If you generally average around 25mph (40kph) for a 10-mile TT, switching to pair of aero socks isn’t going to have you suddenly going sub 20:00. But although the gains are squarely in the ‘marginal’ category, they do all add up.

It has been shown by wind tunnel testing that particular fabrics are more aerodynamic than just bare skin. Looking around at the full TT garb of the pros, such an abundance of long sleeves and socks certainly do serve to corroborate this.

Naturally, there is an arms race for who can provide the greatest gains. Designed in collaboration with Aerocoach, wind tunnel testing shows these socks providing a 5.3w saving over bare legs at 45kph – which would equate to being 9 seconds faster over a 10-mile TT. The testing also showed the Flow-socks as being 2.2w faster than generic aero socks with 1mm deep stripes running vertically.

Of course, I don’t have the facilities to verify these claims, and so won’t be able to comment on just how effective these socks really are. Differences of this level are essentially imperceptible in just general riding. So, the focus here is going to be on the comfort, breathability and how they feel in use.

But just before we leave the discussion of aerodynamics behind, it’s worth noting that Alex Dowsett was wearing a set of socks which look very similar to the Flow-socks when he won Stage 8 of the 2020 Giro d’Italia from the breakaway.

Nopinz isn’t an official sponsor of Israel Start-Up Nation, so naturally this isn’t something that can be confirmed. But as six-time national champ in the ITT, Dowsett does have a reputation for optimising his setup, and his choice of equipment does speak volumes.

The construction: Nopinz Flow-socks

The Flow-socks have a breathable lower portion, constructed from the same kind of lightweight fabrics as you get on a typical summer cycling sock. Around the ankle, there’s a seam where the lower portion of the sock meets the aerodynamically optimised fabrics – which go on to extend around 19cm up the leg.

There are two fabrics used on the upper portion, with Nopinz's Speedscalez fabric at the front being a bit thicker than the Pista fabric used on the sides/rear. The design is fully UCI compliant, so you shouldn’t have to worry about them being too long or having ribs greater than 1mm.

These Speedscalez and Pista fabrics are quite compressive, but to further ensure that the socks won’t slip down, there is a silicone gripper at the top to hold everything in place.

The ride

The lower portion of the Nopinz Flow-socks did prove to be highly breathable, as lightweight and quick wicking as you would expect from a summer sock. Both in the blazing sun and in the humidity of tree-lined lanes, my feet stayed at a manageable temperature within my shoes.

Moving up the socks, I found the seam around the ankle, connecting the breathable lower to the aero upper portion of the sock to feel a little rough against my skin. This isn’t a necessary evil of this style of sock, the Castelli Fast Feet aero socks manage the transition without a problem. 

But that said, the sensation isn’t a deal breaker with these socks – although the join can be felt, it hasn’t caused any visible marks on my skin, even on rides nudging four hours in length. So no actual physical problems, even if it doesn’t feel quite as nice.

The Speedscalez front panel of the upper portion of the sock isn’t very permeable, you feel a little isolated from the wind by it – more so than other aero socks. But the thinner Pista rear/side panels did their job heat management-wise and I didn’t feel like I was overheating.

Together, the Speedscalez and Pista fabrics are quite tight; putting the socks on does take a bit of leverage. But once pulled up, they’re definitely not overly tight, the feeling is one of pleasant compression. I had zero issues with them slipping down – they could probably stand up even without the silicone gripper, but with that they stayed rock solidly in place.  

Value and conclusion

At £28.99 the Nopinz Flow-socks are quite reasonably priced. They are significantly cheaper than Castelli’s Fast Feet aero socks, which come in at £36, although more expensive than Condor’s Aero Socks at £24.99.

Price per watt saved over bare legs would be the best metric to measure value by, but unfortunately we don’t have back-to-back testing data to hand. 

In all, Nopinz’ Flow-socks are a breathable and gently compressive set of socks which have aerodynamic credentials backed up by Aerocoach and some of those in the pro peloton. The ankle seam is a little rough against the skin, but doesn’t present an impediment when speed is the absolute focus.

Castelli's fast feet aero cycling socks are constructed with “engineered grooved Lycra to help detach airflow,” with the intention of improving aerodynamics for faster riding.

The gains fall very much into the “marginal” end of the spectrum, slipping these on won't have you suddenly dropping your mates on the flat. But if you've got a little bit of cash to spare, it certainly can't hurt - and there has been a fairly wide take up of this style of sock by the pro peloton, especially in TTs.

The construction: Castelli Fast Feet aero socks

The lower portion of the sock is based on Castelli's time-proven Rosso Corsa, with the aim to provide comfortable coverage and good ventilation. Around the ankle, the make-up changes to that distinctive grooved Lycra, which has a feel similar to a jersey or set of bib shorts.

There's a large focus on breathability, with Castelli recommending using these socks when the conditions are too warm for their aero shoe covers – which have the same grooved profile on the legs and also smooth out the surface of the shoes, causing lesser disruption to the airflow.

The socks extend 18cm above the center of my ankle joint. This is longer than I would typically go for in a sock, but in this case I'd say it's a good thing – you’re paying a premium for grooved Lycra, so it wouldn't do to skimp on that. On the inside of the cuff there's a silicon gripper to keep the socks in place and to prevent them from falling down.

Something to note about the silicon gripper is that it can pick up fluff from other clothes. Pulling this off isn't exactly arduous, but it's not something you'd particularly want to spend your time doing. However, I found this was easily solved by making sure to turn the sock you're folding it with inside out, so the silicon gripper is kept on the inside and not brushing up against any other fabrics.

The ride

the Fast Feet socks lived up well to their billing as aero optimization for hot conditions. Wearing these for Zwift races, the lower portion of the sock did an excellent job of quickly wicking away sweat and allowing my feet to breath. While they did end up a little damp by the end, there was at least no feeling of clamminess.

Even on long Sunday rides, the lower portion of the sock never felt uncomfortable inside my shoes, with no awkward seams causing hotspots or irritations.

The upper portion of the socks wasn't quite as breathable as the lower, so those seeking the maximum in ventilation would be better served by a different sock. But my lower legs don't tend to get as hot as my feet, so this never caused me to feel uncomfortable. It would have to be outrageously warm before getting to the point that I'd feel that the Lycra portion is too hot.

The silicon gripper did a great job at keeping the socks at the right height and they never once slipped down. However, I did find that after wearing them continuously for over six hours that the gripper did start to cut into my skin, leaving a little mark on the inside of my left leg that took a few days to fade away.

It's not too much of a criticism though, as the majority of their application will be in shorter efforts. Plus generally, if a ride is over six hours and yet demands the application of aero socks, there's probably going to be enough other discomfort in the name of aero that a little bit of digging in from a cuff would be pretty low on the list of concerns.

Value

As aero socks go, the Castelli Fast Feet are on the pricier side at £36. Huub’s Aero Socks, Conder’s Aero Socks and Nopinz’ Flow-Sock each come in at £30, £24.99 and £28.99, respectively.

But having not yet tested those three, we can’t comment on how they compare for comfort – other than the gripper cutting in after six hours, the Castelli socks were an utter pleasure to wear.

The Castelli Gregge 15, with its middle-of-the-road 15cm cuff and 50 per cent merino content, is a more versatile sock, intended for a broader range of conditions and riding styles than a dedicated winter item. If it's maxed-out warmth you’re after, you’d be better off with Castelli’s Primaloft socks.

The qualities of merino wool make it ideally suited for cycling socks in colder climes. In being naturally antibacterial, your feet stand to be fresher after a ride, while the thermal properties – which remain to a surprising degree, even when wet – promise to keep your toes toasty.

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Castelli Gregge 15 socks: construction

There are some brands that talk up the wonderful qualities of merino wool, but then include so little in the fabric that it’s hard to believe any of the benefits are being conferred at all. Some blending of materials is still needed to make the sock stretchy and hard wearing enough, so there’s no need to look for 100 per cent merino socks.

With that out of the way, the 50 per cent merino content, combined with 25 per cent elastane and 25 per cent polyamide, looks to be a reasonable balance. Although, lower than what you would get in the dhb sock or the Endura sock , at 65 and 74 per cent, respectively.

The Gregge 15 socks have a significantly lower profile than some of their competitors, which makes them easy to fit into summer shoes. That said, these are still intended for cooler rides, they’re not a summer merino sock.

The ride

Pairing them with a set of summer shoes for dry rides at around 12°C, my feet didn’t feel any pangs of cold. And thanks to the low bulk of the socks, the feel inside my shoes was much the same as with a more summery item – a stark contrast to cumbersome winter warmers. On longer riders they remained comfortable, with no seams causing any hotspots or pains.

Five degrees colder and in heavy rain, although slightly damp, my feet remained quite warm. Admittedly, I was wearing overshoes when out in these conditions, but these socks don’t claim to be miracle workers – I’d have paired a set of overshoes with any sock in that weather.

Value

The Castelli Gregge 15 socks are cheaper than the £22 Cadence DNC Merino Wool socks, which offer a similar combination of low-profile and warmth. Although dhb’s Aeron Mid Weight Merino Sock does undercut Castelli, coming in at £12, the dhb socks are noticeably bulkier – the difference in price is matched by a difference in performance.

In all, the Castelli Gregge 15 socks are pricier than your standard sock but are actually pretty good value for their low-profile merino construction.

Sealskinz is a British brand that has been battling the elements for the past 25 years with a wide range of waterproof clothing. Socks present a somewhat unique challenge; not only does a balance have to be struck between water resistance and breathability, but also something has to be done to stop the water getting in from the top and pooling around your toes.

These cycling socks do a commendable job at a challenging task, but unfortunately, they are not entirely effective.

The construction

To provide waterproof properties—without making you feel like you’ve just popped some plastic bags on your feet—Sealskinz has utilised a three-layer construction in these socks.

The outer layer is a nylon-elastane blend that is said to provide the sock with durability. The middle layer is a hyrdophilic membrane that’s naturally waterproof, so it won’t need reproofing and shouldn’t degrade in washes. The inner layer is a merino blend, intended to feel comfortable against your skin and provide a little warmth.

A silicon gripper—similar to what you’ll find on the hem of many cycling jerseys—is designed to keep the sock snuggly sealed against your leg and to prevent any water coming in from the top.

The neon yellow highlights of the sock are a welcome inclusion for increasing visibility—a particular benefit as these socks will mostly be used in foul weather. That said, very often they will be hidden under bib tights or legwarmers, which somewhat mutes the effect. But if you prefer a stealthier look, they are also available in grey.

The fit

Although Sealskinz makes bold claims that these socks are supposed to feel like any normal sock, this really wasn’t my experience.

The socks really aren’t very stretchy at all, so getting the sizing spot on is important or you will end up with too baggy a sock or too tight. Fortunately, Sealskinz’s size guide seems pretty well calibrated and the recommended size large fitted the length and width of my feet well.

However, the cuffs were a little large for my ankles, leaving a visible gap. Given how water coming in from the top is one of the biggest issues for a waterproof sock, this was not exactly encouraging. Admittedly I do have fairly slim ankles, but they aren’t that much smaller than average, so definitely something to be aware of if you sit on that end of the scale.

On the other hand, the height of the cuff is pretty spot on for my personal aesthetics. However, going for the longer length version could be a better decision for reducing the chance of water coming in from the top.

Despite the inner layer of the socks being a merino blend, putting on the socks still leaves you with that crinkly sensation reminiscent of a plastic bag. It’s not a deal braker, but it certainly is not akin to wearing a normal sock. The silicon gripper in the cuff felt fine against my skin and was unnoticeable while riding.

In terms of bulk, these take up significantly more volume than a standard pair of winter cycling socks, being most comparable to a set of old fashioned hiking socks. If your cycling shoes are already on the tight side, there is a fair chance you wouldn’t be able to fit your feet in them while wearing these socks.

The ride

When out riding in the pouring rain, my feet did get wet. This shouldn’t have been down to the gappy ankle letting the water run down, as I was wearing some wet weather legwarmers over the top, creating a kind of labyrinth seal. I would put it down to the outer material soaking up the water and by some form of capillary action, water getting through the membrane. But however the water got in, it pooled around my toes and created a kind of chilly bath.

On the bright side, I very much appreciated the windproof qualities of the sock, which enabled me to wear my summer shoes on cooler days than I would otherwise be able to get away with. They also did a good job at keeping my feet dry from road spray on mornings when overnight rain had left the roads slick with water.

Sealskinz claim that the socks are built for comfort and blister protection and, although they may be bulky and feel a little different to normal socks, I didn’t suffer from any hotspots or blisters—even on rides nudging four hours.

Breathability has been somewhat sacrificed in these socks. Going out on a cool—but dry—day, my feet were left quite clammy by the end of the ride.

Value

At £32.50 these are boarding on the price of a set of overshoes. For example, the Dexshell Heavy Duty overshoes are £35 and impressed us enough to gain a 10/10 on test.

If the goal is keeping your feet warm and dry in deluge, these socks don’t compare particularly favourably with overshoes. If you're after extra protection from light rain or road spray, they're a solid choice - though overshoes could meet both needs.

You might have seen your fellow cyclists wearing flamboyantly coloured hosiery. If so, there is a good chance that they were a pair of Sako7 socks.

Sako7 is a range of socks and cycling apparel created by South African Sean Sakinofsky. Sakinofsky came up with the company's name by combining his nickname with his lucky number. Matching its distinctive name, Sako7 has a reputation for making bold garments.

Sako7 says that its designs are influenced by Sakinofsky's life experiences, famous artists, along with individuals or movies that have influenced his life. Further Sako7's other cycling apparel lines are said to be strongly influenced by its range of socks.

With the combination of primary colours the Mondrian White socks are definitely eye-catching, but they also look good with most clothing combinations. The colour and style is said to pay tribute to the highly successful 1980s La Vie Claire Professional Cycling Team which included the great Tour de France riders Greg Lemond and Bernard Hinault.

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Having worn the socks on a number of rides I can confirm they performed well. The best compliment I can pay them is that when riding in the heat or in cooler temperatures my feet felt comfortable without any pinch points or irritation.

In short the Mondrian White socks ticked all of my cycling sock pre-requisites: six inch cuff length, distinctive appearance, well ventilated and they have not fallen apart after several rides. The only small criticism is that the cuff slipped slightly, but this could be due to my narrow ankles.

The GripGrab Thin Merino Wool socks form part of the brand's winter offering but got their first use on a chilly spring morning and have continued to be used late into spring.

The socks were suitably warm for the cold start and thankfully did not overheat as the day got warmer, thanks to the open mesh zones and the natural breathability of merino wool. It is these features that have meant they remain a comfortable choice with summer round the corner, and barring a heatwave they will probably be fine all the way through the warmer months.

On colder rides, these socks would be comfortable down towards freezing, but may leave your toes a bit cold on the most bitter of winter training rides due to the thin construction.

They are also a great fit — well thought-out compatibility across the brand’s range means the socks are the perfect height to remain hidden when wearing GripGrab overshoes.

As ‘winter’ socks, it is probably expected that they will be kept out of sight, which explains why they’re only available in dark colours.

We recently reviewed the dhb ASV roubaix bib shorts and were hugely impressed. These are the matching socks that can be worn to complete the outfit and when paired with the rest of the ASV range they look resplendent.

In our recent winter clothing guide we suggested these socks and have been wearing them since then. They have continued to impress us and when paired with neoprene overshoes our feet have remained warm and snug on the coldest days.

Being the same standard as that worn by the Wiggle Honda Pro Team, these socks are very comfortable, with well thought out ergonomics, that include flat toe seams and a reinforced heel for added comfort.

We had the pleasure of wearing these socks on a couple of biblically wet rides in South Wales during a severe weather warning. In such conditions our feet became wet (despited wearing overshoes), but remained warm thanks to the natural qualities of Merino wool, which retains a high level of heat even when wet.

You can easily pay twice the price to get socks of the same standard from other brands, with this pair further cementing dhb's reputation for quality and value.

For more information head over to Wiggle.

If you've decided that high-vis is en vogue this season, then these new dhb Flashlight socks are most definitely for you. Luminous yellow with nice reflective touches, they will add a bit of colour to your outfit during the day and make sure that you're seen after dark, although their breathability means they're best saved till spring.

Literally the most eye-catching feature of the dhb Flashlight socks is their colour. Luminous yellow might not be to everyone's taste, but with the likes of the SealSkinz Ultra Grip Hi Vis Gloves brightening up the roads, it's certainly here to stay. Setting these socks apart from other high-vis offerings from the brands such as DeFeet are the two 3M Scotchlite reflective bands which sit around the top and bottom of the cuff. Almost unnoticeable in daylight, once they sun goes down they turn into a rotating glimmer of light that should catch the eye of inattentive drivers.

The dhb Flashlight socks have a multipanel contruction which allows for a reinforced heel that proved comfortable and didn't show any sign of wear and tear over the period of our testing. The stitching around the toe was also of good quality with no portruding loose threads to tickle your toes and steadily drive you up the wall on longer rides.

The upper is formed of a dense mesh which extends from the toe to the bottom of the cuff, providing excellent breatability. However the dhb Flashlight socks are essentially designed for the morning and evening commute, meaning good breathability can equal slightly chilly feet for much of the year.

If you're after high-vis socks then these are some of the cheapest on the market at an RRP of £7.99, and dhb have done a good job of packing a pretty simple garment with plenty of neat features rather than just taking a standard sock and turning the lurid up to 11. We'll leave it up to you to decide where the dhb Flashlight socks will fit into your wardrobe.