Tag: physiology

Physics doesn’t change. Only our understanding of the principles does. Given how long ago I wrote this article, it has not just stood up well to the passage of years, I’d venture to say that it was is quietly ahead of its time, at least in the world of motorcycling: the emphasis on core temperature, cognition and risk perception, and decision-making, rather than just comfort, aligns very closely with how cold-weather risk is framed today in both occupational safety and human-factors research. Hypothermia is insidious and often unrecognised and framing getting cold as a decision-making and control problem is crucial, and extends far beyond a comfort issue, something still under-emphasised in mainstream motorcycling advice. That reinforces why riders underestimate cold-related risk. The central insight — cold hands are a symptom of falling core temperature — is the core of the article and scientifically valid as is the explanation of insulation as rate-of-loss reduction rather than heat retention. This is a mistake riders still make even today, relying on layering too much.

Where I writing the article today, I would point out that much of my critique of heated grips is fair, but they are more reliable and somewhat more effective than the ones I struggled with back in my courier days, but they are still more useful as a supplement to heated clothing, but not a solution, particularly on a long ride.

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Staying Warm on two wheels

Motorcycles and cold weather aren’t entirely compatible. Whilst the biggest winter risk to riding in the UK is ice, the subtle disorientation caused by hypothermia isn’t that far behind. The wind chill factor is considerable on a bike, and the hands are stuck out in the wind. They also have a large surface area to lose heat from, and so are the first part of the body that we notice getting cold. Unfortunately, because gloves still need to allow us to operate the controls, they are also probably the most difficult part of the body to keep warm. Over the years, I tried all sorts of ways of keeping my hands warm. I tried some pretty expensive kit as well as ideas I knocked up myself for nothing. So have a read, learn from my experience, and before you dash out and spend big cash too, don’t make the same mistakes I did.

In an attempt to keep my hands warm I’ve tried:-

thick gloves
thermal gloves
World War 2 flying gloves (really!)
skiing gloves
silk inner gloves
thermal inners
overmitts
handlebar muffs
cut down milk containers
heated inners
heated handlebar grips

But before I discuss how well they worked – or didn’t work – let’s consider just why hypothermia isn’t uncommon when riding a bike.

Heat is lost from the body by three routes:

radiation
convection
conduction

Fairly obviously, the blood flows out down our arms and legs to hands and feet, and back to the heart. But when it’s cold, the blood passing down arms and legs is cooled by the windblast – their large surfaces act as radiators – and returned to the core of the body. Now it has to be re-heated before being pumped round the body again. The body can cope with mild cooling – it just turns up the heat by burning more fuel – but there’s a limit. Once we start losing heat faster than the body’s self-warming process can cope with, we start losing heat from the body’s core. And the steeper the temperature gradient (ie, how cold it is), the faster we chill.

Now, we don’t really feel any of that, but what we feel is the next stage. As our core temperature starts to fall, the circulation of warm blood to the surface capillaries begins to shut down to reduce further heat loss. Skin feels cold to the touch. Go a stage further and the blood supply to the body’s extremities also starts to shut down – now it’s not just skin that’s cold, but our hands and feet, and eventually even our arms and legs.

What are the effects of this chilling? When are arms and legs get cold, the muscles operating our fingers, hands and feet become stiff and unresponsive. And we start to struggle to control the bike. I remember one icy ride from London to Kent when I couldn’t actually change gear for the last ten minutes.

That’s bad enough, but it gets worse. We also lose heat through our neck and head, and that means the brain is affected too. We start losing focus and making bad decisions.

So that’s hypothermia. And it sets in surprisingly easily on a bike. If you’ve ever reached the stage of shivering uncontrollably, you’re in the early stages of hypothermia. . This is not idle speculation – this comes straight from sports physiology research.

So what was the mistake I made? It’s pretty obvious when you read the list above – they were all attempts to keep my hands warm. Unfortunately, that’s treating the SYMPTOMS rather than the DISEASE.

Let’s just recall what thermally-insulated clothing does. We think of it as ‘retaining’ heat, but that’s not actually how it works. It SLOWS DOWN the rate of heat loss.

So here are two points to think about:

thermal insulation only works up to the point where the temperature gradient across the insulation is steep enough for the rate of heat loss to exceed the body’s ability to heat itself. Once temperatures dip low enough, from that point on, we are going to chill. For clothing with good thermal insulation, that threshold temperature is lower.

if we only ride short distances, thermal insulation may slow down the rate of heat less enough that we don’t notice the chilling effect of cold weather. But on a longer ride in the same clothing, we will continue to lose heat for as long as we’re riding, and then all that our thermal clothing can do, no matter how good it is, is to delay the onset of chilling. It prolongs the agony, as it were. This is a serious problem if you are habitually a short distance rider and suddenly do a long trip. It took me years to understand why the clothing that kept me nice and warm on short rides let me get so cold on long runs.

So the key point is that whilst moderately chilly weather may be tolerable for short rides, as soon as the temperature really dips or we take a long ride, we’re going to chill. Circulation to the arms, legs and brain are all reduced, and eventually we’ll lose our mental focus too.

One obvious solution is to keep adding thermal insulation until we stay toasty. That’s the idea behind ‘layering’. But after a bit, thick gloves with inners get too bulky to be easy to use, and we end up looking like the Michelin Man – try looking over your shoulder!

So let’s step backwards a bit, and recall that if we keep the core temperture high, blood keeps circulating. But how can we supplement the body’s own ability to supply enough extra heat?

Well, the obvious solution if hands are cold is to use something to heat the hands – heated grips and gloves . But remember – this is the symptom, not the disease. They might make our fingers feel warm but they are very inefficient – most of the heat produced is lost again, either by conduction down the metal bars or radiation from the back of the glove. My experience is that I still got physically cold even if my fingers felt warm, probably because the warm fingers ‘fool’ the brain into opening up capillaries to blood flow, which then loses heat. And as a secondary problem, I’ve found heated grips and gloves fail very quickly because of the constant flexing. I generally reckoned on a year for heated grips before the wiring failed and one winter for the gloves, sometimes just a couple of months. It’s the heating elements that go in gloves and the feed wire on the throttle side with grips.

So can we heat the core directly? We can, by using heated clothing. A heated jacket or waistcoat adds heat where it’s needed, and given the same insulation, the result is that we push the point where we start to chill to a lower temperature. With core temperature maintained, so is circulation to the extremities and so hands and feet get a constant supply of warm blood.

In my experience of riding through really cold weather – I was a blood runner for several years, being called out at all hours of the night including in mid-winter – a heated waistcoat may not completely overcome the cooling effect but goes a long way towards it – on one 3am ride in January when it was -10c, my fingers still got cold but they didn’t go numb. I would have struggled to complete the ride without the waistcoat. I’ve found that if it’s chilly (10 – 5C) wearing a long-sleeved shirt, a light fleece then my heated waistcoat keeps me warm. If it’s cold (around 0) I wear the fleece over the waistcoatr. Below zero, I put unlined waterproofs over my riding suit, and that is sufficient to deal with a three hour riding down to about -10C.

Heated waistcoats are available for around £100 and my experience is also that they last much longer. My first Gerbing waistcoat lasted a decade, and my replacement from Exo2 is even older. Only the oldest bikes will have problems with a waistcoat – they draw no more than about 30 watts – half a halogen headlight bulb. It’s also possible to daisy-chain heated gloves, socks, leggings and collars from some manufacturers, but make sure your bike’s alternator can cope with all that lot.

Personally, I’d avoid a heated jacket. You can wear a heated waistcoat under several layers of insulation BEFORE putting a jacket on – you can’t do this if the heating element is built in to the jacket.

Final tip – plug the leaks! Keep wind out of your clothing by tightening wrist straps, using a scarf or neckwarmer and zipping jackets to trousers or wearing one-piece suits. Several thin layers are better than one thick one, unless it is a fleece – the idea is to trap air and stop it moving. If you have a separate jacket, bib-and-brace type trousers help keep the kidneys warm. A cheap one piece rain suit over the top will do wonders if you have separate jacket and jeans.

And a word of warning – don’t put the heated waistcoat next to the skin – the heating element can get pretty hot and you will end up looking like you barbecued yourself! You can get inline temperture controllers, or just wire in a simple on-off switch on the bike’s dash. Don’t forget to fit an inline fuse to avoid self-immolation.

If you want to stay warm on a bike this winter, spend some smart money on a heated waistcoat!