I rarely ever see other bike commuters around here, particularly in winter. In summer months, there are 3-4 other regular bike commuters in my building, but I've been the only one since about October.

However, when I used to belong to the YMCA, there used to always be a huge influx of people working out in January -- which I always attributed to the "resolution effect" and people trying to work off their holiday poundage. By mid-February, things would usually get back to normal.