Base Layers

What does a base layer actually do?

A base layer sits next to the skin and moves sweat away from it, so the jersey over the top has something dry to work with. That is what keeps you comfortable on an early morning ride and stops the chill setting in when you slow down or the wind picks up. It works as a system with the rest of your road cycling clothing rather than in isolation.

Merino or synthetic?

Merino wool holds warmth when damp and resists odour over several rides, which suits long days and cooler months. Synthetic meshes in polyester or polypropylene dry faster and weigh less, which suits hard efforts and summer heat. Plenty of base layers blend the two to get some of both.

Which weight for which season?

Lightweight summer options are close to a mesh vest and are there for sweat management rather than warmth, so they still make sense in July under a thin jersey. Thermal layers for winter are brushed on the inside and are designed to be worn under a jacket, where the extra loft does the insulating.

Sleeveless, short sleeve or long sleeve?

Sleeveless keeps the core covered without adding anything at the arms, which pairs well with summer kit. Short sleeve gives a little shoulder and upper arm cover for spring and autumn. Long sleeve is the winter choice and sits under a jacket without bunching at the cuff if the fit is right.

What should I check buying used?

Fit is the thing that matters most, because a base layer only works if it is in contact with the skin, so check the size and ask about the cut before buying. Look at the state of the fabric at the shoulders and underarms where wear shows first, and on merino check for thinning or small holes. Ask whether it has been washed with fabric softener, which clogs the wicking on synthetics.