track > elements that add difficulty by opposing progression. The height of each obstacle is evaluated from the surface of the course to the top of the obstacle. If the obstacle is uneven in height, the point at which it is most easily overcome is evaluated. Artificial trail obstacles (Technical Trail Features – TTFs) are objects that may be put in place to increase the level of difficulty.
In summary, the technical difficulty of the route relates essentially to the characteristics of the terrain to be encountered (both uphill and downhill) and constitutes of the route a kind of weighted assessment. In the presence of particularly challenging and dangerous passages that cannot be avoided (e.g., exposed), the evaluation of those passages may be extended for safety reasons to the entire route, regardless of their incidence on the total. Conversely, a trail rated as challenging overall may also include short technically difficult sections, as long as the difficulties are discontinuous (i.e., such that the biker can eventually reject the obstacle) and the danger contained. In this way, the biker will enjoy the opportunity to increase his or her technical level without, however, taking any particular risks.
The philosophy followed by the IMBA method for “technical” evaluation of tracks is summarized below:
- The system is focused on grading the technical level of the route and not on assessing the athletic effort required (physical exertion). In fact, it is not convenient to evaluate both types of difficulty with a single evaluation system. Consider, for example, a gentle and wide trail 35km long. The technical level of the track is low, but the distance imposes a high level of athletic exertion. The solution is to evaluate the technical level independently, clarifying the level of athletic commitment required through additional indications, such as length and elevation gain of the trail. The joint indication of trail length, elevation gain, and technical difficulty is simple to integrate while being easy for the user to understand.
- In order to arrive at the final score for each course, the course ratings given for each criterion (a course may merit the green circle in two criteria, but the blue circle in two different criteria) are combined with personal judgment. In fact, there is no prescribed method for arriving at the final score for each track.
- Tracks are evaluated relative to other tracks in the area. Indeed, it is not convenient to evaluate each trail individually, while it certainly is convenient to compare them with each other. This helps to rank the relative difficulty of each and will help users to select the most suitable track. A “black diamond” trail in one region may be rated “blue square” in another region. The rating is thus locally relevant. The evaluation of a route is not 100% objective. In fact, it is convenient to combine measurable data with subjective judgments to arrive at the final rating. For example, a trail may consist of several different sections by type of bottom: much of the trail is easy, but some sections are more difficult. How to evaluate the course? Using one’s personal experience, considering each element and selecting the rating that best fits the “style” of the trail.
- Characteristics outside the “objective” criteria proposed by the method are considered in the evaluation of a track. A wide variety of features may in fact contribute to the perceived difficulty of the track. For example,exposure. A rocky passage only a few tens of centimeters in height may appear to be a boulder that is difficult to overcome if next to it is a 100m drop into the void! Other features to evaluate are the wide view and the radius of the curves.
- No scoring system can be totally objective or valid in every situation and will have to be combined with common sense. Each track is therefore “looked at” with a careful eye, and input provided by other users must be sought before selecting a final score.
