We plan to spend 4 days in Normandy next spring without a car. Is it possible to use a combination of bicycling and train trips to see the sights in the area? Are there bike paths or good routes with very little traffic? Would Bayeux be the best town to base out of? Any towns that would be particularly pleasant to visit via bicycle? Thank you!
If you get a Michelin 1:200,000 scale map, then virtually any white colored road will have very little traffic on it.
No bike paths that I've noticed. The back roads will have farm equipment in the spring that's moving at exactly the wrong speed to get around. Hog you lane so that an over-taking and an on-coming car won't both be beside you at the same time. Shoulders are non-existent or so rutted that you'll bust your tail if you leave the pavement.
I've biked around Burgundy (but not Normandy) and helped a friend (a little) to plan an upcoming trip to Normandy. Based on that (which is a little second hand) and my own trip to Normandy (with a car), I'll hazard a few observations. First, bicycling is a wonderful way to see parts of France. There are plenty of bike routes (not paths) there, and plenty of companies that offer guided tours, so i think the biking there is probably top notch. Normandy is wetter than most other parts of France, so you mus plan for the possibility of rain. Unless it's a real storm that probably just means rain gear. Fall is the driest time of year. If you are thinking to stay in one place, doing day trips, Bayeux is not a bad choice. It's on the rail line from Paris and connects to local trains NE as far as Deauville and SW to Mont St. Michel; there is another line that goes north into the Cotentin Peninsula. So you have options, including both loops and longer trips with return by train. The trains are slow. And Bayeux is charming and interesting. However, the best base for you will depend on your whole itinerary and your overall priorities. Settle those first and then pick a base.
Oh, and I strongly recommend the IGN topographical map series, 1:100 000, for planning and navigation. These are true topo maps and the scale is just right for cycling in the same way that the Michelin series is just right for motorists. Depending on your plans, you probably only need one map.