CyclistShould you still wear a base layer in the summer?Youve seen it on mountain stages of the Giro dItalia, Tour de France and Vuelta a Espana. As the sun beats down and riders push themselves to their physical limits, they unzip their jerseys.Some reveal an emaciated bare chest; others show off a base layer beneath the jersey.But whos got it right?When it comes to the question of whether you should wear a base layer under your jersey when the mercury rises, we couldnt even reach an agreement in the Cyclist office, so we decided we needed to investigate the pros and cons more closely.Logic would suggest that more layers will simply make you hotter in the sunshine, but many will insist that abase layer will actually keep youcooler in the heat. Related Posts Best energy drinks for cycling: Electrolyte and carb mix buyers guide Best cycling socks for summer: Top picks and how to choose Best cycling shoes 2024 How does hot weather affect your cycling performance? What is the point of a cycling base layer?The layer of clothing directly in contact with your skin helps your bodys natural defences against overheating. Fabrics must facilitate homeostasis (heat regulation) with adequate moisture management during exercise in hot conditions.While its generally accepted that layered clothing is best to manage your bodys thermoregulation when its cold, opinion is divided over whether a base layer should be worn when its warm.The type and structure of a base layer needs to change in summer, but the principle remains the same, says Graeme Raeburn, lead designer for clothing manufacturer Rapha.Sweat accumulating on your skin needs to be removed by wicking to help keep you comfortable and regulate your body temperature.Id recommend wearing a base layer in all weathers. Its just a question of choosing the right one for the conditions.Jersey fabrics might be required to do lots of things look aesthetically pleasing, be aero, take a sublimation print or embroidery, be dyed to a particular colour and so on all of which can affect their functionality, but a dedicated next-to-skin layer enables the fabric to target just one thing: wicking sweat, and therefore taking heat away from the body to keep the wearer cool and dry.So apurpose-designed summer base layer can be more effective at moving sweat and taking away body heat [than just a jersey] because the structure can have a much bigger surface area for the sweat to evaporate from than bare skin or a more closed jersey fabric.Omar Visentin, director of R&D at high-end Swiss brand Assos, seems to share Raeburns views.In theory, sweat transfer away from the body could be done directly by the outside layer the jersey but it is important to realise that this task translates into complex technical requirements for a garment, so a highly specialised textile the base layer can have a competitive advantage over a generalist garment such as a jersey, which also has other requirements to fulfil.That said, there is obviously also room for specific circumstances and personal preferences. Different cyclists might choose different approaches, but I would say that as a general rule the use of a base layer is justified even in hot conditions.Should you wear a base layer in summer?Given what weve just learned it would seem a base layer would be a good idea year-round. However, not everyone agrees. Anyone who tells you to wear a base layer when its hot either a) doesnt ride a bike, b) is just trying to sell you base layers or c) is grossly misinformed. Actually, its probably a combination of all three, says Steve Smith, brand manager at Sportful.To understand when you should wear a base layer its good to take a quick look at the physics. When water evaporates, it cools. Its why your body perspires, so moisture on the skin evaporates and cools it down.In cooler temperatures, if that evaporation happens on the skin surface you get cold from the evaporation but also from the conductive cooling of the liquids remaining on the skin if the moisture doesnt evaporate fast enough.Thats why you feel cold in the winter if youre wet under a jacket and why a 22C swimming pool feels cold but 22C air temperature feels comfortable.So for cold or moderate temperatures, the goal of a base layer is to keep you dry by moving the moisture away from the skin.When we get to warmer temperatures the goal is to actively cool the body.To do this we need to encourage the evaporative cooling and move it as close as possible to the skin. Hence no base layer. We see a lot of pros get this wrong, but it seems like theyre learning now.Smiths argument for ditching the base layer assumes the jersey youre wearing is itself capable of correctly managing the moisture transition to evaporation.Of course, Sportful produces a garment designed for this, so as not to start any inter-company squabbling, we looked to an impartial expert.Do base layers keep you cool when cycling in summer?Enter Dr Mark Turner of the Performance Clothing Research Group, University of Leeds. He would seem to agree more with Smith than Raeburn and Visentin, although his answer may also surprise you.When we asked him whether hed wear a base layer under his jersey on a hot day his response was, No, Id just wear the base layer.In a roundabout way this concurs with Smiths ideal of a single, breathable, wicking layer working best, although it may also conjure up some alarming mental images of cyclists in string vests.Turner goes on to say, Thats not obviously realistic, more an ideal world scenario. The reality is there are so many other factors to consider with cycling, such as aerodynamics.I read that an open knit style [string vest] base layer worn under tight fitting Lycra creates a more aero surface texture [like a golf ball].Im not sure if that was ever substantiated, but it goes to show its not always just about wicking, especially where pros are involved.If a jersey is made in the right way, and has its own wicking properties, I see no reason to wear a base layer. But human physiology is unpredictable and were not all alike.Everyone sweats at different rates so theres no hard and fast rule for what will work for you.That being the case, we decided to widen the net.By his own admission, Simon Baynes of sportswear manufacturer Craft is sitting on the fence on this one. In his opinion its entirely dependent on the jersey material.We make a jersey based on the properties of our Cool Mesh Superlight base layer, so when the jersey is constructed in this way its not necessary to wear an additional wicking layer.However he goes on to say, This is a specific case, and I would generally always advise heat management begins with functional underwear be it summer or winter.What is the best base layer for cycling in summer?Liam Steinbeck makes his living studying fabrics as a material sourcing specialist for Gore Bike Wear.His opinion is that there is no physiological benefit to wearing a base layer but, like Turner, Steinbeck is clear about one thing wicking is not the only factor: Even if a garment is engineered for moisture management, if there are poorly placed seams or labels it can be equally negative for the wearer.People wear base layers for different reasons some for comfort, while some believe it helps in a crash.Raphas Raeburn also raises the comfort issue, saying, A base layer can be designed with comfort as the priority, so lighter, softer fabrics can be chosen, flat-locked seams used, and labels placed on the outside. Plus layering bibs over a base layer will be more comfortable.Andy Storey of cycle clothing retailer Prendas Ciclismo considers another aspect of base layer selection the right cut.People often ask why they should buy the vest version [of a base layer] when they already have the regular T-shirt shape.Limiting the material on the shoulders actually gives a great cooling effect [think about the cycling position] without compromising the extra protection on your chest.Storey goes on to say, I always wear a base layer in the UK because the temperature rarely gets over 30C and when used with a full zip jersey I feel this is the most effective combination.Castellis senior UK brand manager, Rich Mardle, is also a big believer in the base layer, recounting his experiences riding in South Africa in 40C+ heat: I found that when I rode without a base layer I felt hotter, especially with hot patches over the shoulders where a jersey alone seemed to retain heat.There was noticeably more salt build-up and the comfort wasnt great. After that I would, and will, always ride with a base layer.He does concede, however, that his African adventure was a few years ago and jerseys are now lighter and much more technical.So the final answer is well, there is no final answer. As always, its not as simple as right and wrong, and its worth experimenting to find what suits you.Keeping cool, with or without a base layer, will depend on your jerseys wicking qualities, your comfort preferences and your performance goals.But most importantly, it will depend on whether you like to rock the Rab C Nesbitt look.Fit for purpose: Tips on buying a baseRegardless of how technically advanced a base layer is (or how persuasive the salesperson), dont buy one until youve tried it on.It can only function properly if it fits you correctly. By that we mean you need to ditch your sartorial concerns and go skintight its not like anyone is going to see it anyway.The fabric should hug your every curve without being restrictive to your movements and breathing. Its important to have as much surface area as possible in contact with your body in order for the material to do its job of transporting moisture away from your skin and allowing the evaporative process to function efficiently.Baggy material will not do its job well and will also tend to bunch up under bib shorts and jerseys, adding to your discomfort instead of making you more comfortable, which is the objective.The cut you decide on short-sleeved or sleeveless is largely amatter of personal preference, but watch out for tightness under the armpits which can occur with T-shirt style base layers when you assume the cycling position, especially if you are using a snug-fitting jersey too.Want to keep your feet comfy this summer too? Read our guide to the best summer cycling shoes Related Posts Best energy drinks for cycling: Electrolyte and carb mix buyers guide Best cycling socks for summer: Top picks and how to choose Best cycling shoes 2024 How does hot weather affect your cycling performance? The post Should you still wear a base layer in the summer? appeared first on Cyclist.