I like to wear a base layer in all seasons rides. Was not thrilled with what I saw on line and most bike shops don’t carry these items. When I saw Endurance Threads shirts I was intrigued with the style and fabric, so ordered one in a large, since I usually take a medium or large (165 lbs/5-9) Came 2 days later and immediately tried it on to find it was almost impossible to pull over, way too small. Folks at Endurance said it was designed to be tight to wick better, but truly did not fit. I returned it and quickly received an x-large which was still tight but wearable. Have ridden with it a few times and very happy with the temperature control in both warm and now cooler weather. Well made product. Pay attention to the size chart.