What's My Castelli Size? A Guide to Cycling Sizing

By Stan Portus –  15 March 2021

There are several things to consider when choosing which size garment to buy. The first is physical measurements, but then cut, fabric choices, and intended use all play a part too. Read our guide to the sizing of Castelli’s different garments and the key things to look out for.

Previously we wrote about why Castelli comes up small when compared to other clothing, looking at how the history of different sizing conventions, changes in style, manufacturing and fabric evolutions has led to differences between the fit and the shape of garments across sporting companies, and generally in pret-a-porter fashion too.

Now we thought we would turn our attention to helping you decide which size Castelli garment is best for you.

The first thing to consider is physical measurements. Taking your measurements with a tape measure and matching them against Castelli’s size charts is the best way to check which size to go for. If you do this the fit will be exactly as the Castelli pattern engineers intended. But there are also other factors to bear in mind to ensure you get the fit that, most importantly, you desire.

You can view our dedicated Castelli Size Guide page for measurements, but we have put together a run through of the essential things to consider here. This covers how kit is tailored to the demands of cycling and consequently fits the way it does, how fabric choices affect fit, and the specific things to look out for with different types of garment from jackets to bibs.  

A cyclist photographed side on while riding out of the saddle and wearing the Catelli Rapido Jersey and Competizione Bib Shorts both in green

Designed for Riding

Within the Castelli range there is a variety of different jersey and jacket cuts suited to different forms of riding. For instance, the Aero Race jersey is designed to save every possible watt, so it has a closer cut and relies on stretching more. Whereas the Maison Jersey is designed to be comfortable all day long, so it has a slightly looser cut to be more accommodating and relaxed.

This means that when you come to try Castelli kit on, garments may differ in fit due to their intended use. The best way to establish whether a jersey or jacket will be rib hugging or afford you a bit more room is to have a look at the product descriptions to establish whether the item has been created for flying along at warp speed or for long and winding adventures.

There are subtle differences between Castelli’s jerseys, but all are ultimately designed to achieve a close to body fit. This is because having the jersey close to the body enables the fabric to wick moisture away more effectively, which ultimately keeps you drier and better regulates your body temperature.

With garments that are designed for aerodynamics and racing there might be a temptation to go up a size in order to achieve a looser fit. This is of course totally acceptable, but it is worth noting that the aero advantages built into the garment will be compromised.  

Changes in Sizing  

There are a couple of things to bear in mind when considering the size of a jacket or vest.

Firstly, you will be most likely wearing it over a number of layers. Whether that’s a winter jersey or Castelli RoS garment and thick winter base layer, or simply a thin summer jersey.

Secondly, whereas Castelli’s jerseys and shorts are made from high stretch materials, its jackets tend to be made from less stretchy fabrics or GORE-TEX® meaning they are less accommodating.

Because of these two factors we recommend considering going up a size, especially if you are buying a jacket for your winter riding and especially if you are intending to use it as an extra outer layer over a jersey. Otherwise, we find that RoS garmets, especially Gabbas and Perfetto Light Jerseys, correlate to jersey size. 

Bib Shorts and Tights

Bib shorts and tights work best when they are like a second skin. A snug fit is essential when it comes to Lycra bottoms. This will ensure that the seat pad will stay in the right place and will minimise any chaffing.

Castelli’s bib shorts and tights use aerodynamic fabrics and offer mild compression to help your muscles work, so a snug fit will also mean you make the most of these design features too.

Shorts and tights sizes don’t necessarily correlate to jersey size. Many riders find they either go up or down a size dependent on body shape. And remember that the length of the bib straps is designed for your riding position.

There are many different shorts and tights in the Castelli range suited to riding far, on the road less travelled, or through the depths of winter. Read our men's and women's bib short guides to find out more.  


Castelli warmers are designed to match up to your jersey size. Due to warmers using high stretch material you may find that you want to go down a size to achieve the perfect fit, but we recommend that you don’t do this with Nano Flex Warmers as this will compromise the warmers’ water-resistant qualities.

To give you the best sense of which size warmer is best for you Castelli provide sizing based on the same S, M, L sizing of jerseys and shorts, but on weight too. 

The Best Way is to Try Kit On

No matter what clothing you’re buying, the best way to establish whether it’s right for you is by trying it on. We’re talking sizing here, but also design, style and feel.

This is why we offer free returns. If in doubt you can order two or more sizes or colours and return whichever item isn’t right for you. All we ask of course is that you keep all the tags on, open packaging carefully, and keep your undies on when trying any shorts or tights.

Because Castelli kit is designed for riding, when you try it on it is best to assume a riding position. You can do this by extending your arms, bend at the waist, lift your head as if you’re looking at the road ahead, and lower your back slightly. That jersey or those bib straps that felt a bit snug will now feel exactly right for your next adventure.  

Castelli Size Charts

The Castelli size charts give precise measurements for each size, with the value being the maximum measurement for the size. You can find out more on our Castelli Size Guide page.

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