Castelli RS Superleggera Jersey

The RS Superleggera from Castelli is lightweight, but aimed at general riders rather than out-and-out racers. Castelli says it uses fabrics and tech from its pro race jerseys to offer excellent comfort at a very low weight, minus the uncompromising focus on pure speed. And it works rather nicely. If you're off to the mountains and looking to cut grams wherever possible, this comes in at a barely-there 106g (compared with a more typical 150-180g for a summer jersey). Unlike some other lightweight jerseys we've tried, there are really no significant compromises to hit that weight.

Cut from a range of diaphanous fabrics, Castelli says this (along with most of the rest of its output, in reality) will fit best on those with "more athletic body types", but it is notably more forgiving than some of their racewear and all the better for it (assuming time trials aren't why you bought it). I'm generally a large in Castelli sizing, at 6ft 2in, a shade over 80kg and with a 39in chest, and I found the fit to be spot on here. That's not me in the pictures, by the way.

The temperature round these parts hasn't yet reached the giddy summer heights, but I found that paired with various base layers this was pretty spot-on for the mid-teens of spring afternoon riding; it's certainly not something you'd have to save for the hols abroad.

The Futura fabric (the blue bits) is really soft and light and very comfortable against the skin. It is pretty stretchy in the horizontal direction, allowing it to fit a wider range of body shapes. The black side panels are a highly breathable mesh designed to keep you cool when the mercury rises.

One of my favourite things about this jersey is the efforts that Castelli have put into pocket stabilisation. One of my bugbears with the ultralight Adizero jersey was that if you put a phone (a good bit heavier than the jersey) in one of the two side pockets, it pulled the jersey round to that side.

No such issues here thanks to two great pieces of fabric engineering. Firstly, there's a more compressive 90g stretch fabric used around the lower part of the jersey (the black part) which hugs your lumbar region and holds the jersey and the contents of the pockets nicely in place. Secondly, there's an inner layer of "3d mesh" on the back whose job is to provide vertical support and stop sagging. This covers the whole area between the seams that run up to the shoulder blades, and the mesh has plenty of horizontal stretch to avoid pulling tight across the shoulders but almost none of our old friend, vertical compliance. What that means here is that the weight of whatever you've stuffed in the pockets is supported right up your back to your shoulders, and it works a treat.

Castelli says that whereas the pros have team cars and hence don't need to load up their pockets, they recognise that the rest of us generally need to carry more than a couple of gels, and that led to the design of this jersey. The two side pockets are big enough to swallow a large modern smartphone and the centre pocket could take a pair of leg warmers or a lightweight shell or gilet. They've also included a zipped valuables pocket on the right-hand side for keys or coins, emblazoned with the words "You know you're getting an unfair advantage".

Unfair or not, (and you're certainly paying a fairly handsome price for that advantage), this is a really well-designed summer jersey. Yes, it is very light, but for me that's not the main point here, as it's also a super-comfortable and practical top for sunny days out. £115 is a big price for a summer jersey, a little less than what Rapha asks for its Pro Team Lightweight jersey, and may well be more than you're willing to pay, but if you're in the market for a primo "general purpose" warm-weather top (as opposed to out-and-out racewear) then I would certainly recommend this. It's debatable whether saving 50g off the weight of your jersey is really a worthwhile endeavour, but if it can be done without gratuitously compromising the other functions of a jersey, then why not? The RS Superleggera is available in a handful of fairly muted colour combinations.

Verdict

Ultra-light without the usual compromises on practicality - a lovely summer jersey for the mountains