I'm fortunate to live in an area that allows cycling year round if you're okay with bundling up. However during the winter I just ride for the exercise and certainly not for performance.
It's interesting but it sounds like I try and get in riding shape doing just the opposite. It really hasn't been anything planned on my part but just how it's evolved the last several years. I try and build endurance first by riding LSD and then add intervals and intensity afterwards. Thus I can do longer rides earlier in the year at a comfortable pace but pick up the pace as the season progresses. The real key for me is getting rid of that darn winter weight. It becomes especially noticeable on the hills.
Whichever way we choose, it's good we're getting exercise and staying in shape.
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Ride your Ride!!