I voted for 41-55, because of the sheer convenience of rushing out of the house or office, jumping on the bike and just going.
Now that colder weather has come, I'm having second thoughts. Yesterday began with frost sparkling like diamonds everywhere and ended with the ride home beneath a huge moon. It's just a minute or so to manage gloves and overcoat and the rewards are immense.
I further realized that my best cycling memory of this year was riding home as our great February blizzard began, making first tracks as the world started to resemble a well-shaken snow globe and filled with the sense of peace that comes only with the prospect of being snowed in.
Paul