Be aware of crosswinds, especially in circumstances like a country road with high hedges where you are sheltered, until you reach a gate or other gaps in the hedge when there will be a sudden gust which can blow you off course or even off the bike, if you're not expecting it.
Understanding the weather...
- Thread starter rosscbrown
- Start date
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Predicting the arrival time at the end of a bike ride is a very difficult thing. There are lots of formulas, but I've not seen a formula to predict the cyclist's 'determination'. This only comes from experience, self appraisal and honesty.
The more times you miss the train, the more skilled you will become of assessing weather compensations.
The more times you miss the train, the more skilled you will become of assessing weather compensations.
ian turner
Guru
- Location
- Leicestershire
Ahem . Ho hum.
I've found with the met office forecasts not to trust them at more than 24 hours in advance. Preferably check the evening
before and if it's purely recreational then check on that day as their rain predictions have varied from the night before to the following morning.
Also if using their local weather maps check surrounding locations as sunny at your location may be rain 10 miles away. They don't give an overall average taking in surrounding areas.
asterix
Comrade Member
- Location
- Limoges or York
ian turner
Guru
- Location
- Leicestershire
Nein !! Waffe ist "weapon" im Englisch nicht "force" dumkopf
Indeed. "Luftwaffe" is not a direct translation of "Air Force".Nein !! Waffe ist "weapon" im Englisch nicht "force" dumkopf
Cold air is denser than warm air for a given pressure, thus the air resistance is higher, so you will cycle slightly slower during the winter than the summer.
So when the air temperature is minus 35 C, like when I was in Canada, I shouldn't have been able to move at all....
I didn't notice any difference. So with this in mind, I've made Q a constant of 1.20 kg/m^3.
And if anyone remembers the winter of 1981/82 when the ambient was minus 25C, I rode to work as normal and didn't notice any excessive drag.
Matthames
Über Member
- Location
- East Sussex
There is quite a lot I could write about with the OP, I will look into doing that later when I have a bit more time to go through it.
As for riding into the wind, it is the aerodynamics that will affect your overall speed. It is far from a simple addition or subtraction, it is dependent on the drag coefficient of the cyclist. The lower the drag coefficient the more easily a cyclist is able to slice through the air and thus the less energy is needed to propel the cyclist along. In simple terms if you have a head wind, just tuck yourself down into the most aerodynamic position you can.
As for cold affecting performance. The change of density of air with temperature is so small that it would only have a minor effect on performance. My guess is that the cold has more of an effect on the bodies biochemical systems affecting the amount of power you can output.
As for riding into the wind, it is the aerodynamics that will affect your overall speed. It is far from a simple addition or subtraction, it is dependent on the drag coefficient of the cyclist. The lower the drag coefficient the more easily a cyclist is able to slice through the air and thus the less energy is needed to propel the cyclist along. In simple terms if you have a head wind, just tuck yourself down into the most aerodynamic position you can.
As for cold affecting performance. The change of density of air with temperature is so small that it would only have a minor effect on performance. My guess is that the cold has more of an effect on the bodies biochemical systems affecting the amount of power you can output.
That's debateable. A guy on an ergometer in a refridgerated chamber, with a gun against his head, will output more than a guy on an ergometer in a sauna, threatened with the same gun.
Nah. The human body likes to work most efficiently when the air is at 33 deg C. At this temperature, there is no difference across the skin/boundary layer interface, so no energy is lost through convection.
In a gym where there is little breeze, the boundary layer around the body becomes 33 C, or close to. Then there is no energy lost through convection and the gym bike does not report these outgoing calories, only the calories spend turning the cranks.
my mate is a bit of a fair weather cyclist; if it's raining he don't leave the house. but he's got all weather keen recently and when i remind him of biking (friday evenings and sunday mornings usually) he's all "no, no it's gonna be pi**ing down" and so on when the weather forecast is no good, then he bitches when in fact it's not raining or windy or whatever.
not surprised if the Beeb ditch the met office; personally i just get out there and if it rains it rains.
that being said, i haven't bothered biking this weekend cos it's raining
stay in bed, drink tea
it's why god made rain
not surprised if the Beeb ditch the met office; personally i just get out there and if it rains it rains.
that being said, i haven't bothered biking this weekend cos it's raining
stay in bed, drink tea
it's why god made rain
Davidc
Guru
- Location
- Somerset UK
Apart from preferring not to ride in the rain, especially the torrential sort, I always look out for temperatures.
The worst thing for discomfort and loss of power is feeling too hot or too cold. If I'm planning a ride I mainly decide what to put in the pannier or bag based on that.
Perhaps it's a location thing, but this year I've found the Met Office (aka BBC weather) very good for advance forecasts (2 days and upwards) and MetCheck best for the next 24 hours. Last year it was the other way round. FWIW I suspect the BBC contract will go to whoever is cheapest, best won't come into it.
The worst thing for discomfort and loss of power is feeling too hot or too cold. If I'm planning a ride I mainly decide what to put in the pannier or bag based on that.
Perhaps it's a location thing, but this year I've found the Met Office (aka BBC weather) very good for advance forecasts (2 days and upwards) and MetCheck best for the next 24 hours. Last year it was the other way round. FWIW I suspect the BBC contract will go to whoever is cheapest, best won't come into it.
So when the air temperature is minus 35 C, like when I was in Canada, I shouldn't have been able to move at all....
I didn't notice any difference. So with this in mind, I've made Q a constant of 1.20 kg/m^3.
And if anyone remembers the winter of 1981/82 when the ambient was minus 25C, I rode to work as normal and didn't notice any excessive drag.
I don't notice any extra drag with my hub dynamo, but there clearly is some as you can't produce energy from nothing.
I am certainly slower during the winter than the summer, as measured by my cycle computer, plus my car is slightly less economical during the winter months as well (although that could be partly down to the fuel).
Which goes against the point you are trying to make, as colder, denser air makes the engine more efficient.
Maybe there are other factors which you aren't taking into account. For instance, is the traffic generally slower in the winter, because more people drive rather than ride or walk?
