Spatz Heatr 4 Season jersey review

Spatz’s ultra-high-tech 3D-knitted jersey might just be the ultimate all-weather jacket for hard and fast riders with cash to invest in the best

Spatz Heatr Jersey review
(Image: © Guy Kesteven)

BikePerfect Verdict

Super high-tech seamless design provides jacket-level weather protection and warmth with jersey fit, wicking and weight. Limited pocket space and seriously high cost, though


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    Jacket-level protection and performance with jersey fit and weight

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    Unbelievably toasty for weight and bulk

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    Targeted 3D seamless fabric tech

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    Not really bothered by wind or wetness

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    Impressively sweat-shifting when it’s hot


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    Only two tight pockets

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    Fancy fabric means high cost

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Yorkshire-based Spatz has already set benchmarks with 3D-knitted, targeted performance base layers that deliver unbelievable warmth and wicking for their weight. Now the pro rider proven-and-developed clothing brand has added outerwear to its line. 

The Heatr 4 Season is the company's latest addition to the best mountain bike jerseys and arrived just in time for testing temperatures to drop into single digits, and initial impressions of fit and sweat-free weather-beating warmth mean it’s looking like it’ll be a firm favourite through fall and winter. However, potential downsides are the price and pocket capacity.


<a href="" data-link-merchant=""">Buy the Heatr 4 Season Jersey direct from Spatz

Design and aesthetics

Guy Kesteven wearing the Spatz Heatr Jersey, standing next to his bike in a wooded area

The Spatz Heatr jersey provides a snug fit that's super stretchy (Image credit: Guy Kesteven)

3D-knitted designs to capture warm air, manage wicking and create a mobile but supportive stretch fit are nothing new in base layers, but Spatz has definitely elevated the next-to-skin garment game with its Basez Range. 

The Heatr jersey takes learnings from those base layers and the Burnr gillet to create a super versatile base/mid/single layer jersey that seems almost sentient in how it responds to changing conditions.

The secret is a super-complex single-piece knitted body that mixes deep ‘pore’ stretch sections on the lower chest and flanks with honeycomb-reinforced lower panels. A wind-resistant shell fabric is then added over the upper chest and shoulders. The sleeves use an even more complicated weave, with slatted upper arms, extra mobile stretch sections on the elbow joint and then 3D-stretch panels around the outer elbow and extended wrists, which also boosts blood warmth just before it flows into your hands. 

Cuffs and collar are soft stretchy jersey that’s just tight enough to hug draughts away without choking, and you can still slide the arms up over the elbows if the day warms up. A slim silicone gripper helps keep the curved lower hem in place while the two relatively small back pockets use reflective chevron fabric. Meanwhile, the Spatz logo is woven into the spine to create a lighter, faster-wicking section up the back. So, while the price might seem ridiculous at first, you only have to look at the detailing up close to realize it’s a justified cost. 

Sizing also seems child-like at first until you experience how stretchy the construction is. It’s definitely designed to fit while riding, rather than resting, so don’t be surprised if it bunches up under your armpits and feels like you might have it on back to front before you get on the bike. 


Guy Kesteven wearing the Spatz Heatr Jersey shows from behind next to his bike, with a bike pump and inner tube sticking out of the left rear pocket

The jersey is a little light on storage space (Image credit: Guy Kesteven)

Depending how much you hauled it on in a hurry there might still be a bit of tugging and tweaking to be done to make sure everything sits where it should once you're rolling, too. Once I fettled through my small Heatr, it hugged me like a second skin when used alone, but there’s still enough stretch to handle a thin base layer underneath without starting to cramp circulation. The sleeves are long enough to pull right down onto your hands even if you’ve got gibbon DNA, and the hem doesn’t ride up and expose your lower back like some snug-fitting jerseys can. While we can’t vouch for any aero gains or losses from the various textured elements, there’s certainly zero flap or flutter however fast the descent or brutal the headwind.

It’s the fact that those headwinds or descents don’t seem to dent the exceptional thermal performance of this jersey that really separates it from the pack. Like other Spatz kits, it takes a while to warm up, so you can expect to feel underdressed at first if you’re heading out into a cold snap. Give it ten minutes or so, and it’s clear the Heatr is trapping your warmth with furnace-style efficiency exactly where it matters most. It’ll keep doing that seemingly regardless of what the weather is doing too, and I’ve hammered comfortably through sudden temperature drops and serious storm showers without even thinking of reaching for a shell. In fact it’s so warm that I had to get used to remembering that I was only wearing a single layer and not a jacket and base when I accidentally unzipped myself semi-naked at cafe stops. 

Thankfully, the structured weave doesn’t just manage stretch and trap warmth: the consistent contact also keeps the Heatr impressively sweat-shifting in a way that a looser fitting and/or laminated shell jacket just can’t compete with. That’s not to say I didn’t overheat when days warmed up, but even when I was wearing it as a single layer (and that was any time above a handful of degrees Celsius) it didn’t feel clammy or create instant cold spots when I started descending. 

In fact, the biggest mistake you can make is underestimating the warmth of this jersey, as you’re sure to end up either taking off an outer layer or stripping off a base from underneath sooner rather than later if you do. That’s not only inconvenient, it also highlights the only potential functional issue with the Heatr, and that’s the lack of pocket space. We contacted Tom Barras (Mr Spatz) about this and he told us: 

“The pocket design was very carefully considered. I wanted pockets that sit close to the body and hold kit nice and firm without it sagging down to your [butt]. Or having to sew extra straps into the seamless fabric and compromise its performance. I’ve tested samples with two, three and four pockets, and two worked the best by a long way. Plus we’d hope a user was wearing our cargo shorts, offering another three pockets.”

Obviously, you’ll have a better idea whether that answer works for you or not than we do, but don’t say you weren’t warned if you find yourself struggling for storage space. It’s also fair to point out that it’s not a flattering jersey if you’re carrying a significant amount of subcutaneous fuel either.  

A Spatz Heatr Jersey lying flat on the ground and open, revealing a honeycombe structure in the fabric interior

A variety of fabric textures are used throughout the jersey (Image credit: Guy Kesteven)


Spatz has clearly drilled deep into its pro riding and fabric development experience with the Heatr and the result is a truly outstanding combination of jacket-level protection with an aero jersey fit. Unsurprisingly, considering its hardcore origins, it’s especially suited to riders who want consistent comfort and core temperature whatever the weather throws at them, but hate stopping to change layers or top up protection with something loose or flappy. That focused performance does come at the expense of cargo capacity, however, which won’t work for everyone. Plus, however versatile and high=tech it might be, £200 is still a ton of cash.

Tech Specs: Spatz Heatr 4 Season jersey

  • Price: £199.99
  • Weight: 280g (M/L)
  • Colours: Black (Red and Blue coming soon)

<a href="" data-link-merchant=""">Buy the Heatr 4 Season Jersey direct from Spatz

Guy Kesteven

Guy has been working on Bike Perfect since we launched in 2019. Hatched in Yorkshire he's been hardened by riding round it in all weathers since he was a kid. He spent a few years working in bike shops and warehouses before starting writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.

Current rides: Cervelo ZFS-5, Forbidden Druid V2, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg