Warm and stretchy skullcap that does a straightforward job very well
Castelli Viva Thermo Skully
8 10

Castelli’s skullcap is warm and stretchy and it’s slimline enough to fit comfortably under your bike helmet.

Let’s be honest, skullcaps never look great. They’re like overshoes in that they’re ugly as sin but they do the job. File them under ‘necessary evil’. Castelli’s Viva Thermo Skully actually looks okay, though, in our humble opinion. Worn under a helmet, it’s acceptable, we’d say.

More to the point, the Viva keeps your head – including your ears – nice and warm. It’s made from a Thermoflex fabric – a polyester/elastane blend – with a brushed inner surface that provides a surprising amount of insulation. The different panels are flat-locked stitched together so you can’t feel the seams, and the raw cut edge means there’s no discomfort there when you wear a helmet over the top.

I used this loads in that arctic spell over Christmas and it made a huge difference to my warmth – not just to how warm my head felt, but to how warm I felt generally. You sometimes don’t realise just how much heat you’re losing through your head. I’d start to get cold on a ride and think about heading home – then sling the Viva on and decide to stay out a bit longer.

I’ve used many skullcaps before, including windproof ones that I’ve always found too sweaty. This one isn’t windproof but it is highly breathable and it really does make a big difference when the mercury is low. It's very comfy and takes up virtually no space if you stow it in a pocket just in case.

The Viva is also available as just a 10cm-wide headband (£14) if you just want to keep your ears toastie in milder weather.


Warm and stretchy skullcap that fits under a helmet comfortably; does a straightforward job very well

road.cc test report

Make and model: Castelli Viva Thermo Skully

Size tested: One size, red

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Castelli say: "Thermoflex is warm, soft and stretchy

Raw cut edge lies flat and doesn’t bunch under helmet"

Rate the product for quality of construction:
Rate the product for performance:
Rate the product for durability:
Rate the product for comfort, if applicable:
Rate the product for value:

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Overall rating: 8/10

About the tester

Age: 40  Height: 190cm  Weight: 74kg

I usually ride:   My best bike is:

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: time trialling, commuting, sportives, general fitness riding,

Mat has worked for loads of bike magazines over the past 20 years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for seven years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a youthful 45-year-old Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.