Climbing and time trialing are the two most difficult aspects of road cycling. When the road turns seriously up, drafting plays a very minimal role, as each individual's true ability is exposed.
The first mountain stage of any Tour de France illustrates this, as riders are spread out all over the mountains while each rider climbs to the best of his ability. The best climbers make going uphill look effortless, even though their bodies are in terrible pain.
What makes a great climber, especially in the mountains, is an excellent power to weight ratio.
Power to weight ratio has two components: first, the ability to ride for long periods of time at a Maximum Sustainable (MS) power.
Typically a top climber can ride at 10 percent or more above threshold power (or threshold heart rate) for 30 to 60 minutes.
Second, top climbers have a low enough body weight so that the MS power translates into an advantage going uphill. Having a high maximum sustainable power output will make an excellent time-trialist on flat roads where the main obstacle is wind drag.
To carry over this advantage to climbing, you need a low enough body weight in relation to your MS power. This is especially true on long and steep climbs.
On short climbs of less than five minutes, so-called "non-climbers" can still make it over with the front riders with their very high MS power even though they may have an inferior power-to-weight ratio, due to their heavier body weight.
Bjarne Riis, winner of the 1996 Tour de France, illustrated how much body weight can make a difference while going uphill. Riis beat the great Miguel Indurain in 1996. At the time of his win Riis weighed 150lbs (68kgs) and had a MS power of 480 watts while going all-out on a climb or time trial. This gave him an incredible power to weight ratio of 7 watts per kilogram (480 / 68 = 7). 7 watts /kg is widely regarded as the magic number in order to be one of the world's best.
Indurain had a MS power of 550 watts when going all-out, a much higher number than Riis. However, he weighed in at 176lbs (80kgs), 26lbs heavier than Riis! This gave him a power to weight ration of 6.8 watts/kg (550 / 80 = 6.8), 0.2 less than Riis.
Indurain's much higher MS power gave him the advantage in the time trials, where the main obstacle is wind drag. However, on the longest, steepest climbs of the Tour, this was not the case, as Riis' 0.2 watts/kg advantage made all the difference.
A few years before his Tour win, Riis's story was quite different. He was a good professional, nothing more. At the time he weighed 165 pounds (75 kg), 15 pounds more than his Tour-winning weight. Riis was slightly overweight for a pro cyclist and could lose some body fat.
With the help of a great coach, he not only lost 15 pounds (over a few years), but with a new, more scientific training program he was able to increase his MS power, making him unbeatable in the 1996 Tour.
Some cyclists are already at 4 percent to 5 percent body fat (for men), and in this case the only improvements they can make to their climbing is by increasing their threshold and MS power. It is dangerous for a cyclist to try to lose weight if they already have a low body fat percentage.
Next we will divide climbs into two categories; short climbs and long climbs.