Cycling shorts for the winter: Castelli Polare Bibtight with Polartec AirCore technology
TOUR
· 30.10.2025
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New material combination protects against the cold
The Italian brand Castelli presents the Polar Bibtight presents a pair of winter trousers designed for cycling in extreme sub-zero temperatures. The model combines two different materials: Polartec AirCore on the wind-exposed front and Thermoflex fleece on the less wind-prone areas. This zoning is intended to ensure optimum protection and breathability at the same time.
The development was aimed at transforming riding in temperatures between -5°C and 5°C from a fight for survival into a pleasant training experience. Castelli exclusively uses Polartec AirCore technology, which combines wind-repellent and water-repellent properties with high stretch and breathability.
Windproof at the front, vapour-permeable at the back
The Polar Bibtight relies on a well thought-out material distribution according to the wind load of different body zones. The entire front panel of both gender versions is made of Polartec AirCore material, while the seat area and the back of the legs are equipped with Thermoflex fleece. This distribution takes into account the fact that the front of the body is exposed to the wind when cycling, while the back area requires less wind protection.
The Thermoflex material in the less exposed areas offers maximum breathability and stretch without unnecessary wind protection. This zoning prevents overheating in areas where wind protection would be counterproductive. The combination of both materials is designed to create the optimum balance between thermal insulation and moisture management.
KISS Air2 upholstery with customised upholstery zones
The integrated KISS Air2 seat pad utilises an anatomically shaped construction with variable foam densities. The maximum padding thickness is in the ischial tuberosity area, reducing to medium thickness under the perineum and reaching minimum thickness at the edges. This gradation follows the different pressure loads when cycling.
The top of the pad uses an ultra-soft fabric that is designed to reduce chafing and abrasion. The two-layer foam adapts to the anatomical features and is designed to prevent pressure points. Brand Manager Steve Smith explains: "We've created the perfect blend of warmth, stretch and breathability to make very cold rides as comfortable as possible."
Visibility thanks to reflective material
For better visibility in the often poor light conditions in winter, Castelli has integrated reflective strips above the front knees and on the rear calves. This positioning is intended to improve visibility for other road users without restricting freedom of movement. Ankle zips make it easier to put on and take off in cold conditions.
The Polartec AirCore technology completely dispenses with PFAS-based chemicals and uses recycled polyester yarns. The material creates an extremely dense membrane that keeps out the elements but still allows air to pass through. During development, Castelli and Polartec prioritised breathability over water repellency, as soaking from the inside through sweat is just as problematic as moisture from the outside.
Availability and prices
The Polare Bibtight is available in two gender-specific versions: Polare 2 for women and Polare 4 for men. Both models are only available in black and cost 219.95 euros each >> available here. The trousers are aimed at ambitious winter cyclists who also want to train in extreme temperatures.
The AirCore technology was developed with the aim of achieving both wind-repellent and water-repellent properties without compromising breathability. The material allows minimal air to pass through, which ensures ventilation without causing any noticeable loss of cold. This balance is intended to reduce sweating and at the same time protect against cooling.
