Following the route of Le Tour, and therefore the Etape du Tour, the ascent of the Tourmalet involves 4606 feet of ascent give or take a few feet here and there, the gradient varies of course but is generally around 7-8%. If I make assumptions of my planned body weight at the time of the ride and my bike weight it is a simple matter to calculate the duration of the ascent at various wattages.
Based on the training I'm doing, which is specifically geared towards long climbs, and my past experience I know that I can ride at an average wattage of around 240-250W for long periods, I have in the past during hilly sportives ridden at a normalised wattage of 260W for 5 + hours. So, if I average 240W for the Tourmalet climb that calculates out as an ascent time of one hour and 23 minutes which I would be perfectly happy with. My plan is to keep out of the red on the climbs when riding The Tour because I'll need to be able to do repeat climbs like this time after time, to go too hard at them would be totally counter-productive.
Well all that looks fine and dandy to me, the numbers look perfectly manageable, then of course there is the wind and the rain and the....... snow? Surely not, but look at stage one of Paris-Nice!
CTL now climbing just nicely:
ATL: 78.0 CTL: 67.3 TSB: -11.5