Sunday it was 62F (17C) in Boulder, Colorado, and I went for a great endurance ride up to Jamestown, a cluster of 250 homes at 6,926 feet (2,105 m) elevation. Although the weather was warm there was still ice in James Creek. And, sure enough, Monday's weather was windy, wet and very cold (back down to freezing). Good trainer weather, in other words. This "shoulder season," as winter becomes spring, is perfect for trainer workouts on those days when the weather still won't let you ride outside.