Castelli Unlimited Puffy Jacket review – lightweight warmth for cooler rides

Castelli’s Unlimited Puffy Jacket uses Polartec Alpha and a windproof shell to hit a sweet spot of warmth and breathability

Man wearing Castelli Unlimited Puffy gravel Jacket in front of hedge
(Image: © Sean Fishpool)

BikePerfect Verdict

It doesn’t always feel so warm when you stop, but in use, the lightweight Unlimited Puffy jacket hits an extraordinary balance of warmth, windproofing and breathability.

Pros

  • +

    Light, unobtrusive warmth

  • +

    Works in a range of temperatures with just a base layer

  • +

    Trim but not roadie fit

Cons

  • -

    The unlined stretch panels lose heat when you stop

  • -

    Expensive at full price

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If you're looking for a jacket for gravel or bikepacking, then the Castelli Unlimited Puffy Jacket could be what you're after. Castelli say this option is ‘for when the challenge is distance rather than speed’, but that suggests you shouldn’t put any effort in lest you overheat. I’d describe it as a great ‘messing around all day’ jacket. Wearing it in winter and spring between about 3 and 12C with just a base layer underneath, you could pretty much forget about it. And that’s even in light rain, despite it only being a windproof, because it stays pretty warm when damp, and dries out super fast.

It packs down easily too – it would just about fit in a jersey pocket. The secret to most of its magic is the super-light Polartec Alpha Direct insulation, but Castelli has done a nice job of designing it into a good-looking and very usable top.

Rear view of rider wearing Castelli Unlimited Puffy gravel Jacket

From the rear you can see the unlined stretch panels behind the arms and on the side body (Image credit: Sean Fishpool)

Design and Specifications

The Unlimited Puffy is mostly made from a very thin windproof microfiber outer shell, lined with Polartec Alpha Direct – that’s the orange fluffy parts in the photos. The panels on the side of the body and the backs of the sleeves are made from an unlined slightly stretchy fabric. It weighs 217g for a size medium, which is about the same as a very lightweight waterproof jacket and not much more than a thick base layer.

The whole thing is cut to have a ‘cafe and gravel’ fit, which I really liked. I probably wore it half a size looser than the more shrink-wrapped look that Castelli’s models rock, so a medium for me at 173cm and 66kg was brilliant – just right on the shoulders, arms and body length; a very tidy fit but room for easy movement and layering options. I barely noticed I was wearing it.

Close-up of Polartec Alpha insulating fabric

In Polartec Alpha, fine threads are durably attached to a lace lattice (Image credit: Sean Fishpool)

Polartec Alpha was designed for the US military to be warm and light, breathable and good when wet. It’s basically a very open lattice of threads (like a technical lace curtain) with ‘lofted fibers’ attached to it. To you and me it looks like it’s already threadbare, but its genius is that it manages to be this finely woven while staying durable. 

Because the wind would go straight through it otherwise, Polartec Alpha needs a windproof outer layer and that’s what traps the warm air against your body. Water vapor can pass easily from your body or your base layer through the insulation, and the fibers can wick moisture too.

In terms of features, the Puffy Jacket has a zip pocket in the chest, and two open pockets in the back with another zip pocket underneath one of them. The open pockets have flaps on the top but I’m not sure I’d risk anything valuable in them over rough ground. The waist band at the back has a nice amount of stretch to keep it in place.

Inside view of Castelli Unlimited Puffy gravel Jacket

The orange insulation lines most of the jacket (Image credit: Sean Fishpool)

Performance

I really liked the Unlimited Puffy. I’ve been reaching for it a lot, and wearing it in a wider range of temperatures and levels of drizzle than I thought I would.

At first, you get a strange sense of disconnect when you know it’s cold and you feel like you’re not wearing much because the top is so light, and yet your body feels just right. Most of the time, with the right base layer underneath, an occasional up or down with the zip was all the temperature regulation that was needed. When heat did build up on tough hills, it cleared quickly, so there was no need to yo-yo between jacket-on and jacket-off.

Rear pockets of Castelli Unlimited Puffy Jacket

The open pockets are generously sized and there’s a zip pocket beneath (Image credit: Sean Fishpool)

The one thing I struggled with a bit was the thin uninsulated panels behind the arms and on the sides of the body. They clearly contribute to the light weight, breathability and freedom of movement that I liked so much, and I wouldn’t change it because of that, but below 5 or 6C I needed to pull on another layer fairly quickly when stopped, to avoid losing too much warmth. I sometimes noticed this when cycling too, that the torso and the front of the arms were cosy while the backs of the arms were a bit fresh. It wasn’t a problem, just not what I’m normally used to. 

Cuff of Castelli Unlimited Puffy gravel Jacket

The cuffs are simple but comfortable and snug (Image credit: Sean Fishpool)

Verdict

I still haven’t worked out exactly what I’d need to pack for a cold bivvy trip alongside a jacket like the Unlimited Puffy – a thin waterproof, and something warm to pull on for snack stops – but I know I’d want to take it. The same with everyday mountain biking when it’s not pouring. The fit and the style are great, but it’s the ‘leave it on and forget about it’ quality that’s best of all.

Tech specs: Castelli Unlimited Puffy Jacket

  • Price: $335 / £280  
  • Sizes: XS, S, L, XL, 2XL, 3XL
  • Colors: Light Military Green/Dark Gray (tested); Nickel Gray/Dark Gray; Goldenrod/Dark Gray
  • Weight: 217g (medium tested)
  • Key materials: Microfiber woven outer shell with DWR; Polartec Alpha Direct insulation; Nano Flex stretch woven fabric panels
  • Eco credentials: Castelli doesn't highlight any specific eco credentials for this product but as an organisation is acting on its use of energy and emission, materials and packaging, and supply chain. More details here 
Sean Fishpool
Freelance writer

Sean has old school cycle touring in his blood, with a coast to coast USA ride and a number of month-long European tours in his very relaxed palmares. Also an enthusiastic midpack club cyclocross and XC racer, he loves his role as a junior cycle coach on the Kent/Sussex borders, and likes to squeeze in a one-day unsupported 100-miler on the South Downs Way at least once a year. Triathlon and adventure racing fit into his meandering cycling past, as does clattering around the Peak District on a rigid Stumpjumper back in the day.

Height: 173cm

Weight: 65kg

Rides: Specialized Chisel Comp; Canyon Inflite CF SLX; Canyon Aeroad; Roberts custom road bike