Specialized Prime-Series Alpha jacket review

Specialized’s Prime-Series Alpha jacket uses Polartec's Alpha Direct insulation for this winter warming mid-layer

Specialized Prime-Series Alpha Jacket
(Image: © Ruby Boyce)

Cyclingnews Verdict

Using Polartec’s Alpha Direct material for insulation, Specialized has created an excellent mid-layer jacket for cold weather protection


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    Comfortable semi-road fit

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    Extremely warm

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    Very lightweight

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    Two-way zip


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    No rear pockets

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Specialized’s Prime-Series is a winter collection featuring this Alpha jacket, a thermal insulated long sleeve jersey and accessories like waterproof and thermal winter gloves that all use Polartec materials for insulation. 

The Specialized Prime-Series Alpha jacket arrived through my door just before starting the Rapha Festive 500 and the terrible conditions this year couldn’t have been a more apt testing environment for this Polartec insulated mid-layer jacket.

Design and aesthetic

Polartec’s Alpha Direct insulation is used in the Alpha jacket which gives the inside of the jacket a lofting quality to trap and regulate heat next to the body. The fibres which are attached to a mesh lining are also hydrophobic to resist moisture and help the jacket dry quickly. Evolved from the original Alpha material, Polartec’s new Alpha Direct insulation does not require any backing material which helps further improve breathability and moisture management while being soft when worn against the skin. Specialized has used Alpha Direct across the chest, back and arms with an insulation gap under the arms and down the flanks to stop too much heat build-up. The sleeve cuffs also have a band without insulation to presumably aid a gapless connection with gloves.

The Prime-Series Alpha jacket has a semi-road fit and has a decent amount of stretch to avoid binding our unwanted tightness and the simple collar is a good balance between out the way yet protective from the cold. A two-way zipper means you can easily unzip layers from the bottom to avoid turning into a parachute and they are cam-locked to save you the hassle of hunting for zip tabs with thick gloves while climbing. A zip garage stops irritation to the neck and the zip is backed to stop drafts. There is a gripper along the lower hem to hold it in place and a single internal pocket for storage.


Specialized has really nailed the cut of the Prime-Series Alpha jacket and with the perfect balance of close enough to be worn under a hardshell yet still plenty of room for layering underneath. This makes the jacket extremely versatile whether as a mid-layer or worn as an outer layer. If you do wear it as an outer layer it will be best suited to dry days as the jacket does not offer any water resistance. 

Where the Prime-Series jacket shines is being used as part of a layering system. The warmth offered by the Polartec Alpha Direct insulation is quickly noticeable and when paired with a hardshell, the lofting quality of the fibres creates a warm barrier between yourself and the unpleasant winter that is going on around you. I wore it under a Rapha Classic Winter jacket for rides that barely made it above freezing and never felt uncomfortable despite some very cold conditions. The light and thin construction sits very comfortably under a jacket as well to the point it's almost unnoticeable.

Any excess heat or moisture is dealt with extremely efficiently and on lengthy climbs which saw other riders' jackets flapping all it took was a partial unzipping to quickly flush out unneeded warmth before battening down the hatches and avoiding any chills taking hold. While I haven’t been soaked while wearing it, any instances of moisture have dried extremely quickly which is key to staying warm in winter conditions.

The lack of pockets may detract some but as a mid-layer, it isn't vital and removing unessential fabric and pocket structure benefits the performance of the garment. The inside pocket is handy to slip a phone and other slim items into when you are walking around a cafe with your jacket off although not ideal for riding as it extends to the bottom hem and can touch your legs as you pedal.


Keeping the core warm is absolutely essential when riding in winter and Specialized’s Prime-Series Alpha jacket is perfect for significantly bolstering winter layering options. The jacket's thin construction slips very comfortably under an outer layer and despite its minimal bulk, the Polartec Alpha Direct adds a significant amount of warmth without succumbing to unpleasant moisture buildup. It’s expensive but if you are committed to cold weather riding this will be an excellent addition to your winter wardrobe.

Tech Specs: Specialized Prime-Series Alpha Jacket 

  • Price: $225.00 / £N/A / €N/A
  • Weight: 230g
  • Sizes: XS, S, M, L, XL, XXL
  • Colours: Black, Taupe
  • Protection: Polartec Alpha Direct Insulation

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Graham has been part of the Cyclingnews team since January 2020. He has mountain biking at his core and can mostly be found bikepacking around Scotland or exploring the steep trails around the Tweed Valley. Not afraid of a challenge, Graham has gained a reputation for riding fixed gear bikes both too far and often in inappropriate places.