Castelli Fly LS Jersey Review

The Castelli Fly LS Jersey is a lightweight, long-sleeved thermal jersey, ideal for the mid-season in early autumn, spring, or even winter in some temperate regions. With a close-fitting cut, it’s designed for intense rides while remaining relatively warm. We were able to put it to the test throughout October.

By Guillaume Judas – Photos: ©Vncent Lyky

Unlike modern, very fitted summer clothing with materials that promote aerodynamics, the outfits generally offered for winter or mid-season are a little looser, generate more folds or flapping, and, in doing so, are less effective against the wind. All athletic cyclists can see it: we ride slower in winter, and generally as soon as we put on long clothing again, and this is not just a matter of physical condition, but rather of air resistance. Moreover, all wind tunnel studies can confirm it: clothing is at least as important as equipment in terms of aerodynamic performance.

Based on this observation, Castelli has designed a long jersey dedicated to those who want to continue riding fast even when temperatures drop, which provides the same sensation of speed as an aero jersey, while offering more warmth. The cut of the Fly LS (Fly as in flying, and LS as in Long Sleeves) is inspired by aerodynamic summer jerseys, with a close-fitting cut, a low collar, light weight, a stretchy fabric that provides warmth and good freedom of movement. As the jersey is intended for days with less light, it has reflective strips on the back for better visibility.

But it is above all a jersey intended for training rides. It therefore offers three fairly deep pockets at the back to slip in a large smartphone, some food or a repair kit, and especially a windproof vest to add a layer of protection just in case.

On the road with the Castelli Fly LS jersey

Available in three colors (anthracite, blue, and fluorescent yellow) and seven sizes (XS to 3XL), the Fly LS is very fitted on the torso, respecting Castelli’s usual sizing. Just like a Climber’s or Free Aero summer jersey, in fact. This cut requires wearing a very fitted base layer as well, to facilitate the layering between the two garments. With a tight short-sleeved or sleeveless base layer, everything goes very well, but the use of the jersey is limited to temperatures of around 15°C. For cooler conditions (down to 11-12°C), it is preferable to choose a long-sleeved base layer, which must necessarily be very tight, otherwise it will cause discomfort with the already very fitted sleeves of the Fly LS.

During the first few hundred meters of each ride, the collar cut is surprising and causes an unexpected feeling of coolness for a long-sleeved jersey. But you get used to it very quickly, especially if the session is intended to be intense, maintaining good pressure on the pedals throughout the ride. In an aerodynamic position on the bike, the jersey is very comfortable. Its fitted cut does not restrict movement. You don’t feel overheated, at least if you stay within the temperature range of use specified by the brand (12 to 18°C).

For lower temperatures, or for those of us who are more sensitive to cold, it is possible to add a well-fitted windproof vest, which has the advantage of providing additional protection at the collar, but without causing additional flapping at the sleeves. This type of vest can also protect against a light shower. However, the Fly LS jersey is not designed to truly withstand cold rain that can sometimes surprise in autumn or early spring. Fortunately, the deep and practical pockets allow you to carry this famous vest, or even a packable waterproof jacket.

We also note the impeccable finish of the jersey, including an easy-to-handle zipper, and an overall impression of quality found on all Castelli garments. Ultimately, the Castelli Fly LS jersey stands out as a high-end, comfortable thermal jersey, ideal for athletic rides in moderate temperatures. It is not a jersey that protects against humidity, nor is it for those who plan to admire the scenery in winter conditions. It also requires wearing a very fitted base layer. But in our opinion, it is an essential item in the wardrobe of the committed rider, for autumn rides, or even more certainly those in early spring when training is most intensive with the triple need to be comfortable, performant, and protected from the cold.

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