I could often notice during training camps or stage races, even with well-known professional cyclists, that the athletes were not taking enough carbohydrates (CHO) to regenerate the glycogen stores utilized in previous efforts. 

Sherman et al. (Am.J.Clin.Nutr. 1993; 57 : 27-31) demonstrated that it takes 10g of CHO per kg of body weight in order to keep a constant level of muscular glycogen in a group of cyclists and runners training intensely for 1 hour every day for 1 week at 75% of their VO2max, with 5 final sprints of 1’ at 100% of VO2max. 

While one hour of total high intensity efforts is quite frequent in cyclists training, in race events it is usually even more than that, especially in mountain stages. Efforts around the anaerobic threshold values and above are the ones that “eat into” glycogen stores most of all, but also a good Medio pace can require high amounts of CHO. 
One hour of effort at Soglia intensity can cost up to 1200 Kcal, almost exclusively obtained from CHO, corresponding to about 300g of muscular glycogen. 
One hour at Medio pace can cost about 800 Kcal, 60-70% of which is CHO, corresponding to 120-150g of glycogen. 

10g of CHO/kg of body weight is a remarkable amount of carbs: for an athlete of 70kg it corresponds to 700g, which is an amount quite hard to reach with a traditional nutrition strategy, even if rich in pasta, rice, potatoes, cereals, etc. 
It is then necessary to supplement with liquid carbs (maltodextrines, glucose solutions) for at least about 150g. 
I remind that for pasta, rice and cereals, 75-80% of the weight is CHO, for potatoes it is 20-25%, for fresh fruit and vegetables is about 10%. 

Therefore during stage races or in the 24-48 hours prior to a “classic event”, but also before a very demanding training session or simply to recover after an important effort, it is imperative to pay attention to the amount of CHO we should take, maybe with the help of a little food scale. 

I still remember the famous “midnight spaghetti” of marathon Olympic champion Gelindo Bordin, who was able in such way to saturate his glycogen stores in the last hours before the race…