I always gear down for the winter for the reason of keeping warmer and avoiding muscle strains due to the cold.
Track training nights here start at 20:00 to 22:00, and in the winter (like now) it's pretty cold so spinning a high cadence is good for me, I still get home nice and sweaty even in this weather (it's cold, wet and windy in the UK at present...errr, for a change).