30.3
PDI
8.3 mi
DISTANCE
3,964 ft
GAINED
9.1 %
AVG. GRADE
FULL CLIMB STATS
INTRO
Mont du Chat rises above Lac du Bourget in Savoie, and the eastern approach from Le Bourget-du-Lac climbs 8.3 miles at a 9.1% average grade, gaining 3,964 feet to finish at 4,753 feet. It's one of two ways up the mountain - the other begins in Meyrieux-Trouet on the west side - and both converge near the summit.
The grade is the story here. After a short, gentler run out of town, the road tips up hard once it clears the roundabout at the edge of Le Bourget-du-Lac and barely lets go, holding near double digits for most of the remaining distance. It's a narrow road, closed in by trees for nearly the whole way up, with the view only opening onto the lake in the final kilometer.
The col has appeared in the Tour de France twice - a 1974 stage won by Eddy Merckx after he reeled in an attacking Raymond Poulidor on the descent, and a 2017 hors categorie summit finish topped by Warren Barguil. That 2017 stage is remembered most for Richie Porte's high-speed crash on the descent into Le Bourget-du-Lac - this same road - which ended his Tour with a broken collarbone and pelvis.
The road is seasonal - Savoie's department closes it each winter and reopens once conditions allow, typically around the first weekend of May (it reopened April 22 in 2026) - so check current status if riding in the shoulder season.
PLAN YOUR ROUTE
We've partnered with Sherpa-Map.com to bring you the best route planning tool. With a PRO Membership you can use this climb as a reference when creating your route. This climb averages 9.1% over its 8.3 miles, gaining 3,964 feet to a finish at 4,753 feet - one of the more consistently steep approaches in the Savoie region. The first kilometer or so out of Le Bourget-du-Lac is comparatively mild, but the grade tightens sharply once the road clears the roundabout at the edge of town.
The steepest kilometer begins around the 3.4 km mark and averages 11.1%, and the climb holds close to double digits for most of the distance from there to the tree-lined summit. There's little relief anywhere on the upper two-thirds of the route, so pace conservatively from the base.
Roadway: The D42 is paved the entire way and has been in good to excellent condition on our climbs and in recent rider reports, with a mix of older pavement and freshly resurfaced sections. It's a seasonal mountain road - Savoie's department closes it each winter and reopens it once conditions allow, typically around the first weekend of May; this year it reopened April 22, 2026 - so confirm it's open before a shoulder-season trip.
Traffic: Busiest through the first couple of kilometers out of Le Bourget-du-Lac and around the roundabout where local and tunnel traffic merge. Above the roundabout, traffic thins out considerably for a quieter final push to the summit.
Parking: Le Bourget-du-Lac is a lakeside town with several public lots near the start of the climb at the D42/D14 intersection - Map. It's a popular base for exploring Lac du Bourget, so expect more activity here in summer.
There are no services along the climb itself. The only stop is Restaurant des Aigles (Relais du Chat) at the summit, open daily April 4 through November 1 from 10am to 10pm, serving Savoyard fare with a panoramic view over the lake. Outside that window - or if it's simply closed when you pass, as it was on our own visit - there's nothing until you're back down in Le Bourget-du-Lac, so carry enough water and food to be self-supported for the full ride.
Before heading out on any cycling adventure check out our Things to Bring on a Cycling Trip and use our interactive check list to ensure you don't forget anything.
Le Bourget-du-Lac sits on France's largest natural lake, and it's worth building in time beyond the climb itself - the lakefront has swimming beaches, boat rentals, and views across to the Dent du Chat ridge you've just climbed. The spa town of Aix-les-Bains is a short drive around the north end of the lake, and boat trips run from the area to the lakeside Abbaye de Hautecombe.
Bring layers even in summer - the summit sits nearly 1,500 feet above the lake and can be noticeably cooler and windier than the start, particularly if cloud is sitting on the ridge. Check current conditions at both ends of the climb with our Weather tool before you head out.
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carlinguernsey
If you like 10% gradient, this is your climb! Enjoy the first couple of k, because once you leave Bourget du Lac the 10% starts and doesn’t let up until just before the top. The “good” news is that the gradient is pretty steady, so you can get into a decent rhythm. You get a great view at the top of the south end of the lake and Aix-les-Bains.
