Castelli Kit Temperature Guide


Getting to grips with Castelli temperature ranges to pick the perfect kit for every ride.


Castelli's obsession for cycling performance encompasses mile upon mile of testing in the Dolomites a stone's throw from HQ, so the team in Italy knows a thing or two about all-weather riding.

However, there's more to selecting the right kit than sticking rigidly to the resulting temperature range suggested on product pages

This is something we get a lot of correspondence about here at Castelli Cafe, so we've put together this guide to help you choose the right garments for the right conditions.


 Different riders prefer different Castelli garments in the same conditions
Different riders prefer different Castelli garments in the same conditions.

We're all different

Some riders run hot, others feel the cold. A cyclist with 5 per cent body fat will have different insulation requirements than someone who's neglected the turbo trainer over winter. Given Castelli's high-mountain playground and the fact feedback also comes from pro riders, the temperature ranges are skewed towards the slender more experienced rider.


Hill reps and potters to the cafe aren't the same

The intensity of your riding will help determine how much clothing you'll require for each ride. Castelli weights a product's suggested temperature range to its intended function, so a pure racing piece will have a much lower temperature rating (0 to 10°C) compared to a training piece of similar materials (5 to 15°C) on the assumption that intensity will be higher. It's similar to how an aero piece will have a much snugger fit than a training piece.


Ambient temperatures can mislead riders

This is a biggie. The temperatures that you normally see on weather websites or on your thermometer at home represent the temperature of the ambient air, but how you actually experience this temperature can vary wildly.

Wind speed and humidity can make a huge difference in how we perceive that temperature on the bike. For example, in winter a strong wind can feel much colder than the measured temperature would indicate. Conversely, on a humid day in summer, it can feel much hotter than the air temperature would suggest on its own.

Using the 'feels like' temperature provided by some forecasters is a good start, but even this doesn't take into account the effect of wind-chill when speeding along on your road bike.

During a warm sunny spring day at 15°C, most Brits will be out in shorts. But what if you have a prolonged descent at 40mph and it's a damp day with no sunshine? That ambient temperature of 15°C becomes -8°C with wind chill.

So, it's important to remember that temperature can vary from an ambient reading for a number of very different reasons: shade, sun, wind, humidity, even inversions (colder air sinking into valleys because it's heavier than warm air) – and don't forget altitude (see below).

All that's to say – don't take weather forecasts as a given for choosing what to wear on your ride.


Elevation's important

If you've ever ridden a climb like the Ventoux, you'll know that a balmy summer's day can turn to shiver-inducing chilliness by the summit this has a big impact on the descent as suddenly you wont be working and your adding windchill – so thinking about what sort of elevation you'll be tackling pre-ride can help inform your outfit decisions, what to wear and what to carry.

If there's no snow (or rain) falling from the sky and you're not stuck in a cloud, the temperature decreases by about 3.2°C for every 300m (1,000 ft) climbed. This means that at 1,612m of elevation gain, the temperature at the top of Ventoux is around 17.2°C lower than the bottom. If you're riding through clouds or it's snowing or raining, the stats change to about 2°C for each 300m gained, making the summit of Ventoux 10.7°C colder than its foot.

This is all to do with air density and short of a full-on science class, the result for cyclists is that whatever the conditions, it's going to get colder as your climb progresses – something to take into account when selecting your kit.


Conditioning plays a major role

If you're used to riding in Spain's 40°C August heat, then 15°C is going to feel very cold. On the other hand, if you have just been dog-sledding for two weeks at -20°C, 15°C feels very warm. No clothing temperature guide can account for people used to different conditions meeting in the middle – those riders are going to need a different wardrobe.


Some areas have a bigger impact on warmth

Some parts of the body have a greater effect on temperature regulation than others. If it's cold, wearing a neck thingy and longer gloves that cover the wrists will allow you to explore colder temperatures than the stand-alone temperature range given for your jacket alone.

Conversely making sure the air can get to your neck and wrists when it's warmer works in the opposite way, allowing your body to cool and maintaining comfort at the higher end of your jacket's temperature rating.

Other areas that have this effect are the temples (use a head band when it's cold), the knees and the ankles.

So if you normally suffer from cold hands and feet, you may benefit from looking at your lower leg and lower arm warmth making sure these areas are covered and and draft-free.


How to use the Castelli temperature charts

If all of that's just added to your confusion, here's the good bit – how to negotiate the Castelli temperature charts for British riding.

Always consider the lower temperature indicated as a guide for a skinny pro on a high-intensity training ride.

Use the higher temperature as a guide for the same lithe rider on a recovery ride.

We recommend that most UK club cyclists can knock 3 to 5°C off the range due to the natural toughness of the Brits, conditioning to the hardships of riding in the UK climate and erm - easy access to bacon butties!

So, if Castelli states 5 to 15°C for a product range, then most riders in the UK will probably feel most comfortable riding these items at 2 to 10°C.

Use current your items as a guide. If for instance you know that you're comfortable in a Perfetto LS jersey with a Flanders base layer at 1°C (the Perfetto is rated 6 to 15°C) and you're looking for a winter Jacket for riding in the -5 to 5°C range, buying a jacket rated -5 to 5°C you will likely be too warm. So get one rated at 0°C to 10°C. Likewise, if you can only wear the Perfetto when it's 10°C and above – and you're looking for a Jacket for riding at 0°C go for one rated -5°C and consider adding an extra layer.

Unless you know you run cold or need extra warmth, we recommend erring towards the 'warmer" part of the Castelli temperature spectrum. If you want something for rides for when its 5°C to 10°C outside, then consider choosing an item that's classed for use in the 10° to 15°C range especially if you are riding hard – you can always add a thicker base layer or a light shell to build warmth if required. Wear a jacket that's too warm and you're instantly out of options.

Choose your kit with the aim of being just-warm-enough for the intensity you're riding at. If you start sweating you, will get damp and this will make your colder. We've gone into more detail on this in our guide to waterproof and breathable jackets.

Cold feet? Please note warm winter socks squeezed into summer shoes will restrict blood flow making your feet colder, that and your summer shoes are designed to be vented. So consider buying a half size bigger cheaper shoe for your winter riding, so you can fit a warmer sock inside and then use a lighter more breathable shoe cover if its cold & dry, and only use waterproof shoe covers in the wet otherwise your likely to get sweaty feet which will then chill airflow and moisture managment are big issues for temperature control.

Always consider layering - you need to wear a wicking base layer next to your skin - you could have a £300 jacket and wear a cotton t-shirt under it and you will be cold and clammy and always take a lightweight shell with you – it's amazing what 100 g of polyester can do to keep you warm. And remember if your getting a bit hot remove your gloves and just undo your collar a little instead of keeping your gloves on and unzipping your jacket to the naval - this will help regulate your temp without getting a chill on your chest.

Castelli do however produce several winter pieces with built in layers that allow you to adjust the warmth and airflow mid-ride, while still protecting your core- ideal for changeable conditions and altitudes without the need to remove and store clothing. Check out the Alpha RoS Jackets and Jerseys for both men and women

Finally if in doubt, send us an email or get in contact on Twitter with a few details about the riding you do, your build and what you're looking for and we'll do our best to help direct you to the best solution(s) for your needs.