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Kalf Flux Lightweight Jacket



A few small niggles mean it's not perfect, but a very good showerproof jacket with many plus points

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Kalf's Flux Lightweight Jacket proves itself to be a very capable showerproof jacket, with excellent levels of breathability thrown into the mix.

  • Pros: Lightweight, decent cut and slim fit, breathable
  • Cons: Not all-day waterproof, zips difficult to work, packability

Kalf is developing something of a reputation for creating stylish, great value cycling kit. Sold exclusively through high street store Evans Cycles, its more direct sales model means it can undercut rivals on price while still hitting its performance targets.

> Find your nearest Evans store here

So, when I got told that that the Lightweight Jacket costs a sizeable £110, immediately alarm bells rang: to meet the usual good value checkpoint, it would need to perform seriously highly. Thankfully, in most respects it does exactly that.


While not a truly waterproof jacket in the same way a premium Gore Shakedry jacket is (at twice the price), there's plenty of water resistance here to deal with showers. Heavy ones too, I found, with a couple of pouring rain bursts lasting around 30 minutes each in the Basque Country and at home well dealt with, with water beading off a treat.

Only beyond this timeframe does the surface begin to wet out, yet it remains still resilient to water ingress. Taped seams inside the fabric ensure there's no leakage in this area, while the fabric itself is surprisingly breathable too.


I say 'surprisingly', because often it's breathability that's the first thing to go when prices fall or the brand becomes less 'marque'. However, Kalf has selected it wisely, and it proved throughout a day of on-off rain showers that it could keep me relatively cool despite working up climbs.

Heading down the other side of hills, the jacket is also able to keep the chill off, even though it's not like a true windblocker thanks to its permeability to air. The zip is a sealed style, with a flap underneath to help stop unwanted draughts.


Another really important thing about a technical jacket like this is the cut. A flappy or ill-fitting jacket can be a real ride-ruiner. However, Kalf has given its Lightweight Jacket a slim cut that leaves little spare fabric to flap around while still fitting well around my wide shoulders (it's me in the photos, folks).


The sleeves are long enough to cope with my longish wingspan too, with a dropped tail suitable for those who are long in the body. The wrists have narrow cuffs to stop water and draughts sneaking up, while helping to keep them in place.


The elasticated hem complete with silicone band around the waist does the same job, although compared to the rest of the garment it's quite chunky, adding some bulk to the jacket when you attempt to pack it down. You'll need a large jersey pocket to fit it in. The high collar doesn't help matters in this respect either. That said, it's very comfortable, with the waist staying fast against the body, and fleece backing on the collar.


To clarify, these bulkier elements do a great job of improving comfort and overall functionality; it's just that they're a touch bulky to make the jacket truly packable, even if they don't add much weight (the jacket comes in at a svelte 140g for a medium, 10g more than claimed).

I mentioned that the zip is sealed to ensure it keeps out water and wind, but at the same time this makes it difficult to work with one hand because the main fabric around it is so light. You need to be very comfortable riding with no hands so you can use your other hand to anchor the bottom in place if you want to don or remove it on the move.

> Survival tips for cycling in the rain

I've never been the greatest at this skill (more practice is definitely needed!) so I needed to stop each time to get it on and off, but small adjustments with small tugs are possible on the move.

On the practicality front, there's a zipped pocket on the right hand side of the body – sealed against the elements – and there's a handy loop to hang it up when you get home or to the café stop. You also get Kalf's distinctive iridescent branding on the tail section for a bit of added visibility, on top a small logo just off centre under the collar.


In terms of value, it's £20 cheaper than the similar weight Sportful Hot Pack NoRain, although Sportful gives that a 5/5 rating for waterproofing so you're (possibly) getting more protection. You can pay less, though: the Kalf is getting on for twice the price of the top-scoring Showers Pass Ultralight Wind Jacket, which weighs about the same, offers great protection against light rain and showers with a durable water repellent (DWR) outer, and costs £65. The even lighter Pearl Izumi Pro Barrier Lite also offers impressive weather protection and breathability, and is £30 cheaper than the Kalf.

> Buyer's Guide: 11 of the best windproof jackets

Despite the niggles of not being easily packable despite the lightweight fabric, and zips that can be difficult to work, the Kalf Lightweight Jacket is a good all-round performer when the weather turns. It has a slim cut for fast riding and is comfortable to wear, is waterproof in all but the most prolonged rainfall, and very breathable.


A few small niggles mean it's not perfect, but a very good showerproof jacket with many plus points

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Make and model: Kalf Flux Lightweight Jacket

Size tested: Medium

Tell us what the jacket is for

Kalf says: "The Flux Lightweight Jacket has been created for mobile weather protection. Created with unpredictable conditions in mind – such as spring rides or adventures in the mountains – the jacket is supremely light and stashable.

"The medium size weighs just 130g and the jacket's fabric is windproof and highly water-resistant, with excellent flexibility. Water resistant zips and a brushed polyester fabric inside the collar add to the comfort the jacket provides. An articulated cut with a lower back panel ensures good coverage even in race positions on the bike – and the overall fit is snug (although still highly flexible) to ensure optimum weather protection and aerodynamics. Other details of the jacket include a reflective detail and elasticated cuffs."

Tell us some more about the technical aspects of the jacket?

Evans says this about the jacket:

- Advanced Fabric Permeability - No compromises have been made in selecting the most advanced fabrics that push the envelope of maximum breathability. The highly advanced fabric allows sweat in the form of water vapour to leave at a high rate of transfer through the fabric, keeping you dry, warm and comfortable.

- Taped Seams - When sewn, tiny holes pierce the waterproof membrane of the fabric shell. In order to make the garment 100% waterproof, the holes need to be covered using seam sealing tape. The tape is bonded using a specialist machine that uses hot air at a temperature, pressure and speed defined by the combination of tape and fabrics.

- Reflective Detail - Our iridescent reflective trims and logos make for a unique aesthetic but also bring visibility to our products without visual assault.

Rate the jacket for quality of construction:

It certainly looks the part, with good quality taped seams and sewn hems.

Rate the jacket for performance:

It's a step shy of fully waterproof on a full rain ride, but then again it doesn't claim to be. Very competent in repeated showers and breathes very well too.

Rate the jacket for durability:

The lightweight fabric seems durable enough and it doesn't catch on rough surfaces.

Rate the jacket for waterproofing

A step shy of full all-day waterproofing, but still very good, and great as a changeable weather shell.

Rate the jacket for breathability

For me, this is one of the most surprising(ly good) aspects of this jacket.

Rate the jacket for fit:

The fit is definitely performance-orientated, but there's enough space for wider shoulders without pulling up the arms.

Rate the jacket for sizing:

Comes up as expected. A medium is spot on for me – a close fit, but that's preferable to a baggy parachute.

Rate the jacket for weight:

140g isn't bad, but the thicker waist hem surely adds a little more than is absolutely necessary, which impacts on packability too.

Rate the jacket for comfort:

The fit largely informs this, and that's very good. The collar has a fleece backing for added comfort.

Rate the jacket for value:

Not quite Kalf's usual standard for value, but still on the money in terms of what you get. 

How easy is the jacket to care for? How did it respond to being washed?

Technical washing is the way to go with this one to maintain performance.

Tell us how the jacket performed overall when used for its designed purpose

Very well, all things considered.

Tell us what you particularly liked about the jacket

Weight, decent cut and slim fit, breathability.

Tell us what you particularly disliked about the jacket

Not all-day waterproof, zips, packability.

Did you enjoy using the jacket? Yes

Would you consider buying the jacket? Maybe, although I'd be tempted to fork out more for a Gore Shakedry jacket for ultimate protection and breathability.

Would you recommend the jacket to a friend? Yes

Use this box to explain your overall score

It performs really well as an all-round showerproof jacket, and even though the price isn't as competitive as other Kalf kit we've tested, it still warrants an 8 overall in my opinion.

Overall rating: 8/10

About the tester

Age: 28  Height: 188cm  Weight: 80kg

I usually ride: Canyon Ultimate CF SL 9.0 SL (2016)  My best bike is:

I've been riding for: 5-10 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: time trialling, club rides, sportives, general fitness riding

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