Rab Microlight Jacket Review

I'm curious about the 1.5" spacing of the horizontal quilting/baffles that you see in a lot of these down jackets (Rab, Patagonia, Mtn Hardware, North Face etc).

It seems to me that this is less efficient than using wider baffles (ie. Montbell) because this single layer quilting reduces the loft to zero at every line of stitching. Wouldn't less be better to a certain extent?

Is this done for style reasons? It seems excessive for simply keeping the down in place.

Love the goat(s) pic (and caption)–kudos to Janet!

Great review, as usual, Will. This category is getting crowded with fine contenders.

Cheers,

Rick

Dan,

Yes, the neck is too loose on Will. Will’s garment reviews are my favorite BPL content. He analyzes garments differently than I do but, I never fail to gain valuable additional insights from his reviews. After his highly recommended review of the WM Hooded Flash, I just had to try one on… I hated it. In a large measure this was because it fit me very differently than it fit Will. The size that maximized my torso warmth (see below), had hood dimensions that were totally ineffective. Compounding that, there were no adjustments to alter any aspect of the fit. It was my most recent reminder that “size matters”.

For any jacket to achieve its maximum insulation potential the neck has to seal, as does the wrists, and waist. Otherwise you have "chimney effect" heat loss when inactive. As your body heats air around your torso, it rises and goes out your neck. This in turn actively draws cold air up from the openings in the waist and wrist area.

You want the body of the jacket to be loose so as to maximize the garment warmth. The air space between the jacket and your next inner layer acts as additional insulation up to a max of about 3/4”. If you are moving, then the “billows effect” will pump both excess moisture and warmth out of your jacket. This is the reason that a down jacket doesn’t loose its insulating value in environments which it would be less than optimal for a down sleeping bag. For UL backpacking you normally only wear your insulation layer when your relatively stationary. Consequently, the warmth doesn’t billow out when you most need it; for example cooking breakfast or dinner. As you become more active, then your MET rate goes up and you want the billows effect to extend your thermal neutral range.

I alter the neck and wrists of many of my jackets to achieve their full warmth potential. All that is required is a needle, some polyester or nylon thread, and about a half hour of time. A neck looks best if it is taken in at both shoulder seams. If you take it in by using a single seam in the back of the neck, you will get a "hump back" material blossoming below the seam. Pin it and then try it on to insure you have the proper size prior to sewing.

The insulation value of an air space falls off rapidly when the air space is any measure thinner than 3/16 inch. The thickness of the insulating air films on each surface is reduced. The R value increases up to about ¾ inch when air convection in this space begins to offset any increase in distance between the surfaces. Although not relevant to jacket fit, the curve remains fairly level in this range with the insulation value near 1 until the curve exceeds 4 inches. Beyond 4 inches, convection currents disturb the air films and cause the R value of the air space to decrease.

I own a Microlight Vest from Rab and am very happy with it. I experienced the same issue with loosing down, but its not too bad. In the summer I also use it as a pillow at night, and in the winter I layer it with my Klättermusen Loke for some very nice warmth. Great piece of UL gear, for a good price.

Richard, would you be willing to hazard an estimated CLO for this jacket?

Reason I ask is I've always backed away from low loft down things (OK, this one might be considered low-medium loft) because the fabric weight is much more than the insulation weight … diluting the value for the $$$ paid for good quality down.

The outer shell weighs 1.3oz/yd^2 and the inner (30d) probably 1.1oz/yd^2 (1.2-1.3 if it contains ANY DWR) … easily more than the weight of the down (which I might guess to be around 1.5oz/yd^2 based on Will's data of 4.4oz of down fill in a size large).

This jacket seems very heavy compared to my Backpacking light cocoon

My Cocoon is my favorite piece of year. I can't believe the warmth it provides.

Like the Yeti Purity Jacket, there are so many horizontal baffels on the Rab Microlight Jacket, and I wonder why just like Dan said before. It makes no sense – its heavier (more stitches) and colder (more cold spots), and it is not necessary (see PHD Utra Down Vest: http://www.phdesigns.co.uk/product_info.php?cat=111&products_id=202 wich can cope with only 7 horinzontal baffels). Taking the loss and the medium quality of the down into account (PHD uses 900 cuin), this jacket is not the real winner for me. Or am I missing something maybe?

I'm puzzled why the fill-power wasn't explained better. Rab use European fill-power ratings, so 750 EU is equivelant to 850 US. More details on this Rab page HERE

"I've a phd UL on order – 900 EU fill power!"

How many ounces/grams of down? I'll bet you don't know? ;)

PHD gear does have a good rep, but their lack of info stops me buying their gear. Even if you email them to ask how much down they use in a particular garment, they won't tell you.
It's just my gnarly nature. I want to know what i'm buying, especially if it is very expensive!

… meant to add. If you do their 'design your own bag' you can specify EXACTLY the quantity of down. If the prices aren't crazy I'll be getting a summer quilt when they launch them – I'm very impressed with their stuff. They are like the MLD of the UK but with worse communication!