Micro puff down jackets are nothing new, Rab seems to have broken into the mainstream with their micro alpine over the yeast few years, a walk along most UK high streets on even a slightly cool day will demonstrate that. It seems there are two types of gear junkies, those who cry a silent tear when in a downpour they pass someone who has yet to be introduced to how to adequately look after down and those who smirk.
All that said, when we saw Rab's Nimbus - a synthetic micro puff, using 3M Cirrus™ featherless insulation, we had to put it through its paces. We got our hand on this guy around 6 months and have had it on virtually every day; walking, climbing, commuting, socialising etc. This truly is a do-everything jacket! If you have never had one before, it will quickly become your go-to everyday jacket.
The filling was the reason we were excited about testing this jacket, and we think it's great. Being synthetic there is no worrying about getting it wet, we have had it fully saturated and although we did notice a drop in insulation, it was no more than your standard PrimaLoft filling. In term of loft after circa 6 months of constant use, we are struggling to see any signs of loss of loft. This is nice as, after 6 months of use, we have generally found that down insulation struggles from bunching up and separation, usually around the elbows. Although this isn't much of an issue with down as it is reversible, it is nice not having to deal with this with the Nimbus.
With regards to the overall insulation offered by the featherless Cirrus™, although there is not a huge amount in it (3M claim that Cirrus™ is equivalent to 600FP down), down insulation still wins for warmth as it is available with more loft (i.e. 750FP provided by the Rab Microlight). Overall, we would evaluate the synthetic down in the Nimbus as being a middle house between higher loft down and the more traditional PrimaLoft type insulation.
The jacket itself performs well in the field, as you would expect from Rab. It is a stripped back piece, elasticated cuffs and hood. Minimalist elasticated adjustable hem, 2 outer pockets and a single inner pocket, nothing to write home about, just good, well designed, features. One thing to be wary of is that the jacket uses a Pertex Quantum outer fabric, which keeps the weight down but is not particularly resistant to abrasion.
At 455g (men's medium) this makes a great mountain insulation layer, in awful and wet weather, we would recommend paring the jacket with a hardshell. The fit of the jacket is reasonably athletic so is suited as a mid-layer rather than a go over everything belay jacket.
Things we like: Great synthetic insulation, versatility.
Things we don’t like: Cost, weak outer fabric.
Succinct Gear Reviews are a collaborative team of reviewers based in Glasgow, Scotland. They have varied interests including; hill walking, climbing, mountaineering, camping, backpacking, kayaking, skiing, mountain biking and running which make them suited to reviewing a host of different outdoor products.