Polartech Alpha - do I need it in my life ?

I have a Fox jacket and salopette type trousers (Profire Alpha I think the range was called) that use it and I think it is excellent.  Does need to be sub 5 degrees before I’d wear them, maybe less for the trousers, but does a very good job of temperature/sweat regulation for me.  

Long sleeve baselayer coupled with Polartec Alpha vest/gilet is a very versatile combo I find.  I run hot normally and find this ok to mid-teens temp wise.  I use a Mountain Equipment with Alpha front and grid fleece back.

I've used Alpha a fair bit, mostly these days it seems to be the Direct - ie: fluffy version, the original stuff was basically this, but sandwiched between an outer and liner fabric, the liner fabric seem to have died a death. 

My take is that it's fantastic for cold weather, active use. Wicks really really well, dries fast, tends to use an air-permeable rather than fully windproof outer layer, which also helps with breathability. So yes, my take is that it lives up to the hype.

That said, if you run hot, you will still get warm and still sweat, you'll just get less enduringly soggy in the process. Obviously you also need to match it to a fast-wicking baselayer for it to work properly, merino or cotton will tend to hold moisture rendering it all a bit academic. You could, I guess, wear Alpha next to skin, but I've never done it. Maybe I should.

Downsides? The Direct variant sheds. I have two identical Outdoor Research hoodies. One is brand new, one has been worn and washed regularly for several years. The difference in loft / thickness / fluffiness between the two is stark. All that missing fibre has gone, presumably, down the drain, which I don't feel good about. Maybe washing it on a delicates cycle would have helped. Some is probably down to wear abrasion. So it's not super, long-term durable.

I also think that while it's an amazing walking and mountaineering solution, it's possibly too warm for mountain biking for a lot of people, but only you know how hot you run and what you normally wear. I find it really good for riding an e-mtb in cooler conditions though with lower heat output/effort levels. Still using a first gen Rab Polartec Alpha hoodie for that. 

Overall it's really good stuff, kind of like a much lighter, more packable, less OTT pile/Pertex, Buffalo-type solution for the 21st Century. 

It's one of my favourite fabrics. I used to run a shop selling lots of Japanese outdoor brands and they loved it as it was so breathable and lightweight.

With a shell over the top it's incredibly warm for the weight. As soon as you take the shell off/ open it then it will dump heat and allow really fast airflow.

Very packable too.

Have a look at the Houdini Pace Flow tops - uses Polartec Power Dry Mesh which uses a continuous filament yarn (not fluffy) to recuce shedding and microplastic pollution. Also works well.

I've got a gilet and a jacket, both Mountain Equipment.

The gilet is Alpha front/grid fleece back and I basically live in it working from home all winter - adds just enough warmth. Its a good midlayer for proper cold days on the bike, but also gets worn skiing and for winter walking/climbing. Packs up small.

The jacket is a little less versatile - needs a long sleeve base layer underneath as a minimum (the lining of the sleeves feels chilly otherwise #neshAF). Its not one of those bits of kit that makes you feel warm just by putting it on, but its great for keeping the heat you generate in. I've ended up using it as an outer layer for most of this winter's non-biking outdoor expeditions, (good weather!) as it vents well enough I'm not overheating uphill, but is warm enough for walking back down again. Never used it on the bike - although it would make a good emergency layer if I was going out in proper bastard cold conditions.

I'm skinny and feel the cold, so your mileage may differ...

I really rate it. I use it a lot and have quite a few different tops in this fabric, maybe 6? Lined and unlined, gilets and fleece type jackets

Used for walking and biking. Absolutely agree with needing a good base layer underneath (best one is Brynje mesh), and for biking will need a windproof over the top of all the warmth goes as it's so breathable that

Don't let benp1 show you his mesh base layer in the pub. It's a sight you will never recover from. 🤣 

Oh, and I have a Spanish (Trangoworld) Alpha gilet, intended for ski mountaineering that is great on the bike.

I'd second / third / whatever an Alpha gilet. I have a DHB one that I use both as a warm gilet, but also a cold-weather mid-layer that works really well with minimal weight and bulk if you do want to stow it away. 

Looks like I may have to extend my wardrobe 🙂

I have a few tops / jackets and gilets with Polartec Alpha insulation - it really is the dog’s doo-daahs for active wear in colder conditions the ability to wick sweat away and keep you dry and warm is quite remarkable in comparison to something like merino which turns into a soggy, damp mess. It also compresses/packs away to nothing - I’ll often take two tops on a mountain run and change over at the top. 

Avid user here too, several bits of Polartec Alpha kit (including a dhb alpha cap now i think about it!)  Agree with all the comments above but probably my standout item is a recently purchased Rab Alpha Flash Strike jacket. Basically just a simple single layer fleece made from Alpha Direct (no shell or lining).  Not best for riding if worn as an outer layer as it's vulnerable to brambles etc but is great under a thin windproof. I'm defo looking at Alpha Direct hoodies now...really versatile.