The cold, as even a modest winter training ride will demonstrate, is not to be taken lightly; it was for good reason that Dante placed the circles of ice below those of fire in his Inferno. “Human beings are homeotherms,” explains Dr Christopher Davis, Medical Director for altitude and mountain medicine at the University of Colorado, and whose department studies the effects of extreme conditions on human performance. “We want our body temperature to be at 37C.”
As warm-blooded mammals, we’re losing heat constantly and need to burn calories to keep our fires stoked. It’s surprising how delicate this internal thermostat is: if our body temperature drops below 35C we’re on the verge of mild hypothermia, manifested in a general clumsiness, impaired judgement, slower reaction times and a certain argumentativeness. Simple activities such as zipping up a jacket, let alone changing an inner tube, become more difficult. We shiver violently because heat is a byproduct of muscle activity. But with a core temperature below 32C we no longer have the fuel to shiver. Below 30C and consciousness ebbs away. By 20C – the temperature of a late-summer afternoon – the heart has stopped.
So, why is keeping our hands warm so important? “We rely on electrical impulses to send signals to and from our brains,” says Dr Davis. The hand is a hotbed of nerve activity, befitting such a complex piece of engineering and at a temperature below 20C those impulses are inhibited. The 30 muscles in our hands prefer to operate at above 28C, while the synovial fluid around the hand’s 30 or so joints acts like lubrication in a car engine – it’s sluggish when cold. And there’s an interesting third factor, notes Dr Davis: the pain of cold hands distracts you from the task of achieving your goal, which for cyclists translates as a psychological hindrance on overall riding performance.
Hands get cold because we have evolved a life-over-limb survival strategy: when air temperatures fall, blood vessels in the body’s extremities (the hands, the feet, the ears and nose) constrict, keeping warm blood away from the surface of the skin where body heat will be lost through conduction. But it’s a balancing act – to stop skin freezing it has to be supplied with blood, so when the temperature of the hands falls below 10C capillaries suddenly reopen in a warm rush, then continue opening and closing to manage the core body temperature against the loss of feeling in the fingers. With a high surface area, a low volume and lots of blood vessels close to the surface, our hands are especially susceptible to heat loss.
Our worst enemy, however, isn’t just the cold and the air temperature doesn’t have to be below 0C for trouble to strike. The crucial relationship is between the cold, the wind, the effects of which are more pronounced when riding, and being wet. Graeme Raeburn is the designer behind the Rapha Winter Glove System, which comprises the Winter Glove, the Deep Winter Glove, a Merino Liner and Overmitt. “There’s more than one type of cooling,” he explains. “Even in non-freezing conditions, moisture – whether that’s rain or sweat – combined with wind can mean experiencing greater heat loss than you would in cold but dry weather.” Bearing in mind that air temperatures typically fall by 1C for every 100m of ascent, cyclists in hilly country will want to protect their hands from the wind and the rain. Wind chill charts show that a temperature of 1C will feel like -5C in a 25mph breeze. Dr Davis concurs: “Wet hands are especially risky – water is a far more efficient conductor so the exchange of heat takes place fast [up to 25 times faster – which is why swimming in cold water is more dangerous than treading water].”
For mountaineers, Dr Davis advises shaking the hands out every now and then, getting rid of wet gloves and warming the hands in your (or someone else’s) armpits. Then put on the spare pair of gloves he recommends climbers carry. Cyclists don’t have the luxury of being able to carry several sets of winter gloves. Which is precisely why Graeme spent two years designing the Rapha Glove System. Given the variable conditions on long rides – warm valleys, cold summits, squalls of wind and rain – Graeme devised a versatile layering system which can be adapted depending on conditions. The Winter Glove uses breathable, lightweight resistance against wind, water and cold and can be supplemented with the Overmitt in very wet conditions. “The Deep Winter Glove,” Graeme explains, “is extremely technical, with sealed seams and a patented waterproofing technology. It’s insulated with PrimaLoft®, which is very fine and has a very low moisture absorbency. The body and shell is stretched nylon coated with a durable water repellent.”
A key objective of the Glove System was to retain the hands’ natural dexterity.
“A lot of work went into the fit and ergonomics, matching the curve of the hands on the handlebars,” says Graeme. The lining of the Deep Winter Glove is fully bonded to the outer glove, so there’s no shifting or slipping, and the fingertips feature a touch-screen-friendly finish for smartphones and GPS units. The result is that riders in wintry weather avoid having to take their gloves off and exposing their hands to the cold.