Mont Blanc does not so much loom over Chamonix as lean on it. The valley is a deep, narrow trench of the Arve river with the highest peak in the Alps, just under 4,810 metres, standing right at the top of it, and the glaciers come down so close that you can see the cracks in the ice from the main street. Modern mountaineering has a birthday here. In 1786 two local men, Jacques Balmat and Michel Paccard, reached the summit for the first time, and the town has been selling the idea of going up high ever since. In 1924 it also hosted the first Winter Olympics.
You do not need to be a climber to feel the scale. The cable car from the valley to the Aiguille du Midi rises to about 3,840 metres in a single, rather pale-faced journey, and the rack railway to the Montenvers drops you at the edge of the Mer de Glace, the longest glacier in France, which has visibly shrunk over the last few decades. Down in the centre, the statue of Balmat pointing at the summit stands in the middle of the square, and the cafés are full of people in boots and sunburn.
The roads are a mixed blessing. North, the Col des Montets climbs gently through Argentière and Vallorcine to the Swiss border, and onward over the Col de la Forclaz to the Rhône valley, a pleasant and well-surfaced ride. South, the road runs down the valley through Les Houches toward Sallanches. In summer, traffic is heavy, and lorries bound for the Mont Blanc tunnel, which opened in 1965 and runs 11.6 kilometres to Italy, fill the valley road. After the 1999 fire in the tunnel, safety rules were tightened. Go early, since the light is gentle and the air is cold.
Chamonix has plenty of fuel, bike-friendly cafés and rental shops. Expect high prices, especially in July and August, and avoid parking on streets marked for residents or pedestrians. Afternoon thunderstorms in the mountains can arrive quickly, so keep an eye on the clouds. On a clear evening, sit by the river as the last light climbs the Aiguilles and turns the granite pink.