The average is meaningless because the climb is highly irregular. It’s known to be the easier side, but still the total length is 22 kilometers with an average gradient of 5.5%. In the middle you got a surprise deep descent, and this is exactly why the average gradient from this side is meaningless. You will be losing most of the height that you have gained with a sharp steep switchback descent. The relief is short, as you will now start climbing the steepest part right up to the largest dam in Europe, La Grande Maison. Once at the top of the dam you can see the road climb up through the valley to the Col du Glandon. Riding this side you need to be prepared for long sections at 8% – 10% and some shorter, steeper sections of up to 13%.
You will be losing most of the height that you have gained with a sharp steep switchback descent
When you do the climb via La Chambre you will have a killer last two kilometers exceeding 10% with stretches at 12%. The climb starts behind a town called St Etienne de Cuines. The start of another great climb, Col de la Madeleine, is only a few kilometres to the north of here.
This side is considerably steeper. At some point you will be crossing the small ski village St Columban des Villards, a good place to take a break, as some real hard work is still to come. Leaving the village, you will be faced with a gradient around the 9%, which will ease off again after 5 kilometers. Get yourself ready as the last switchbacks are seriously tough exceeding 10%. If you like, after a little dip you can easily climb to the nearby Col de La Croix de Fer.