Looking good in an ioMerino baselayer

Baselayers

Shop cycling base layers built to wick sweat and regulate temperature under any jersey. Choose summer mesh for breathability or winter merino for warmth.
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Jerseys to wear over them

View all Short Sleeved Jerseys

Cycling base layers: the most work per gram

A base layer sits against your skin and moves sweat away from it. That sounds minor and it changes more than any other single garment, because sweat sitting on skin is what makes you cold on a descent and what makes you clammy on a climb. Move it outward and the air trapped in your jersey stays dry and warm.

They work in summer too

This is the part most riders resist. A lightweight mesh base layer under a summer jersey makes you cooler, and the mechanism is straightforward. The mesh lifts the jersey a millimetre off your skin so air can move underneath, and it spreads sweat across a wider area so more of it evaporates. Evaporation is your cooling system, and a jersey plastered flat against wet skin shuts it down. On a 30 degree Adelaide day a mesh layer is worth more than a lighter jersey.

Merino and synthetic

Merino holds warmth even when damp, resists odour over consecutive days and feels comfortable across a wide temperature band. It is the winter choice and the bikepacking choice.

Synthetic knits move moisture faster and dry faster, which suits high intensity and heat. Modern blends put merino against the skin and synthetic where the wear happens, and those are usually the best of both.

Sleeve length by temperature

Sleeveless mesh for 25 degrees and up. Short sleeve for 15 to 25. Long sleeve merino below 15, under a jersey or a jacket. Below 5 degrees a heavier long sleeve merino layer does more for warmth than a thicker outer garment does.

Fit is not optional here

A base layer has to be snug. Loose fabric cannot wick, because wicking depends on contact with your skin. If it drapes, it is doing nothing. Size to your normal fitted size and expect it to feel tighter than a jersey.

Care

Wash merino cool and skip the fabric softener, which coats the fibres and destroys both the wicking and the odour resistance. Dry flat where you can.

We stock base layers from Castelli, Santini, MAAP, Pearl Izumi and Isadore. Pair them with bib shorts and a short sleeve jersey, or see the full winter cycling range.

Base layer questions

Do I need a base layer in summer?

A lightweight mesh base layer makes you cooler, which surprises most riders. The mesh lifts your jersey a millimetre off your skin so air can move underneath, and it spreads sweat across a wider area so more of it evaporates. Evaporation is your cooling system, and a wet jersey plastered flat against your skin shuts it down.

Merino or synthetic base layer?

Merino holds warmth when damp and resists odour over consecutive days, which makes it the winter and bikepacking choice. Synthetic knits move and release moisture faster, which suits heat and high intensity. Blends that put merino against the skin and synthetic where the wear happens give you most of both.

How tight should a base layer be?

Snug. Wicking depends on the fabric touching your skin, so a base layer that drapes is doing nothing at all. Size to your normal fitted size and expect it to feel tighter than a jersey.

What size should I order?

Italian brands including Castelli and Santini run smaller than Australian sizing, typically by one size. Pearl Izumi and MAAP run closer to true. Each product page links the brand's own size chart. If you are between sizes and want a race fit, size down. For a layered fit, size up. Our Adelaide showroom carries most of our range if you want to try before you buy.

How long does delivery take?

Orders start processing within one working day of your payment clearing. Australian orders of $100 or more ship free, and worldwide orders of $190 or more ship free. Express Post within Australia is $19.95, and orders placed before 4pm ACST go out the same day and typically arrive in 1 to 3 days. Helmets and shoes carry a shipping surcharge and are excluded from free shipping.

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