Further questions await Chris Froome on the 21 steps to hell

Bourg d’Oisans, late afternoon, July: we looked each other in the eye and swore it was not a race. Then, after the last clip of the pedals, the last symbolic sip from the water bottle, the last deep breath, we turned into the first of the 21 switchbacks that kick start the ascent of Alpe d’Huez.

And that’s where the race began. There are several ways to cycle a bike up Alpe d’Huez, that crazy iconic road which rises from 722m to 1,860m in a mere 13.8km, with an average gradient of 8.1 per cent. Like the marathon, it’s not the distance that kills but the pace: in our case, after five hours in the saddle already, the faster the pace the shorter the distance made perfect pseudoscientific sense. So we raced each other to the top, and prayed it wouldn’t kill us.

The pro cyclists call it the 21 steps to hell, although truth is Alpe d'Huez is not the longest or even steepest climb in the Alps. Yet its place in cycling folklore – and particularly the Tour de France – has made it the yardstick for any rider who likes to measure themselves against mountains.

Only we were riding for charity, not the maillot jaune, and without any measure of heart rate, power output or, definitely, watts per kilogram. And what helped get me to the top first, we all agreed about 55 minutes later, was having the skinniest arms and legs.

Later, back down at Bourg d'Oisans, sipping on a lager, we had great fun comparing our times with those of the pros. Depending on interpretations of the various Tour stages, Marco Pantani still holds the three fastest times ever clocked on the 13.8km ascent, his 36 minutes and 50 seconds, in 1995, being the "record". Lance Armstrong is the next fastest rider, then Jan Ulrich, Floyd Landis, and so on – all of whom now have a very large asterisk next to their names.

None of this, naturally, we took seriously, given the range of variables involved, not least the amount of erythropoietin (EPO) racing through their veins. Still, sport has always found a way of measuring historical performances against each other, while attaching various levels of significance to them, and cycling is no exception.

Advances in performance technology have made this an even bigger deal, even if some people will always question the technology's validity. When heart-rate monitors first became a popular measure of physical effort, in the 1990s, Sean Kelly famously asked: "But do they measure suffering?"

Only now, after the first three mountain stages in the 2015 Tour, has this performance technology and associated data suddenly reached unprecedented heights of significance, at least in trying to establish whether or not Chris Froome is wearing the maillot jaune for reasons other than simply having the skinniest arms and legs. Or indeed whether or not those skinny arms and legs should be propelling him to such heights in the first place.

Some people, particularly the backroom members of Team Sky, insist that this heightened obsession with rider data is mere pseudoscience that is being unfairly turned on Froome. Others, particularly the coaches and scientists who have been observing this sort of rider data over time, are adamant that it provides a telltale sign of doping creeping back in the peloton.

The problem with rider performance data such as this is that it’s not an exact science. Still, the most common measure is on mountain climbs, using the length and gradient of a stage segment, the time taken to climb it, the weight of the rider and his bike, then estimating rolling and wind resistance, before calculating a figure in watts per kilogram.

Anything above 6.5 watts per kilogram is considered to have broken into superhuman territory, and it’s around here that Froome, according to some interpretations, is now operating.

One of the loudest interpreters of this (and also of Froome's leaked data from the 2013 Tour), and of whether it should be deemed a sign of doping or not, has been Antoine Vayer, who formerly worked with the Festina cycling team in the 1990s, and thus needs no further introduction: "If I saw this from one of my riders, I would say, 'Go back home, I don't want you on the team'."

Yesterday, L'Équipe also published a long article headlined "Froome, les raisons pour la malaise " – "the reasons for the bad feelings" – which referred not just to his crushing ride up the La Pierre Saint Martin on Tuesday, to take charge of the Tour, but also to his Team Sky escort to the finish on Plateau de Beille on Thursday. There, and despite riding into a headwind, both Froome and team-mate Geraint Thomas eclipsed several of the previous fastest climbs up the 15.8km ascent, including Armstrong's best from 2002, plus several other rides achieved at the height of cycling's doping problem.

Now, after the Pyrenees, comes the Alps, and while Froome continues to look into the eyes of his doubters, “because I ride clean and Team Sky rides clean”, things may soon reach the stage where the questions over his performance data become impossible to ignore, at least without the sort of full transparency that the likes of Vayer are calling for.

Because next Saturday, on the penultimate stage of the Tour, Froome will turn into the first of the 21 switchbacks that begin the ascent of Alpe d’Huez, and begin another unavoidable measure against the likes of Pantani, Armstrong, Ulrich and Landis.