Summer baselayers serve a different purpose than their winter counterparts. When temperatures climb, the goal isn't thermal retention—it's managing the moisture your body produces under load so it can evaporate efficiently rather than pooling against your skin. The Assos Summer NS Skin Layer P1 uses their Type.431 fabric specifically for this task, a lightweight mesh construction that prioritizes airflow and moisture transport over any insulating properties.
The sleeveless design reflects how heat builds during warm-weather efforts. Your torso generates significant moisture, but your arms benefit from direct airflow and don't need the additional layer. By eliminating sleeves entirely, Assos keeps the baselayer focused on your core—the area where moisture management matters most and where a jersey alone can leave sweat sitting against skin. The result is a piece that weighs almost nothing and adds no perceptible bulk under your kit.
Type.431 fabric uses an open mesh structure that creates channels for air movement between your skin and your outer layer. This isn't about wicking in the traditional sense—it's about creating space for evaporation to happen. The mesh holds the jersey fabric slightly away from your skin, which allows moisture to spread across a larger surface area and evaporate faster than it would if your jersey were pressed directly against you.... Read More
Fit follows Assos's regularFit pattern, which provides enough compression to keep the fabric in contact with your skin without the aggressive squeeze of their racingFit pieces. This matters for a baselayer because the fabric needs consistent skin contact to do its job. If the baselayer bags or bunches, moisture can pool in those gaps rather than spreading across the mesh where it can evaporate. The regularFit strikes a balance between staying put during movement and remaining comfortable across long efforts.
The construction keeps seams minimal and flat where they do exist. On a layer that sits directly against skin, raised seams create friction points that become noticeable over hours in the saddle. Assos positions what seams remain away from high-movement areas and keeps them low-profile enough that you won't notice them under a jersey.
Where this baselayer fits in your summer kit depends on conditions and personal preference. Some riders skip baselayers entirely when temperatures climb, but the mesh construction here adds so little thermal load that the moisture management benefits often outweigh the marginal weight. On days where you're generating significant sweat, having that separation layer between skin and jersey can keep you more comfortable than going without—particularly on longer efforts where moisture accumulation compounds over time.
