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Siroko M4 Collection: long sleeve jerseys with thermal protection

If you practice cycling and you are looking for a versatile long sleeve jersey, the Siroko M4 collection for men and women is what you need. The M4 is a multi-seasonal line of clothing designed to keep you going through fall, winter and spring. Wear it with a thin base layer underneath in temperatures around 15 °C. Around 10°C, on top of a merino wool technical base layer. On a crisp spring morning, over a short sleeve jersey. If the rain or cold wind picks up, under a rain jacket or windproof vest. It can even be worn under a winter jacket when it gets really frosty.

The M4 long sleeve jersey offers a wide range of possibilities and it is perfect for any cyclist, from those who can only ride the bike on weekends to those who push themselves to the limits and demand top performance from their equipment. Therefore, having an M4 long sleeve jersey in your closet is an excellent investment. Let’s look at all its features in detail:


The M4 collection uses two fabrics from the prestigious Italian brand Carvico: Colorado and Dolomiti. The former combines polyamide with elastane, while the latter uses polyester and elastane. The latter is only used in fluorescent-colored styles. Both have UPF 50+ protection.

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These fabrics are very soft, lightweight and elastic, providing a very pleasant feel on the skin and allowing the jersey to fit perfectly to the body without compromising flexibility or ease of movement.

Thermal protection is provided by the brushed skin side that keeps warm air between the jersey and the skin. Thanks to their breathability, the fabrics wick away the moisture from sweat, expel it to the outside and keep the body at the ideal temperature no matter the weather. This way we don’t freeze from sweating even at peak effort.

Cut and Fit

As we have already mentioned in other reviews of Siroko products, women’s M4 jerseys feature a different design than men’s jerseys in order to perfectly fit the female body. This does not mean that a woman or a man cannot wear a men’s or women’s jersey. The fabric of the M4 is very flexible and adapts easily to any body type.

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What every cyclist, male and female, should keep in mind is that the fit is very snug and feels like a second skin. Therefore, it is key to take your body measurements and check the size guide as the right size means you can get the most out of the thermal and aerodynamic properties of the jersey. To determine your size, take a look at our guide on how to find the perfect size for your cycling clothing.

As usual in our designs, the back panel is slightly longer than the front panel, featuring a drop tail. This way, when we are leaning forward on the bike, there is no shortage of fabric at the back and no excess at the front. As such, the jersey fits snugly, does not create wind resistance and protects the lumbar area.

Collar and Waist

The collar is round, medium-sized and made of the same stretch fabric as the rest of the jersey to fit the neck perfectly and keep out the cold air.

The elastic band with an inner silicone grip at the bottom hem is a must. This key element guarantees that the jersey fits well, does not move up or let the wind in when we’re cycling.


Unlike the M2 long sleeve jerseys, the M4 jerseys do not have raglan sleeves. Instead, they feature straight sleeves that begin where the shoulders end and have flat, inner seams.

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The sleeves are long enough so that when we get on the bike and stretch our arms, our wrists are not exposed to the cold. Besides, the sleeves are finished with an elastic cuff that can be placed over a cycling glove if necessary.


We didn’t invent gunpowder here. The M4 jerseys feature the classic three rear pockets, plus a lateral opening with an SBS semi-automatic zipper on the right side for easy access.

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The entire pocket area has an elastic reflective binding to prevent objects inside the pocket from slipping out and to hold in place any items that stick out (vest, gloves, pump, etc.).

The central pocket has a larger capacity than the side pockets. All three are easily accessible even while wearing gloves thanks to the elastic binding. Their stretchy fabric allows the pockets to adapt when loaded with items and return to their original shape when emptied.


The front zipper also features an SBS semi-automatic lock. This means that it does not slide freely unless the pull tab is lifted to a certain point. It allows you to open the zipper as far as you want, and when you lower the pull tab, the zipper stays in place. Perfect for when we face a climb and want a little more ventilation. The entire zipper is protected on the inside with fabric to prevent it from jamming and also to avoid chafing on the neck and torso, hair snagging, skin damage or irritation as well as to protect the bib tights.

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One more detail worth mentioning here is the zipper hut at the top end so that the pull tab is safely stored in a “zipper garage” when we close it completely. This simple piece of folded fabric helps avoid neck discomfort.

Reflective detailing

In fall and winter there are not that many hours of daylight to go out cycling, so reflective detailing is of utmost importance. In the M4 jerseys you can see it on the hems of the pockets and on the Siroko logo on the back of the left shoulder.

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So much for all the features of Siroko’s M4 jerseys collection. These long sleeve cycling jerseys for men and women are extremely versatile and have excellent thermoregulating properties. Keeping you warm in different conditions while being breathable enough to quickly wick away sweat on a tough climb is not an easy thing to achieve. Our M4 jerseys do just that, and that’s why it’s well worth including them in your cycling wardrobe.

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