There are vast numbers of baselayers available from bike and outdoor clothing brands, but this Craft one has stayed in the ‘either wearing it or washing it’ laundry loop since we got it. It’s really long in the body and sleeves, so you can tuck it into gloves and trousers/shorts to prevent any riding up. The stretchy fabric gives maximum skin contact for warmth without obvious bunching. It spreads sweat fast and wide to flatter the performance of ‘breathable’ layers on top, and dries quickly. Despite its soft feel, it’s survived washing and wearing well too. You could probably find something similar for a fiver less, though.
Price $51