That points are obtained from the track recorded in the GPS, which gathers them automatically with an approximately cadence of 50 point per Km (depending on the groove variations and direction changes)

The distances crossed in each raise and descent (1%,5%,10% etc..) are calculated from that points. It is calculated the representative % above the total, the total meters raised and descended, the average rates of raise and descent, the total Km and the distribution of the raising sections.

A mathematical standardized formula is applied. It gives a punctuation between 0 and infinite, This punctuation is 100%. Objective. No subjective value such as groove conditions, time needed, climatic factors or physical form are taken account.

This index is useful to know the difficulty grade of different routes compared among them. As subjective factors are not taken account, the value takes different importance depending on everyone.

For example, an IBP valued 60 will be a very hard route for an inexperienced person, quite easy for someone who has a medium training and very easy for a professional

Another formula to use IBP is to know the difficulty of a new route drawn in the map manually with a program such as: oziexplorer © or compegps ©. As long as track points have the height, it will be valid to obtain the index.

However, as we will commit mistakes when we mark the points in the map and other own mistakes of the same map or from the height …., the index obtained that way won’t be as reliable as the index obtained with real information from the GPS.

It is important not to confuse the grade of difficulty of a route with the grade of suffering and effort.

Suffering effort of a rote

physic state

climatologic conditions

race pace

IBP

The state of paths in mountain bike routes (MTB)

The state of paths (without taking into account the climatology) could be considered as an objective value, it could be that someone had asphalted surface or they had levelled recatholes …etc. anyway we can think that tracings will be always similar.

Logic make us think that area state influences in the hardness valuation of a route in a critic way

Someway it is true that studies from more than 100 routes between people of different levels have shown us that the influence of that point is minor than expected.

When we were fitting this factor, the personal perception of the hardness of that factor isn’t very different from the result ( a 10% approximately), so we have decided to mediate that value to make IBP index simpler, as it would be difficult and complicated to create an scale of “area states” which everybody could understand the same way. It possibly would create discrepancy that wouldn’t help us in the comprehension of the index.

An explanation could be that the cyclist adapts the level of effort-suffering to the state of the area. A raise of 500 meter at 10% in a width and plain path could be done with a mediate plate at 10km/h. For example, this 500 meter at 10% in a tight path with stones and recatholes could be done with the minimal development at 4 or 5 km/h. Time employed will be the double, and suffering will be a bit major.

Another case are raises with a difference of level and a hardness of the surface as big as the most little development doesn’t allow you to control the suffering. In this situation you can reach the limit of pulsations.

A simple way to explain the influence of the surface state would be:

While you are who controls your pulsations, the surface state influences little. When surface is who control your cardiac pace then the surface state starts to become more important.

Mediating the surface state value, the result of IBP index is adapted to the majority of the habitual routes. It is obvious that a hypothetic route where the 100% of the raise is made in groovy and irregular surface, mistake margin will be higher.

However, as the formula is made with that value, in the next professionalized versions, we’ll be able to use it with more precision.

Mistakes in the tracks

The IBP system detects and corrects automatically mistakes of height in the tracks

Meters accumulated of raise and of descent

The total accumulated meters of raise and descent that IBPindex shows is strictly the sum of the GPS records. GPS receptors tend to accumulate some meters more of raise and descent due to sway.

The modernest receptors are, day after day , more precise and so they accumulate fewer mistake.

Some programs (including intern programs which manage the devices) make a correction of this mistake by eliminating the accumulated meters, If some longitudinal meters ( 5m usually) are not crossed. We think that this correction can also falsify the reality. If we imagine a plane path with continuous unevenness of 0.5m ( a very usual fact in MTB) the correction will give us 0 accumulated meters although we have surely raised many of them.

In IBPindex we don’t make any correction, as we don’t know if information comes from a receptor with a big or little mistake, a wavy or a plane path, we think that information given from the GPS will be more exact day after day.

IBP Index Team