Termobomba Assos Primavera/Otoño P1

The Assos Spring/Fall ThermoBooster P1 is a thermal midlayer built to solve the problem every cool-weather ride creates: staying warm on the descent without overheating on the climb. Assos built it around Skuba, a circular-knit textile with a soft, carbon-brushed inner face that creates low-volume loft for insulation while still moving heat and moisture away from the skin during hard efforts. Assos rates the fabric 5/5 for breathability and 2/5 for raw insulation, which tells you where this thermal baselayer is aimed: active riding in variable temperatures rather than standing around in the cold. The AEPD 11 racingFit wraps the body in a second-skin, 360-degree compression fit, so it layers under a jersey or jacket without adding bulk at the shoulders or waist.

A handful of details push this beyond a basic base layer. The struzzoKragen collar uses a softer insulation panel to regulate your microclimate at the neck without needing to unzip or remove a layer mid-ride. Twin rear pockets mean you can wear the ThermoBooster P1 on its own as a thermal jersey on cooler days, not just as an underlayer. Raw-cut edges at the sleeves and waist eliminate seam ridges, so there's nothing to chafe under a tight-fitting shell. Assos also rates it 4/5 for packability, and it compresses down to roughly rain-jacket size, meaning you can stuff it in a jersey pocket once the temperature climbs mid-ride.

Assos designs the ThermoBooster P1 for three-season use: worn over a base layer or summer-weight jersey through spring and fall, or layered underneath stormproof outerwear as a midlayer during deep winter rides. It's available in the Blackseries colorway across a full size range from XXS through XLG and TIR. For riders who do most of their training in shoulder-season temperature swings, it's a layer built to stay on the bike rather than get shed and stuffed away by the second climb.