I've got a steel bike that I ride to work when it rains, which is nearly every day from mid-October to mid-June around here. I leave it outside and uncovered during the work day. Before I leave at night, I bounce it once or twice to knock the excess water off. Sometimes I do the same when I get home. I clean and oil the chain when it starts to squeal. Once in a while (maybe every two weeks) I use a bristle brush to knock the accumulated road grit off the frame.

The bike has survived two winters with this treatment and doesn't appear to be any the worse for it.