You can see my riding pattern in these charts:
http://www.flickr.com/photos/1430288...321906/detail/
Note that one chart will show mileage (in and out) ... in other words, the distances are recorded in miles and include both outdoor cycling and the riding I did on a stationary bicycle/spin bike/trainer.
The next chart will show the same time period, but it is in kilometers and shows only the outdoor rides.
Comparing the two will show where I switched to indoor cycling during the winter.
In general I took a week or two off here and there from November to January (while living in the northern hemisphere). During that time, however, quite often I switched to doing weights, walking, and/or participating in snowsports.
And Clifton ... I've spent three extensive periods of time off the bicycle either entirely or mostly because of injury or illness ... I can see where those times are on those charts. Yes, the fitness level diminishes, but it can come back. I'm starting to see that more and more recently.