Why does the speed of the bicycle rarely rise in winter?


Winter is a tough season for those who are using bicycles to commute or go to school. The hands and ears that hold the steering wheel touch painful cold outside air or it gets slippery in the morning on a cold day as ice stretches in the middle of the night. Also, some people riding a bicycle on a daily basis say that there are also people claiming that the bicycle will become obviously difficult to proceed when it gets cold, and why such a phenomenon happens, news and columns on road bikes Deal withCyclistExplained.

Why do we ride slower in the cold? | Cyclist

The first thing to notice is "human" which is the bicycle engine. According to Dr. James Pearson who studies bioengineering at Cardiff · Metropolitan University, even if the outside is cold, as soon as exercise begins, the muscles contract and body temperature rises, but at the same time the human body contracts the blood vessels and regains body temperature I try to prevent escape to the outside. Therefore, it is difficult to moderately cool down the heat-up muscles immediately after exercising, which makes fatigue tend to accumulate easily. Also, even if you are in a lung suddenly of cold air you can not fully take in, oxygen absorption efficiency drops.

byElvert Barnes

However, according to Dr. Pearson, the muscles can cool down as the body gradually gets to the outside temperature, and oxygen can also be captured efficiently. In other words, it can not be said unequivocally that "the performance of exercise will be reduced if it is simply cold."

Next point to notice is "rubber of the tire". Actually, the higher the flexibility of the rubber of the tire the higher the tire's resistance to the roadRolling resistanceDecreases, and conversely, if the rubber of the tire becomes hard, the rolling resistance increases. Since the flexibility of rubber also varies with temperature, it can be said that when the outside air temperature decreases, the rubber becomes hard, the rolling resistance increases, and running becomes difficult.

SpecializedAccording to Wolf VormWalde, who is involved in tire production management at the company, the rolling resistance has changed by about 5% when the temperature changes by 8 degrees. Even if the rolling resistance is 10 to 20% of the total resistance experienced by the bicycle, it will be calculated to be less than 1% of the total resistance with a temperature change of 8 degrees. Furthermore, it is said that a new tire made of synthetic rubber is made so as to minimize the change in rolling resistance due to temperature and the influence of rolling resistance on the bicycle seems not to be so large.

byRichard Masoner / Cyclelicious

And it is the "big impact on bike than physiological phenomenon and rolling resistance"Air resistance"is. Because humans will ride a bicycle and give speed and will continue to collide with the air, it will receive resistance. Air resistance can be obtained by "air density" × "front projected area" × "drag coefficient" × "square of speed" ÷ 2.

For example, compare the resistance that the bicycle receives at the temperature of 28 degrees Celsius and the temperature of 10 degrees Celsius. When "the same person" rides on "the same bicycle" at the "same speed", the front projection area, the drag coefficient and the speed are the same, but since the air density changes when the temperature changes, the air resistance also changes in calculation . As for air density, not only temperature but also atmospheric pressure will be involved, but under the same atmospheric pressure conditionCalculate air density, The air temperature will be calculated to increase by 5 to 6% more than air temperature 10 degrees for air temperature 10 degrees. This means "Air resistance at 10 degrees Celsius will also increase by 6% from 28 degrees Celsius".

byMichael J. Slezak (JW)

Also, when you get on a bicycle with cold weather, the front projected area tends to become bigger than summer, and you will receive more air resistance. Since the air resistance occupies 70 to 90% of the total resistance which the bicycle receives, the effect of the increase in air resistance has a big influence, and it is said that the speed reduction of about 1 to 2 km / h can be seen from the experience.

When the temperature is low, the rolling resistance and the air resistance of the bicycle increase, so it can be argued based on the scientific basis that the bicycle is relatively difficult to proceed reliably in the winter. However, the fact that this fact has not been talked about so far has been concluded in the article that it is probably because everyone is not very interested in running by bicycle although it is cold outside.

byMikael Colville-Andersen

in Ride,   Science, Posted by log1i_yk