If you’re watching the ‘Tour de France’, you’ll probably hear the commentators at one time or another talk about the hill CLASSES or RANKING of each climb. They are number 1 through 4. Although I did understand that 1 was the hardest and 4 the easiest, I could never quite figure out how they come up with these ratings.
A quick Google search gave me this answer from a user name “Blip” on CyclingForums.com
“There are loosely 4 Categories of climb. They are classified from ages ago as to the capacity for a Citroen 2CV to climb the hill and if so in which gear. I know this sounds like madness but it is 100% true. A category 3 climb it could climb in 3rd gear ( a small rise ) category 2 2nd gear, cat 1 First gear and Hors Categorie or H.C is where the little old 2CV could not climb it no matter what!
You make think I am making this up but it is true and has stuck to this day. Any new climbs are rated against existing category climbs. It does have an element of slope and gradient etc but has been simplified in a fantastic, old school method.”
So there you have it. And I stand corrected: There are FIVE hill classes, not four.
You have to laugh at the method they came up with!!