When I began to get involved in cycling in 1980, I was surprised to find that almost no cyclists, not even professionals, were in the habit of quantifying or evaluating their own performances in training or in racing. Everything was measured by subjective feelings and sensations or to specific race results. 

 

In fact cycling performance was and to a degree still is difficult to evaluate effectively. Chronometrical references and benchmarks are lacking for athletes to be able to gauge their own training or racing status and progress. 

Speed parameters, for example, are too much influenced by external factors such as wind, temperature, the course itself, tailwind from other riders etc. 

It is of course possible to obtain more precise information from individual time trial results, but these are nonetheless influenced by the course and the wind. Climbs, however, can give much more useful data, especially for grades in excess of 7-8%, since ambient conditions have less effect since speeds are much lower than on the flat. 

That is why I began by timing the climbs of the best professional riders during time trial climbs or finish sprints on grades. In order to be able to compare different climbs (which were nonetheless similar in grade and duration), I decided to measure the performance in each climb in reference to the height variation covered in an hour. 

For example, if the Colombian Lucio Herrera (one of the great climbers of the 1980s) took 29’30” to cover an incline of 830 meters, it means he would have covered the incline at a ‘speed’ of 1688 meters/hour.

 

I called this parameter Average Ascent Speed (‘VAM’ in its Italian abbreviation from Velocità Ascensionale Media). Of course, this parameter is affected by outside factors, especially wind, but it still allows for relatively accurate performance evaluation. 

It is also essential to consider the altitude of the climb itself. Climbing an incline of 800 meters at between 200 and 1000 meters above sea level is very different from an equivalent climb between 1500 and 2300 meters because of the reduced oxygen available at the higher altitude.