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Photo Credit: Fiona Outdoors

Rab Alpha Flux jacket


Last updated: 23-Jan-19

By Fiona Outdoors

A lightweight insulated jacket is a great item of kit for ultra runners. It can be used during a run for an extra layer of warmth, especially when it’s cold or windy, or stored in a rucksack for such times when you might need it, perhaps when stopping for a refuel or at a race checkpoint.

Rab state that the Alpha Flux jacket is: “Lightly insulated and highly breathable, with stretch fleece, for temperature regulation and freedom of movement during 'on the move' multi-season use.”

I have been testing the Rab Alpha Flux women’s jacket in a size UK10 in a variety of locations and different conditions.


  • Lightweight yet durable, abrasion-resistant nylon outer fabric
  • Polartec Alpha Direct 90 insulation
  • Stretch fleece side panels, cuffs and thumb loops
  • Polygiene STAY FRESH odour control treatment
  • YKK front zip
  • Internal storm flap
  • Chin guard
  • Fitted hood
  • Thumb loops
  • 2 YKK zipped hand pockets
  • Male and female “slim” fit
  • Weight: women: 265g/men: 315g
  • £140
  • Rab online

Pros: What’s good about Rab Alpha Flux jacket

The fit is brilliant. The UK10 fits neatly over a lightweight baselayer. The length is great for running and the thumb loop cuffs work well, even with my long arms.


Photo credit: Rab Equipment

Perhaps looks should not be that important, but I think the jacket is a flattering design. I was sent a black jacket to try and this would not be my first choice as I prefer brighter colours but the coloured zip makes the jacket look more attractive.

The different use of insulation and fabrics creates a lightweight jacket with warmth in the right places. The Polartec Alpha Direct 90 insulation is located in the front, back, upper arms, shoulders and at the side of the hood. These are the places where you will be most affected by wind chill and therefore need more warmth.


I like that the fleece style insulation is on the inside and a nylon fabric is on the outside because fleece tends to wear and look bobbly so if it’s kept on the inside the look of the jacket on the outside remains good.

The jacket is warm but also breathable. I have used it for high-energy activities and while I have sweated, I have stayed warm and dry.


Polartec Alpha is a great product in my experience. It maintains temperature even when I am working hard and sweating. I find the Polartec Alpha offers good breathability and it dries quickly. I have tested a number of products with this type of synthetic insulation and all have performed well.

A stretchy fabric is inserted on the sides, lower arms and hood, where you need more freedom of movement when doing activities such as running, walking and climbing.

Another good point about this jacket is that is can be used for a variety of sports. I have found it most useful for fast-hiking, winter trail running, mountain biking and skiing. It’s perfect for wearing to the pub as well because it looks smart.

  • The hood fits well, so you could wear it while running without fear of it falling down.
  • The front zipped pockets have a nice soft feel inside and they are useful as hand warmers mid run.
  • The zip guard at the chin is a nice touch.
  • The jacket can be stuffed into a rucksack when you do not need it and then used when you stop or after a run.
  • The Polygiene STAY FRESH odour control treatment does seem to work. I wore the jacket repeatedly – for testing purposes! – and it didn’t whiff too badly!


Cons: What’s not so good about Rab Alpha Flux jacket

I would prefer the jacket to be a little lighter in weight. It feels a bit heavier than others in this kind of style and if weight is important, such as what you put in your race pack, then you might reject the jacket for that reason alone.

I am not sure there needs to be insulation at the back of the jacket. Other styles have the stretch fabric at the back and keep the insulation to the front only. However, this would sacrifice on warmth.

An inner zipped pocket would be useful. Carrying anything in zipped hand pockets lower down the jacket can be annoying when running, cycling, walking or skiing because the items bang against your torso/upper thighs.

I would also like to see a two-way front zip for convenience.

I think that £140 for a lightweight insulted jacket is quite high, although Rab products do wear well.


If you’re looking for a warm but fairly lightweight jacket for running or to use when you need to stop mid-run or post-run, the Rab Alpha Flux is worth considering. The Polartec Alpha insulation is excellent and the combination of stretch fabric makes it a jacket that is easy to wear and is great for chilly conditions.

You might wince at the price but Rab products are long-lasting in my experience.

Design 9/10
Features 8/10
Performance 10/10
Value 8/10
Overall 9/10

Others to try

Berghaus Gemini Hybrid insulated jacket
Berghaus Teallach X insulated jacket
Yeti Clive Hybrid down hoodie
Mama Rime Hybrid Flex jacket

About the writer: Fiona is a keen runner, preferring off-road and hilly to flat and road. She lives in Scotland where the weather is fickle so needs to be prepared for all conditions.

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