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Castelli Sfida 13 Women's Socks



Warm, breathable and exceptionally cosy – great for most winter days on the bike
Good length
Heel prone to bobbling

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The Castelli Sfida 13 Women's Socks offer exceptional comfort and insulation. They will serve you well through a wide range of winter temperatures, too, which goes a fair way to justify their expense.

The Sfida socks are like having a pair of cosy slippers on. They are, by far, the most luxurious winter socks I've worn. They don't offer any kind of compression and are quite thick, though, especially against something like Sportful's Wool Woman 16 socks.

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The thick terry footbed is what really sets the Sfidas apart. It does a super job of keeping your feet warm on even the coldest of days, and you really sense the cushioning under the foot. I've even used them without overshoes on cool, dry rides, something I rarely dare to do – I am one for overshoes as soon as the mercury drops into the low teens.

2021 Castelli Sfida 13 Sock Women 2.jpg

Sweaty feet weren't an issue when I added overshoes, or wore the Sfidas on milder days either. They're a good length, and the ankle area gets an extra layer of protection too.

The merino certainly helps keep odours at bay; I got several wears out of them before they made it into the machine. After that I noticed a very small amount of shrinkage – not enough to affect the fit, though.

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The're also showing signs of bobbling at the heel, particularly at the pattern edges. There's no visible thinning though, and the fabric still feels as soft against the foot as on day one. To be fair, I'm sure the bobbling has been aggravated by my off-road shoes, which have a more textured interior.

If the brilliant pink doesn't appeal, they're also available in black and celeste (for £1 less).


They're appropriately priced given that they can deal with a good range of winter temperatures. Those Sportful Wool Woman 16 Socks are £17 as well, and I don't think they offer the same comfort or temperature range as the Sfidas. The recently reviewed M20 Merino Crew Compression Socks are £16.99, and while they aren't female specific they do offer compression.

If you are on a budget, dhb's Aeron Light Weight Merino Sock is an option at £10, or they do Mid and Winter Weight versions for £12 and £15 respectively.

I'd say the performance and comfort of the Sfidas more than justify the price tag, though. You're sure to get plenty of use out of them, right through winter and, without doubt, will love the cosiness. The heel may start to look a bit worn early, but performance seems likely to stay high for a long time.


Warm, breathable and exceptionally cosy – great for most winter days on the bike test report

Make and model: Castelli Sfida 13 Women's Socks

Size tested: Large

Tell us what the product is for

The UK importer says: "The Castelli Sfida 13 Sock is a women's cycling sock designed for the cold. Super warm soft Merino wool is blended with Polyamide and Elastine to create a super snug fast drying and moisture wicking winter-weight cycling sock.

"The foot-bed of the sock is created using a Terry knit this creates a thicker than normal, luxuriously soft feel, but more importantly, it equals great insulation, where you need it most. The cuff extends to a generous 13 cm ensuring full coverage and more than enough sock to provide a decent overlap with your winter tights.

"Sfida translates as challenge dare or defiance, so make a stand defy the cold winter and go ride your bike."

Tell us some more about the technical aspects of the product?

Merino wool blend

Thick terry construction under foot for added warmth

13cm cuff

Rate the product for quality of construction:
Rate the product for performance:
Rate the product for durability:

See main body... wear is cosmetic and hasn't affected comfort or performance, yet.

Rate the product for fit:

No compression, but no bagginess or wrinkling for me with L/XL. I'm a 42 shoe.

Rate the product for sizing:
Rate the product for weight:
Rate the product for comfort:

The footbed makes the sock exceptionally comfortable.

Rate the product for value:

How easy is the product to care for? How did it respond to being washed?

Stick it in with the rest of the cycling kit at 30 degrees.

Tell us how the product performed overall when used for its designed purpose

Brilliant, really can't fault them – comfortable and warm without any sign of sweaty feet.

Tell us what you particularly liked about the product

Soft footbed – so cosy.

Tell us what you particularly disliked about the product

Bobbling and a worn look appear very quickly.

How does the price compare to that of similar products in the market, including ones recently tested on

Not overpriced given they do cater for all temperatures; most winter ones are around £15. Sportful's Women's Wool 13's are £17, as are M20's (not female specific), making Castelli's look a good investment. You can get cheaper with Madison's Isoler Deep Winter Socks (10.99) or options from dhb between £10 and £15.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your overall score

Very good performance and comfort – if they resisted cosmetic wear better, they'd be a nine.

Overall rating: 8/10

About the tester

Age: 39  Height: 173cm  Weight: 64kg

I usually ride: Road  My best bike is: Carbon road.

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: commuting, touring, club rides, general fitness riding, Getting to grips with off roading too!

Emma’s first encounters with a road bike were in between swimming and running. Soon after competing for GB in the World Age Group Triathlon Championships in Edmonton in 2001 she saw the light and decided to focus on cycling. 

After a couple of half decent UK road seasons racing for Leisure Lakes, she went out to Belgium to sample the racing there and spent two years with Lotto-Belisol Ladies team, racing alongside the likes of Sara Carrigan, Grace Verbeke, Rochelle Gilmore and Lizzie Deignan. Emma moved from Lotto-Belisol to Dutch team Redsun, then a new Belgian team of primarily developing riders, where there was less pressure, an opportunity to share her experience and help build a whole new team; a nice way to spend her final years of professional racing. 

Since retiring Emma has returned to teaching. When not coercing kids to do maths, she is invariably out on two wheels. In addition to the daily commute, Emma still enjoys getting out on her road bike and having her legs ripped off on the local club rides and chain gangs. She has also developed an addiction to touring, with destinations including Iceland, Georgia and Albania, to mention just a few. There have also been rare sightings of Emma off-road on a mountain bike…

Add new comment


nappe | 3 years ago

What makes a sock a woman specific sock?

Cycloid replied to nappe | 3 years ago

They Probably get washed more often

nappe replied to Cycloid | 3 years ago

May I present you with the "Reply Of The Day Award"

Cycloid replied to nappe | 3 years ago

Thanks -  Wit is not normally one of my strong points

It's not a flippant comment. I used to be a textile chemist in a previous life. one of the steps in garment testing is wash fasteness, The garment is subjected to a standard washing cycle and then assesed for Staining of white fabric and change of shade after the process.

A garment that is going to be washed more should have a higher wash fastness

I bet they are just the same as the men's though

Sriracha replied to Cycloid | 3 years ago

Um, yeah... shuda' quit whilst you were ahead there!  1

Cycloid replied to Sriracha | 3 years ago
1 like

You are probably right, I did not even get onto dimensional stability

Tass Whitby replied to Cycloid | 3 years ago

Or... sizing? Only two sizes in women's, three in men's for their big feet. Walking socks are often men and women-specific, too. On Bridgedale's website it says its women's socks are 'Specifically designed to fit the anatomy of the female foot, which is generally narrower, slimmer with higher arches...A sock that doesn’t fit correctly will have a baggy fit and this excess material will bunch inside boots and could cause unnecessary discomfort'.

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