Castelli Aero Race 5.1 Jersey FZ

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.

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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.

Verdict

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