How do cold temperatures affect a motorcycle rider, the motorcycle and ultimately motorcycle control or the interaction between the road and motorcycle?
Variations in temperature have significant effects on the 3 major components of motorcycle control, be those; the rider, the motorcycle or the road and they are all effected in varying degrees in different ways but at the same time.
The rider is affected by cold temperatures in two ways, either by ambient cold temperatures or cold wind temperatures which is really what a rider deals with when in motion.
With ambient cold temperatures the body loses heat at the skin and the body heat is transferred to the surrounding skin to air layer, which then acts as a minor insulation layer. The colder it is, the steeper the temperature gradient will be from the body temperature, thus the body will lose heat at a greater rate until ultimately the body does not have the energy reserves to keep the body ‘warm’ and it is at this point at which the ‘health of the body will rapidly spiral downwards into hypothermia. The way to maintain energy to produce body heat is to shelter, wear clothing and to eat & drink.
When the body is exposed to moving air or wind, the air that is heated by the body is quickly blown away and is replaced with the colder air, thus maintaining a steep temperature gradient which will make the body lose heat more quickly. This is essentially wind chill, where the wind is artificially maintaining the steep temperature gradient which causes the body to feel and be colder.
The cold causes the body to retreat and defend itself, by sacrificing the body extremities and preserving the central core. At first the body reduces blood flow to the furthest parts of the body, be those the hands and feet, hence why when riding the hands and feet are affected first in two ways; by the wind chill effect and by the reduced blood flow.
Any other exposed or poorly insulated parts of the body will also start to feel the effect and one of the first problems of the cold is how the rider ‘feels’ the controls. With cold there is a reduction in performance of nerves and muscles, hence sometimes when you have stopped riding and try to take your gloves off it becomes a tricky task as all your digits are numb and you end up taking them off by pulling at the gloves with your teeth.
If we relate this lack of sensation and lack of mobility to motorcycle control, then the colder the rider feels, the less sensation and mobility they will have, the less command of the motorcycle controls they will have.
It is this process by which many people who are progressively getting colder in exposed areas, may well suffer from varying degrees of frost bite.
Other early symptoms of the cold affects are ‘goose pimples’ which is where the hairs on the skin are moved to create a greater insulation layer. However this is legacy of early man and animals which have much more hair and functions much better. On the modern body it serves no purpose.
Shivering and trembling and chattering teeth are also another symptom of cold, whereby muscles and body tissues start to contract rapidly which initiates heat production.
Another well observed symptom of feeling cold is the desire to urinate as the body restricts blood flow to the extremities. The overall body blood volume decreases and the blood pressure increases and the body compensates by attempting to reduce the volume of fluid by causing water expulsion in urine.
The cold also has influence on the brain function and how it ultimately will affect the rider’s ability to control the motorcycle in a specific way for a given set of environmental conditions.
For the rider, as long as the ‘health of the body’ remains stable and the body does not lose too much heat which would cause hypothermia, then essentially the brain function is not effected. However, what will be effected is the ability to concentrate, focus and resist distraction. All of these will increase the probability of poor decision making and having an accident.
Most people will be able to resist colder temperatures for short periods without any symptoms of feeling cold, and the same is for motorcyclists. The longer the journey and time riding, the greater the affect of cold will be. By wearing extra layers or suitable winter motorcycle clothing will minimise the affect of cold and the heat loss of the body. There are also heating systems which may help to resist the cold, such as heated grips, heated vests and large accessory windscreens, handlebar muffs and guards which may protect from the cold.
One of the greatest problems a rider can face is being cold and wet which only compounds the problem further. Being wet speeds up the body cooling process as water is a much better conductor of heat, so having good waterproof clothing or waterproof over clothing will help to protect against this.
The motorcycle is affected in various ways, from engine performance to braking and handling.
Engine power is generally improved in colder temperatures as the air entering the cylinders is colder and hence more dense which means greater combustion which equals greater power.
Engine Oils & Gearbox/Transmission Oils will be thicker (more viscous) in colder temperatures which will mean they are less fluid and will not be as protective as when they are warmer. Oils have a recommended minimum operating temperature which is most crucial at first engine start of the day and in severe cold temperatures.
Brake fluid and braking is also effected by the cold temperatures, but not so noticeably. All fluids are designed to operate at a certain temperature range from very cold to hot and depending on the fluid specification will have different performance characteristics. When the brake lever/pedal is pressed the fluid, which resists compression, forces the brake pads or earlier shoes to the disc or drum which creates friction, the greater the heat the greater the friction up to a certain point. There are minute changes in the thickness of metals in the brakes and they will start at a colder temperature, however pads should be set to hug the disc which when is in motion generates heat, so the colder starting point is cancelled out to a certain degree. Under cold dry conditions, there is little a road rider will notice, but there might be some noticed at more aggressive speeds or on a race track. The differences in fluid specifications also allow for changes to the properties of the fluid under increasing operating temperatures. Under higher temperatures certain fluids under changing pressure will form gas bubbles which are highly compressible which will dramatically reduce braking performance. If the brakes are cold and wet, then there is less resistance and less friction which means less braking per a given lever/pedal setting, therefore the rider will have to apply more braking pressure to generate more heat and friction.
Tyres are probably the most effected component on the motorcycle with the variations in tyre pressure and the interaction with the road surface. When cold the volume of the tyre decreases and the pressure decreases within the contained space of the tyre. This results in the tyre being under inflated and may run slightly flat. This under inflation also causes the tyre to move and change shape under force which reduces its performance in handling and braking, increases wear and fuel consumption.
The tyre should be in good condition with adequate tread depth and the tyre pressure should be checked when the tyre is cold, which will ensure that the tyre operates at it’s best in the cold and wet.
Motorcycles tyres come with specifications that vary according to dry grip performance, wet grip performance, long distance hard wearing & economical, etc. Be sure that your tyres are road worthy and you are confident of their capabilities in the cold and wet conditions.
The road conditions may change dramatically during the winter months, be them wet, icy, leaves and debris, lifted oil residues which create an unstable layer between the tyre and road surface. This affects the interaction between the two and the result is that it affords less friction, hence less grip.
The road surface quality may also change in the cold and winter months with potholes and cracks forming from either water and ice affects or by traffic loading.
During cold periods, many agencies will treat the roads with deicing substances (salt, grit, chemicals) or rather anti icing substances which will only perform up to a certain point. Riding over these substances will provide less grip as another boundary layer is created between tyre and road.
A rider should constantly assess the condition of the road and be very mindful of anything that will dramatically reduce the performance of the tyres. Pay extra attention to weather forecasts and how that might affect the road surface.
Be prepared that the interaction between the tyres and road surface may decrease grip, handling, stability and braking performance.
Wear Clothing that keeps you warm and comfortable.
Be sure that your motorcycle is winter roadworthy.
Make sure that you feel ready to ride!
Acknowledge that there will be reduced handling and braking performance!
Think ahead, ride more conservatively and smoothly, be prepared for poor road conditions.