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The Giant Illume Mid-Thermal Long Sleeve Jersey will certainly get you noticed on the gloomiest of days, and its fabric will also keep you warm and relatively sweat-free. It offers comfort and performance for not a lot of money.
I'm not normally a huge fan of bright yellow jerseys as they tend to have that 'high-vis' look about them, but the Giant Illume manages to carry it off, being bright enough to make you stand out against the background while still looking like a classy jersey.
As the name suggests, the Illume also has quite a few reflectives for riding after dark. The black armbands have fine reflective strips all the way round, which is mimicked by the rear tail gripper. There is also a reflective strip on the rear pocket and the Giant logo on the chest will also bounce the light back.
Giant refers to both ThermTextura and TransTextura fabric in the Illume's construction, describing ThermTextura as incorporating "all the benefits of TransTextura fabric by transferring body moisture from inside while insulating you from the cold air outside". I found it worked well: on mild days around the mid-teens centigrade I remained sweat-free even when working hard with a summer baselayer underneath. With the temperature heading towards freezing, the jersey kept me warm down to about 4°C with a long sleeved baselayer beneath. I tend to run quite warm, though, so you might need to vary your layering.
There is no actual windproofing or water resistance here, but that does make the Giant versatile as a three-season jersey for when the temperatures can fluctuate a bit on a spring or autumn ride if you are out for a long time.
The thinness of the fabric also means you can layer up easily with a jacket if it is cold and wet.
The fit is relatively close but not restricted to racing whippets; there's a bit of room and the shape is pretty flattering to an amateur cyclist's build.
The tail is dropped to provide plenty of coverage to your rear even when in the drops, and there is plenty of length in the arms too when you are at full stretch.
The front is arched up slightly to minimise bunching of the fabric and it also stops the bottom of the zip catching the material of your shorts or tights.
There is no zip garage at the neck, but the collar isn't actually that high so irritation isn't very likely. I would prefer a slightly taller collar to stop draughts, and for it to be a little closer cut to the neck, but that's the only real criticism I have when it comes to the overall shape and fit.
Sizing is realistic, more UK than Italian, and Giant's size guide seems accurate.
The Illume has three pockets at the rear, with the two side ones angled down slightly towards the edges for easier access when you're riding. They're still plenty deep enough to stop things being ejected on rough roads and there's plenty of tension in the fabric to keep it taut. I would have liked a zipped valuables pocket for this kind of money, but it's not exactly a dealbreaker.
Priced at £64.99 it is very similar to the dhb Classic Long Sleeve Jersey (£65) although I prefer the Giant's softer fabric and better fit. The Giant Illume feels like a higher quality product, but the dhb does get a valuables pocket and zip garage.
It's a fiver less than the very similar and also very good Lusso Terrain LS jersey.
Overall, I really like the Giant Illume jersey. It may be a bit basic compared to some that offer more features and more protection from the elements, but it does what it's designed to very well.
Warm and breathable jersey that'll help you stand out in the gloom
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road.cc test report
Make and model: Giant Illume Mid-Thermal Long Sleeve Jersey
Size tested: Medium
Tell us what the product is for
Giant says, "Featuring ThermTextura™ technology for superior heat retention, moisture transfer and quick drying, with fluorescent yellow and 360-degree reflective details to keep you visible day and night, Giant's innovative Illume long sleeve jersey provides both excellent visibility as well as superior comfort."
Tell us some more about the technical aspects of the product?
Fluorescent yellow with 360-degree reflective details enhances visibility day and night
Quick drying fabric featuring TransTextura™ technology provides excellent moisture transfer
Race fit, body-contoured to enhance performance
Raglan sleeve cut provides maximum arm movement
Soft, silk-like feel
Three secure, easy-access rear pockets
Full-length auto-lock zip
UPF sun protection
A realistic size for the British cyclist.
How easy is the product to care for? How did it respond to being washed?
The yellow fabric can stain if you don't wash it straight after your ride and allow the road grime to get ingrained.
Tell us how the product performed overall when used for its designed purpose
It is a very good three-season jersey that keeps you warm and sweat-free.
Tell us what you particularly liked about the product
The bright colour.
Tell us what you particularly disliked about the product
Neck could be a bit taller and closer.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
There is strong competition from the likes of Triban, but it holds its own against offerings from dhb and Lusso.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
It may be a bit on the basic side, but it delivers on what is most important: a very comfortable fabric that is warm and breathable, a performance cut, and a decent price. Overall, I think it's very good.
About the tester
I usually ride: This month's test bike My best bike is: B'Twin Ultra CF draped in the latest bling test components
I've been riding for: Over 20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed
As part of the Tech Hub here at F-At Digital, our senior product reviewer Stu uses the knowledge gained from putting well over a 1,000 products through their paces (including hundreds of bikes) to write in-depth reviews of a huge range of kit. After first throwing his leg over a race bike back in 2000, Stu's ridden more than 160,000 miles on road, time-trial, track, and gravel bikes, and while he's put his racing days behind him he still likes to smash the pedals rather than take things easy. Although, as he spends a fair bit of his time reviewing ebikes these days he's becoming an expert in letting the motor take the strain. He's also waiting for 23mm race tyres to make a comeback!