With 310 days of sunshine each year and summer temperatures seldom over 80 degrees, Leadville is a destination for history, mining and outdoor buffs. Snow remains on the ground from end of October until middle of May with average annual snowfall of 200+ inches.
Days may be warm but nights are cool to cold. Bring layers of clothes. Rent a 4-wheel drive for the winter or when snow is forecast. Use sunscreen--skin burns easily at altitude even when skies are cloudy.
We heard a number of reports about bears on the mountain bike trails. I don't think these ones were friendly like Yogi. Seek local advice before going off the beaten track.