Macpac Nitro initial impressions and size guide

Marcus, thanks for posting the thorough review. I got a Nitro from iDownman last year. I’m 5-7, about 42-43 chest. The XL fits me like the L fits you. In other words it fits like Arc Teryx made it. Boxier Patagonia fits my old body better. I do love the performance of Alpha. I sweat greatly regardless of temps. I’m in north GA, where it’s always humid but never cold for long. The Nitro with Smartwool 150 wt. base layer is super for working hard on the climbs (this isn’t crazy New England climbs, but quite steep and relentless in number). My old Marmot windbreaker makes a very versatile system for this part of the country. I do keep a puffy or vest handy for stops. Still, for 6 ounces you can’t beat the versatility. I’ll get another Alpha hoody, but from Senchi via Instagram, or Timmermade which only does full custom for about the same money as Macpac.

Friends have the Nitro and I’ve tried them on in store. They are on sale pretty regularly as are many things at Macpac these days.

Really unless you spend most of your time on very groomed trails I wouldn’t trust it much. A vest version would be much more versatile, and durable I think for most people. The sleeves cop most of the abuse/harder to keep away from danger (like a twig….). Ive thought about getting Senchi or someone else to make one for me, but its probably not worth the effort given the trips I do. I’d probably be better off with a MYOG wind vest made of something like membrane from RBTR.

I took this on another short evening hike/jog last night up one of the local mountain fire roads.

It started out about 74* with the sun just setting and I finished around 65* in the dusk. No wind at all.

This time I wore the Nitro as my only layer and WOW I am really impressed with it as a solo shirt. Its much, much more comfortable as I now realize the armpit pinching was actually my Icebreaker 120 bunching up underneath it (and the icebreaker fits me well by itself, its just the Nitro is very trim fitting, which I actually LOVE when its not layered).

Basically I discovered I love the cut for a solo layer, but the cut is much less comfortable if you have anything under it besides a compression shirt. The Nitro has a true athletic cut (not an ‘american athletic cut’ which isnt form fitting IME). Its slimer in the waist and belly than current Arcteryx. I wish I could find more regular shirts cut like this! Everything american is baggy in the waist and belly.

Without a base layer the small neck did not bother me

I started out with a light jog up a low grade as I wanted to test its performance in warm weather with medium-high output. At jogging pace I think it was actually cooler than my usual ultra thin poly long sleeve shirts because any wind just goes right through the Nitro. It close to not wearing a shirt. I only sweat a tad and it evaporated quickly.

On the way down my dog was tired so we just slow walked. Temp fell to around 65, slightly damp air moved in. When slow walking, it was nice and warm. In my poly shirt I may have been a tad cool, but the Nitro was very comfortable.

So I’m revising my initial thoughts a tad. They almost need to offer 2 cuts – a Base Layer cut (the existing product) and a Layering Cut, which would just be cut a tad looser in the armpits and neck to allow for a base layer.

The Alpha Direct is very soft and nice directly against the skin.

I think this could actually stand up as a moderate-hot weather shirt if it was white/off white, into the 80’s, because it breathes so well.

Also after reading the recent article on Fleece performance, the summary seems to be that loft directly correlates to warmth, and weight has almost no correlation. Comparing the Nitro loft to other fleeces like a Arcteryx Delta (forget the modifier) or Konseal microgrid the Nitro has considerably more loft. I guess this is how they get so much warmth out of such a light garment!

Im totally sold on Alpha Direct and will be looking to pick up other AD hoodies like the Senchi or a custom shirt that accommodates base layers slightly better. Its by far the best active garment I’ve tried to date.

@mcimes

I have both the Nitro and another macpac garment, the Pisa, which is basically alpha direct with a pertex quantum air shell sewn over it.

It’s never cold enough in SE Australia to wear the nitro as a running top but in freezing weather the Pisa is something I put on straight after a run – i take of my running shirt, don the pisa  and sweat through it until I’ve cooled down.  I never get chilled with this jacket – sweat just seems to evaporate through it – and I am a heavy sweater.

The Nitro itself is active insulation par excellence for humid alpine Australian conditions of around freezing.   Also works very well as a sleeping base layer under a quilt.  A versatile top for sure.

I also have a large, but I am smaller than Marcus – 5’8″, 175ish. The large is slightly looser than I would prefer. I have always worn it over a base layer. I suspect a medium might be too small for my purposes, but if you want a “Base Layer cut” as Marcus says, you might try that size.

I shave my head, too, but haven’t had the Sticky Hood issue Marcus has.

I agree with Marcus’s thoughts on the temperature range. Nitro + windshirt (in my case, a Montbell Tachyon) is a great and versatile combo. For less weight than my R1, I get a lot more options to tackle a range of temps and conditions.

I agree that the Nitro seems like it could be fragile. But I’m afraid to test that, so I don’t know if it’s actually fragile or not.

EDIT TO ADD: Contrary to speculation I’ve seen elsewhere, Nitro + windshirt is not a puffy replacement. While the combo is warm, my puffy is warmer, particularly when sitting still in camp.

I recently got a Superior Fleece Brule in 90 wt Alpha. I’ve only worn it once, in 50F – conditions too warm for it. But I wanted to see how it would handle moisture, and so wore it next to skin under a windshirt for 1.5 hours at about 4.5 METs. Got very sweaty, which I expected. The windshirt was very damp throughout, but the Alpha was bone dry apart from the pits, which were merely moist. I was actually fairly comfortable despite all the sweating during this period, probably due to all the evaporative cooling going on at skin level, as I was not wearing a wicking baselayer.

I then took off the windshirt and wore the Alpha next to skin as the temps climbed near 60F for another 4 hours of hiking at same pace. Wind started picking up near the end and donned and doffed the windshirt a couple times, as needed. I was very comfortable during this period. 60F is obviously way too warm for 90 wt Alpha, but as mentioned above, the knit is wide open to a walking breeze.

I think Alpha works well next to skin when it’s warm out, as the evapoative cooling at the skin is very effective due to Alpha’s being a sieve. But I think next to skin probably will not work as well when it’s cold out, which is when I would actually wear Alpha in earnest. Then, Alpha’s lack of wicking action and tendency to leave perspiration on the skin would work against the wearer.

On the other hand, maybe it would work a bit like a mesh baselayer in winter – quite well. The inner surface of the Alpha 90 (which might be the same as Macpac’s) is a little bit furry, like a mangy, short-haired beast, and so may function a little like a mesh shirt (e.g. Brynje).

I plan to wear it next to skin as a sleeping shirt on a trip starting this week. At 5 ounces, it is just barely heavier than my lightest merino sleeping T, but it has a warm hood and is very cozy next to skin:) It will also be available to wear under a rainshell and I’ll probably wear it next to skin for that too, as the temps are likely to be 40-50F and a little evaporative cooling at skin level will probably be OK.

This is my first Alpha garment and I’m probably overly optimistic. We’ll see how I feel when stuff starts getting stuck in it.

I got my MacPac Nitro yesterday.  I am usually a medium and went with the Large after reading this thread, and having a discussion with idownman.  He is still helping people in the US get this elusive mid-layer, and was a pleasure to do business with.  Mine is the “Medieval” color, a dark blue.  The photo on the macpac website depicts the color accurately on my computer screen, and I am really happy with it.

Delivery was almost one month, so I had to plan ahead.  Weight was 5.5 ounces for the large, on my scale.

To me, the fit is like a medium with a couple extra inches in torso length, and generous length in the arms.  The hood has no adjustment, but fits my head and neck better than many other hoodies (like Kuiu), because there is adequate neck length sewn into the hood.