When looking at timetables be aware that they're in French so: L = Lundi / Monday, M = Mardi / Tuesday, Me = Mercredi / Wednesday, J = Jeudi / Thursday, V = Vendredi / Friday, S = Samedi/ Saturday & D = Dimanche / Sunday.
In-resort bus services run until late at night and are free with your lift pass. There is a handy but slow bucket lift (with a piste beneath it) running through the resort from the Tourist Office to the main DMC lift at the top. Known locally as the 'lobster pot', it doesn't run in the evenings.
Remember to flag the bus. Bikes can be taken aboard these buses, no extra charge, however, it's subject to availability as the number of bikes they can carry is limited.
Bus services will take you from Lyon and Geneva airport to Grenoble Gare Routiere, the city's train and coach station. These routes work during the summer and winter seasons. From Grenoble, take another bus to Alpe d'Huez - see below.
Buses bring you to Alpe d'Huez from Grenoble Gare Routiere. The most direct service is the Transaltitude direct bus. It's strongly advised that you book this online in advance as it can get busy during the winter. Online pricing and bookings are typically available from mid-November. You should arrive at the bus at least 15 minutes before boarding with your tickets (printed out on paper or in electronic format on your smartphone).
Alpe d'Huez is connected to neighbouring ski resorts and towns via bus services. For Les Deux Alpes, take line 3020 to Bourg d'Oisans and then line 3030. There is also a daily bus from Grenoble to Bourg d'Oisans (L3000), from where you can pick up either of the connecting buses to Alpe d'Huez or Les Deux Alpes. There's no need book these buses in advance, just pay the driver on arrival.
During the winter season, there is a direct shuttle bus to Les Deux Alpes on Wednesdays and Thursdays. It leaves at 08:45 and returns at around 17:30-18:00. The service costs about 12€ return and tickets can be booked from the Palais des Sports in Alpe d'Huez (70 Avenue des Brandes - the desk is in the foyer immediately on the left-hand side as you walk in) or the VFD bus stations in Les Deux Alpes (112 Avenue Muzelle).
Note that these timetables may vary throughout the year and during holidays so please contact the bus companies in advance to avoid disappointment.