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Castelli Aero Race 5.1 Jersey FZ



A jersey that works better the hotter and faster things get, but the fabric could be softer

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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Castelli's latest Aero Race 5.1 Jersey FZ takes a lot of the aero details from its Speedsuits and combines them with the lightweight mesh construction of its Climber's jersey. What you get it a close-fitting, race-cut top that is unbelievably breathable on even the hottest of days.

  • Pros: Great airflow to keep you cool, taut pockets
  • Cons: Material isn't the softest against the skin

When it comes to weight and performance, most companies (especially those flogging cars or bikes) charge you a higher price for less of the first and more of the latter. The more stripped back it is, the more it's going to hurt the wallet. That's kind of what we've got here with the Aero Race 5.1. It's one of the most expensive short sleeve jerseys in Castelli's catalogue at £100, yet there is virtually nothing to it. That's right: just under £1 per gram.

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Joking aside, the Aero Race isn't excessively priced when you compare it to a lot of competitor's jerseys we've tested over the last 12 months. Rapha's Pro Team jersey, for instance, comes in at £140 for a similar build and weight. And Alé's PRR 2.0 Piuma uses a mesh construction like that of the Castelli and also shares the same price tag of £100. Like those, the price of the Aero Race 5.1 is reflected in its performance and overall quality too.


The underarms, side panels, back of the neck and main front panel all use a wide-knit mesh that really allows the air to flow through, keeping you impressively cool. I was thankful I chose the Castelli for a four-hour ride in the recent heatwave which found me exposed on the plain with temperatures nudging 29°C and not a cloud in the sky.


Even slogging up some of the steep climbs I could feel the breeze on my torso, and when descending the rush of air was actually quite refreshing.

The back is made from a much smaller mesh pattern which protects you a little more from the elements, especially the sunshine.


My only real criticism is that the mesh makeup of both fabrics doesn't feel as soft against the skin as other solid jerseys and if you do get hot and sweaty it can feel a little annoying, even when wearing a mesh summer baselayer underneath.

The pockets are made from the same material, but even though it is quite thin the pockets remain taut thanks to some elastication across the tops.


I had no issues with carrying a small mini-pump, multi-tool, tubes and a mobile phone in them without fear of them bouncing out. There are no zips or anything on the pockets; Castelli has stuck with just the traditional three and no small valuables option.

The hem is held in place by an elastic gripper that runs right the way around the jersey and does a great job of keeping everything in place when stretched out on the bike.


You get a full zip so you can regulate temperature even more and it finishes much lower at the neck than most normal jerseys. It's the same as you see on Castelli's SanRemo and Bodypaint Speedsuits: the idea is to remove the aerodynamic drag from a high collar, which can let air enter down the front and back of the neck where it doesn't fit close to the skin.


In the majority of jerseys I wear a size medium but with Castelli I always find it better to go up a size. Here, this large is a good fit: still close cut like it's designed to be, but without any feeling of being restrictive around the chest or stomach.

> Buyer's Guide: 18 of the best summer cycling jerseys

Quality-wise, as I said above, the Aero Race is pretty well made, and considering how thin the fabric feels it also seems to be durable enough. I've stretched it hard with my hands and I haven't had any issues with it ripping or any seams pinging.

This blue/cyan is one of three options along with grey/yellow and black/white, with each them looking quite understated with their subtle graphics and design. Castelli has another couple of Aero Race designs in its range – full reviews of both coming soon.


A jersey that works better the hotter and faster things get, but the fabric could be softer

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Make and model: Castelli Aero Race 5.1 Jersey FZ

Size tested: Large

Tell us what the product is for


After starting the aero jersey revolution in pro cycling, we've continued to perfect this piece. Version 5.1 builds on the race-leading aerodynamics while making the jersey more comfortable and durable. Updated fabrics on the front and back showed a 2-watt gain in the wind tunnel compared to the previous version. But it's not just aero; it's also extremely light, coming in at just 103 g. That's about 40 g lighter than a standard jersey and almost as light as our Climber's Jersey. Just like you, our pro riders are looking for comfort, and the lightweight polyester fabrics in this jersey dry nearly instantly, making this the go-to choice even for cool- or wet- weather racing, while the compression band around the pockets keeps them from moving or bouncing no matter how you load them up."

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

From Castelli:

Velocity dimpled fabric on front

3D mesh on back to prevent overheating

Mesh arm bands

Compression band around waist keeps 3 rear pockets in place

Silicone gripper elastic

Full-length YKK® Camlock zipper

Reflective heat-transfer viz strips

Rate the product for quality of construction:
Rate the product for performance:
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Rate the product for fit:
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Rate the product for value:

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

Thirty degree wash with no softener and no bleach, plus Castelli recommends line drying in the shade.

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

It certainly lets the breeze flow through when the temperatures are hot.

Tell us what you particularly liked about the product

Lightweight and breathable.

Tell us what you particularly disliked about the product

Mesh material isn't the most comfortable against the skin.

Did you enjoy using the product? Yes

Would you consider buying the product? Possibly

Would you recommend the product to a friend? Yes

Use this box to explain your overall score

If you ride or race hard in the summer months then the Castelli is a great choice as it is impressively breathable, plus there are the obvious aero tweaks. It's well made and against a lot of the competition quite reasonably priced. I would prefer a softer material, though, as I didn't find it the most comfortable against the skin, and this holds it back from scoring higher overall.

Overall rating: 7/10

About the tester

Age: 39  Height: 180cm  Weight: 76kg

I usually ride: This month's test bike  My best bike is:

I've been riding for: 10-20 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

With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!

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