# Understanding the weather...



## rosscbrown (30 Sep 2010)

Confession: I'm a bit of an idiot.

Having got that out of the way, on to my question: how big an impact does the weather have on cycling?

So far I've managed to live my life largely ignorant to the weather conditions outside. I'm not to hot on the seasons nor am I particularly good at noticing patterns in the weather. Before I started cycling I can't say I cared much about what was going on outside. I rarely looked at a forecast. If it was wet outside, I got wet and so on.

But now, I've started looking at the weather, as now I have to decide if I'm going to bike to my destination or jump in a taxi.

I've worked out the following: the wind typically blows west to east (where I stay anyway) and that living on the east end of town is demoralising.

Things I would like to know: 

1) How regular is the weather, I've observed a pattern of east to west wind in Edinburgh. Is this likely to be the case for a long time or is it just coincidence.

2) Looking at the forecast for tomorrow, I'm seeing a mean wind speed of 12mph with gusts as high as 35mph. My current average cycling speed is in the region of 14mph. 14mph into a 12mph headwind should see me progressing at 2 miles per hour? Somehow I don't think that's the case. How does (head)wind speed impact on cycling speed? I'm guessing that I'll cycle harder to compensate - how would I go about measuring that?

3) Assuming it is just raining, no wind, what kind of impact does that have on my cycling. I feel like I slow down, owing to road conditions, so I can't really tell if rain makes cycling easier or harder.

4) Thunder and lightening. Very very frightening. Namely the lightening, is it safe to be out in such weather. How does being on a bicycle adjust one's chances of being stuck by lightening?

I'm not too sure what the cold does to my cycling - I'd guess there might be some loss of efficiency because my body has to work harder to keep me warm, but to be honest I haven't really noticed anything. Then again I'm not particularly focused on training; I cycle mostly for transport/recreation. My questions are more of an intelectual pursuit...

Also I'm sure different weather conditions have a mechanical impact on the bike's performance. Right now I'm mostly interested on the impact on me as a person.

So those are my stupid weather questions. Maybe you can help me out with a few answers or links in the right direction. Then again, perhaps I'm beyond helping out...


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## gbb (30 Sep 2010)

Certainly where i live Ross, theres a prodominantly easterly wind, thats to say a good proportion of the time i'll have a head wind going home, tailwind going to work. It varies regularly of course.

Headwind ?...i dont know how you'd calculate it into your progress. All i know is i don't try to beat it, you just get cream crackered. I just find a pace, however fast or slow that is, that works and accept it.

Rain...can't really say it has any impact other than as you state, it makes me more cautious on bends. Otherwise, no difference.

Thunder n lightning...i reckon there's very little chance of being hit anyway...although i remember one storm i got stuck in, huge lightning flashes nearby, the thought's a scary one. But then you can't take shelter under a tree !!

I slow down significantly in the winter...i just can't get the muscles going. I always notice that.


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## jimboalee (30 Sep 2010)

Move this thread into 'Know how' and I will explain all.


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## byegad (30 Sep 2010)

Some observations.
1. Yes most of the UK has a predominantly West to East air stream. The most common direction is actually from a bit South of West.

2. I average 11mph or thereabouts, but on a windy day, like your forecast, I have never cycled backwards at 1mph.  You'll find cycling dead into the wind slower than normal, but it's not a simple subtraction. Equally, you'll fly along woth the wind behind you, but again it's not a simple addition. On windy days rollng countryside is easier to ride in than dead flat countryside. You get gravity's help down hill into the wind and some shelter in the lee of a hill as you climb into the wind. 


3. Rain, or rather wet roads raises grip issues. You need to avoid riding over white lines or metal drain covers in other than a straight line without braking. Both are likely to be very slippery and bring you down. The rain falling on you will have a minimal slowing effect. The weight of water is brought up to your speed before it drips off. However, as I said, this is likely to have no measurable effect. Some people think rolling resistance of tyres is slightly less on wet roads, so you'll go a bit faster.

4. Lightening can be dangerous. On an upright bike you will be a bit higher and the metal of the bike will have an attraction effect. A strike could be fatal. I was taught to lie down in a thunderstorm if on high ground, we used to hike over the North Yorks Moors and on the tops a human is the tallest thing for miles around. I only did it once when we got caught in a real storm above Westerdale and have never needed to do it while riding. In a town or in wooded country you will not be the highest thing and so will be OK, so long as you don't shelter under a tree. 

Mechanically the main effect of rain is on brakes. Unless you have drum brakes the braking surface will be wet so the first wheel rotation or two will have less braking than the rest as the pads wipe off the excess water, and grit on rims. Brake early and be prepared for the brakes to suddenly get better for the same application force. The chain will need to be well lubed to avoid rusting and many people dry their chains after a wet ride. I use a light spray of GT85 to rive the water off. 


Physically for you the issue is how you cycle. 

I tend to aim for a pretty constant effort, accepting that I'll climb slowly in a low gear and so don't get too sweaty while riding. I'm also prone to seize up if cold and wet so I go for a breathable waterproof which emphasises waterproof. Others don't mind being wet, after all you'll soon dry if you are working hard, and so go for a 'waterproof' that may let in some rain but allows the sweat to breathe out easily. Only you can decide on this. 

In any case in the cold you must be 'warm enough' to avoid hypothermia. Most cyclist naturally work a bit harder on the bike if they're cold but if it's 1 degree C and raining/sleeting hard you will want warm hands to operate important things like brakes so if you're going to ride in those conditions some good waterproof gloves are a must in my opinion.


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## asterix (30 Sep 2010)

Clearly the OP is not a bit of an idiot and byegad's reply is very good. I would add that I find it's best for me if I start out of the house feeling a little bit chilly and soon warm up. If I dress to be warm immediately I soon get too hot. It's always best to use 'layering' - have several layers of clothing so its easily adjustable. e.g. base layer, jersey, jacket. (I've never had a waterproof jacket that doesn't make me wet from the inside!)


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## Norm (30 Sep 2010)

Good answer from byegad, but I do have a few bits to add / change.



byegad said:


> 2. I average 11mph or thereabouts, but on a windy day, like your forecast, I have never cycled backwards at 1mph.  You'll find cycling dead into the wind slower than normal, but it's not a simple subtraction.


 IIRC, the wind resistance increases with the square of the speed, so only you'll lose two or three mph.



byegad said:


> 3. Rain, or rather wet roads raises grip issues. You need to avoid riding over white lines or metal drain covers in other than a straight line without braking. Both are likely to be very slippery and bring you down. The rain falling on you will have a minimal slowing effect. The weight of water is brought up to your speed before it drips off. However, as I said, this is likely to have no measurable effect. Some people think rolling resistance of tyres is slightly less on wet roads, so you'll go a bit faster.


Definitely watch for metal and paint, as well as the over-banding used around road works and be careful of puddles which might be deeper than expected. Oh, and on the subject of painted surfaces, always aim for the black bits of a zebra crossing.

Of more frequent concern is that water makes grit stick to tyres and it lubricates the grit's passage through the tyres, making punctures in the rain much more likely. 



byegad said:


> 4. Lightening can be dangerous. On an upright bike you will be a bit higher and the metal of the bike will have an attraction effect. A strike could be fatal.


Light*e*ning is not dangerous, many think it has health benefits. Lightning, though, can be nasty. 

I'd have thought, though, that the tyres would act as a good insulator, more than offsetting any metal on the bike.


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## jimboalee (30 Sep 2010)

FL = 0.5 * Q * Cd * A * *V^2
*
Sorry Admin. 

V^2, The square of the speed Norm was talking about.


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## Norm (30 Sep 2010)

jimboalee said:


> FL = 0.5 * Q * Cd * A * *V^2
> *
> Sorry Admin.
> 
> V^2, The square of the speed Norm was talking about.


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## summerdays (30 Sep 2010)

Wind can be a pain but you would be surprised what strength winds you can cycle in ... often it is gusty, I've cycled in gusts upto 45 mph, but not great distances and you have to be very wary of the effect of passing vehicles or buildings first protecting you and then exposing you to the wind. Its also a strange experience when you are having to actually cycle downhill into the wind. The worst winds are cross-winds for the potential to blow you into the path of traffic.

Rain often isn't as bad as it looks but its at its worst in the middle of winter when you can get cold quite quickly.

Hail can be nasty though - painful cycling through it.


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## jimboalee (30 Sep 2010)

Norm said:


>



BTW 

FL is Force luft in Newtons.


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## Norm (30 Sep 2010)

jimboalee said:


> BTW
> 
> FL is Force luft in Newtons.


I was trying to get air or wind or resistance or drag or whatever out of it. 

I never thought to go German.


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## HJ (30 Sep 2010)

Edinburgh is a windy place, that is just the way it is, you'll get used to it. When it is in you face, use a lower gear and keep your cadence the same, when it is behind you cover the brakes and enjoy the ride. Anything below 20mph (ave) isn't really a great problem, above that thing can get interesting. Don't take the forecasts too seriously, the accuracy for wind speed, particularly the gusts, is really quite poor...


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## Lien Sdrawde (1 Oct 2010)

Ive been keen on 'weather watching' for most of my life but have observed it with great passion for about 11 years.

Two things that may help.

1. Ignore all BBC national weather information - I beleive they're going to ditch their contract with the met office cos things have been so bad. 

2. A few years ago I was invited to one of those survival courses (it was filmed by Channel 4). It was run by a guy called Lofty who was the survival expert in the SAS. He had just written a book which he kindly gave us all a signed copy of.....

getting to the point now.....

In it are easily identifiable pictures of clouds and info on the height of clouds - and what is likely to happen when these clouds appear.
It is by far the best indication of what the weather is going to do in your area, wherever you are in the world. I cant tell you how often this information has helped us. You literally know wether to stay out for the day or head for the exits before everybody else and his dog does.

Like they say, if you want to know what the weather is doing, look out of the window. 

The book I mentioned also comes in a pocket version now as well + its full of other great bits. I think you can buy it for just over £2 - link below.

SAS book link


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## jimboalee (1 Oct 2010)

Lien Sdrawde said:


> Ive been keen on 'weather watching' for most of my life but have observed it with great passion for about 11 years.
> 
> Two things that may help.
> 
> ...



I've met Lofty. Great guy.

The fly in your ointment is assessing what the weather is going to be at 05:30 the next morning for a ride to the railway station.
Take yesterday for instance. Last evening, I took a lovely ride to Tesco in the calm evening ( cloudless ) sunshine. This morning, it is blowing up a gale with gusts to 45 mph.

I checked the forecast last night and for those who will be cycling against the wind to catch the train, leave home 10 minutes earlier!


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## Firestorm (1 Oct 2010)

One thing to add, which may be more a motorcyclist thing, as well as the paint, whitelines overbanding mentioned above, keep an eye out for those "rainbows" on the road, that is a sign of oil / diesel, particularly corners and roundabouts

This is one advantage of the wet weather, you can see the damn stuff, in the dry its nigh on invisible. 

Whatever the weather I take greater care on any roundabouts with petrol stations nearby, the amount of small fuel spills caused by vehicles filling to the brim and the overflowing as they go round a roundabout is stupidly high


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## tyred (1 Oct 2010)

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.


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## jimboalee (1 Oct 2010)

Don't try to tack into the wind.


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## jimboalee (1 Oct 2010)

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.


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## ian turner (1 Oct 2010)

Lien Sdrawde said:


> 1. Ignore all BBC national weather information - I beleive they're going to ditch their contract with the met office cos things have been so bad.


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.


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## asterix (1 Oct 2010)

jimboalee said:


> BTW
> 
> FL is Force luft in Newtons.




a.k.a Luftwaffe?


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## ian turner (1 Oct 2010)

asterix said:


> a.k.a Luftwaffe?


Nein !! Waffe ist "weapon" im Englisch nicht "force" dumkopf


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## Norm (1 Oct 2010)

ian turner said:


> Nein !! Waffe ist "weapon" im Englisch nicht "force" dumkopf


Indeed. "Luftwaffe" is not a direct translation of "Air Force".


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## al78 (1 Oct 2010)

rosscbrown said:


> I'm not too sure what the cold does to my cycling - I'd guess there might be some loss of efficiency because my body has to work harder to keep me warm, but to be honest I haven't really noticed anything. Then again I'm not particularly focused on training; I cycle mostly for transport/recreation. My questions are more of an intelectual pursuit...



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.


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## jimboalee (1 Oct 2010)

al78 said:


> 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.


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## Matthames (2 Oct 2010)

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.


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## jimboalee (2 Oct 2010)

Matthames said:


> 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.
> 
> ...



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.


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## the_bing (3 Oct 2010)

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


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## Davidc (3 Oct 2010)

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.


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## al78 (3 Oct 2010)

jimboalee said:


> 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).


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## Norm (3 Oct 2010)

al78 said:


> ...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?


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## jimboalee (3 Oct 2010)

Norm said:


> 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?




That'll be the 'Cranking offset' and 'afterstart enrichment map' adding fuel richer than Stoic to get the thing going in colder ambient soaks. Plus you will have lights on more, heater blower on etc which will load up the alternator.


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## Matthames (3 Oct 2010)

I said I was going to answer the questions raised in the OP. So here they are:



rosscbrown said:


> 1) How regular is the weather, I've observed a pattern of east to west wind in Edinburgh. Is this likely to be the case for a long time or is it just coincidence.



Generally the UK has predominately westerly (West to East) patten of wind. This is mainly due to the latitude we are at, plus the fact that we sit on the eastern edge of a large ocean basin, this tends to mean we sit in the cross hairs of some pretty wild and unpredictable weather. This weather normally blows west to east. However, local orography (terrain) can influence the wind on a local level. So if east to west in Edinburgh is the norm then I would put it down to local quirks in the climate. 



rosscbrown said:


> 2) Looking at the forecast for tomorrow, I'm seeing a mean wind speed of 12mph with gusts as high as 35mph. My current average cycling speed is in the region of 14mph. 14mph into a 12mph headwind should see me progressing at 2 miles per hour? Somehow I don't think that's the case. How does (head)wind speed impact on cycling speed? I'm guessing that I'll cycle harder to compensate - how would I go about measuring that?



The only time that you would be worrying about cycling at 14mph and only making progress at 2mph is if you were cycling on a conveyor belt. Cycling into a headwind would only slow you down according to the amount of drag you are creating. Personally I wouldn't bother with numbers, the maths involved is horrific and not really worth loosing any sleep over. If you are worrying about the figures then you would probably be somebody with eyes for first place in a TT world championship. 



rosscbrown said:


> 3) Assuming it is just raining, no wind, what kind of impact does that have on my cycling. I feel like I slow down, owing to road conditions, so I can't really tell if rain makes cycling easier or harder.



Having been caught out in the rain yesterday, I have noticed that it makes things that bit harder. I found that I slowed down by a third of the speed I normally do in the dry. This was mainly because of the rain stinging my eyes. It is a lot more wearing than dry conditions. The trick I have found is to just keep cycling as much as you can, if you are wearing the right clothes the water will trap between your skin and the layer of clothes like a wet suit. Like a wet suit, your body will heat this layer of water, keeping you nice and warm. 



rosscbrown said:


> 4) Thunder and lightening. Very very frightening. Namely the lightening, is it safe to be out in such weather. How does being on a bicycle adjust one's chances of being stuck by lightening?



Personally I wouldn't chance it. Have a go at riding under electricity pylons and you will quickly find out why. If you can get a painful but harmless poke from that, then imagine what would happen if a metal object passed under a charged cloud.


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## HLaB (3 Oct 2010)

Things have probably been answered but here's my take on it.



rosscbrown said:


> 1) How regular is the weather, I've observed a pattern of east to west wind in Edinburgh. Is this likely to be the case for a long time or is it just coincidence.



The pattern is actually west to east. There's a fairly predominant west wind blows through the central belt meaning predominantly weather is blown over from the west. ie if its wet in Glasgow in the morning, it'll probably be wet in Falkirk in the afternoon and wet in Edinburgh at night. However the rain can sometimes 'wear out' before it gets here. A look at a weater radar usually confirms thi but be prepared its occaisionaly not the case, usually when I cycle West and expect to be blown home.



> 2) Looking at the forecast for tomorrow, I'm seeing a mean wind speed of 12mph with gusts as high as 35mph. My current average cycling speed is in the region of 14mph. 14mph into a 12mph headwind should see me progressing at 2 miles per hour? Somehow I don't think that's the case. How does (head)wind speed impact on cycling speed? I'm guessing that I'll cycle harder to compensate - how would I go about measuring that?



When there's a head wind you still get some where just not as fast. Individual air particles are travelling, say 12mph but because air is a gas some of the particles go around you so it depends how much of the particles you have to stop/ resist. Basically if you normally cycle 15mph without wind you can expect for the same effort into a head wind to be slown dow by around 1-2mph.



> 3) Assuming it is just raining, no wind, what kind of impact does that have on my cycling. I feel like I slow down, owing to road conditions, so I can't really tell if rain makes cycling easier or harder.



Depending on the level sometimes wet surfaces can be slightly easier as there is less rolling resistance (the water acts like a lubricant). When it gets too heavy though it starts to weigh you down and the rolling resistance actually increase. Its normal though to be more cautious in the wet, so generally it slows you down.



> 4) Thunder and lightening. Very very frightening. Namely the lightening, is it safe to be out in such weather. How does being on a bicycle adjust one's chances of being stuck by lightening?



Thunder and lightening happens so rarely here I wouldn't worry about it. Even if it does occur the chances of actually being struck on a moving object is limited. How many cars/ buses/ lorries do you hear about being struck in the East of Scotland.



> I'm not too sure what the cold does to my cycling - I'd guess there might be some loss of efficiency because my body has to work harder to keep me warm, but to be honest I haven't really noticed anything. Then again I'm not particularly focused on training; I cycle mostly for transport/recreation. My questions are more of an intelectual pursuit...



Cold depending on its level doesn't have too much impact on the bike but it does on you (the engine) and again if its too eaxtreme (too cold) there's a risk of ice which you have to be cautious of too so this slows you down or rain turns to snow and slows both you and the bike down. The good thin when its frosty you don't have to get up extra early to scrape you windscreen etc.


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## Chutzpah (3 Oct 2010)

HLaB said:


> Thunder and lightening happens so rarely here I wouldn't worry about it. Even if it does occur the chances of actually being struck on a moving object is limited. How many cars/ buses/ lorries do you hear about being struck in the East of Scotland.



Being in a motor vehicle is a brilliant place to be in a thunderstorm. Perfect Faraday cage. Having watched cars get hit by man-made lightning on the TV, I'm not entirely sure if you'd notice to be honest...

I think the only time I would worry about lightning whilst cycling was if I was in the middle of a moor. In town I'm guessing the chances of getting struck are low.


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## al78 (4 Oct 2010)

Norm said:


> Which goes against the point you are trying to make, as colder, denser air makes the engine more efficient.



I wasn't aware of that, but anyway, it seems that effect is more than compensated by other factors, like as someone mentioned extra load on the engine from heating and lights, plus a small amount due to increased drag.



Norm said:


> 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?



I have a rural commute; traffic levels are constant throughout the year (i.e. free flowing).


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## Sheepy1209 (4 Oct 2010)

Take a look at this chart: windfinder.com stats for Edinburgh.
It shows a strong bias to west-south-westerly over most of the last year.

Contrast with Blackpool: Windfinder.com stats for Blackpool
Here we have a predominant westerly flow, but much more variation in its direction.

As Blackpool is on the west coast we're exposed to wind from any westerly point (and lots of it too); I suspect that topography funnels Edinburgh's winds down a narrow south-westerly direction.

Another thing we get here is that in the spring and summer a warm calm day will trigger a north-westerly sea breeze - you might find the same happening in Edinburgh, maybe the April - June switch is related to sea breezes?


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## jimboalee (4 Oct 2010)

In the early stages of a cyclist's life, wind strength and direction is a big thing.

After a couple of decades, wind becomes less of an annoyance.

Its something that must be ridden in. With or against.

Only on a few unfortunate days will the wind turn to be against both morning and evening. IE it all averages out in the end.

If the prevailing wind in Edinburgh is SW, it means that the majority of bike rides are against the wind out, and have a tail wind home. Think yourselves lucky, as a tail wind out gives a false impression of ease, and then when the cyclist turns for home, he's against a gale all the way.

I always ride Audax DIYs against the wind outwards. This gives me a nice easy ride home.


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## asterix (4 Oct 2010)

On most points of the compass the wind will appear to be against you when cycling, especially when you turn for home


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## davefb (4 Oct 2010)

asterix said:


> On most points of the compass the wind will appear to be against you when cycling, especially when you turn for home



but its TRUE!!!!


would point out re 'bbc forecasts' , the main 'problem' people forget is generally the 'air' moves, but you dont know exactly how fast it moves. but we want to know what will occur at a specific point in time (and how that specific bit or air will react as it hits a location). what you need to listen in the forecast isnt the point specific 'it will rain at 10pm' then moan that it rains at 945 or 1030, but look at the overall motion of the weather pattern ( some of the forecasts are better on this).. 

or at least thats what happens when the fronts move over ( which is what the lofty guy is talking about when he speaks about looking for specific cloud formations).

if you have either a big low or a big high sat on the country, then you'll get constant conditions and more accurate forecasts..

obviously local knowledge is useful, like 'it will always rain in bolton'


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## HLaB (4 Oct 2010)

jimboalee said:


> If the prevailing wind in Edinburgh is SW, it means that the majority of bike rides are against the wind out, and have a tail wind home.




Lol, you are right, but the majority of my rides in Lothian (club runs) have a tail wind out and a head wind home. Most rides go to East Lothian though as the roads are generally quieter and its generally drier. For some reason you only notice the head winds


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## Norm (4 Oct 2010)

Sheepy1209 said:


> Another thing we get here is that in the spring and summer a warm calm day will trigger a north-westerly sea breeze - you might find the same happening in Edinburgh, maybe the April - June switch is related to sea breezes?


That is what a "sea breeze" is all about.

Specifically, a sea breeze is the onshore wind in the afternoon of a warm day, and the offshore wind before sun-rise, caused by land and water heating, and cooling, at different rates.



asterix said:


> On most points of the compass the wind will appear to be against you when cycling, especially when you turn for home


The difference between true wind direction and apparent wind direction.


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## rosscbrown (5 Oct 2010)

Thanks for all the info - glad my question wasn't too silly. I've learned quite a bit :-)


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## jimboalee (5 Oct 2010)

Strap one of these to your handlebars and you'll know how hard you are working.


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## decca234uk (5 Oct 2010)

I stopped worrying about the weather years ago. if we allow ourselves to be rules by it we'd never get out in this country. if it's absolutely chucking it down, monsoon type of rain, I won't use my bike, I won't get it out in snow or freezing sleet, apart from that I just get on with it. My favourite cycling conditions are coming off the night shift on a fresh cold winter's morning. Amazing how fast you can go when the air's freezing.


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## Lien Sdrawde (6 Oct 2010)

rosscbrown said:


> Thanks for all the info - glad my question wasn't too silly. I've learned quite a bit :-)



It is probably (and quite rightly so) our nations favourite subject.


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## Arch (6 Oct 2010)

Just one correction to something said above, about lightning. Don't lie down if caught in the open. Crouch, on the balls of your feet. You want as little surface area contact with the ground as possible. And tuck your head down as low as you can. If you can stand you bike up a little way away, all the better, as it'll be taller than you.

Your tyres will do nothing to insulate you. A lightning bolt has jumped hundreds of metres through the air, an inch of rubber won't hinder it.


I have been caught out, coming over the Trough of Bowland, moorland with nothing higher than a fence for miles, except me. When the lightning appeared to be coming down in the field to my left, I jumped off, propped the bike on its kickstand and crouched down, having a vague recollection that that was the thing to do. The next flash appeared to be in the field to my right....

When I got home, I made a point of looking up the correct thing to do, and was glad to find I'd been right.


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## ufkacbln (6 Oct 2010)




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## byegad (6 Oct 2010)

Firestorm said:


> One thing to add, which may be more a motorcyclist thing, as well as the paint, whitelines overbanding mentioned above, keep an eye out for those "rainbows" on the road, that is a sign of oil / diesel, particularly corners and roundabouts
> 
> This is one advantage of the wet weather, you can see the damn stuff, in the dry its nigh on invisible.
> 
> Whatever the weather I take greater care on any roundabouts with petrol stations nearby, the amount of small fuel spills caused by vehicles filling to the brim and the overflowing as they go round a roundabout is stupidly high



Good point. Riding three wheels has made me complacent.


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## Lien Sdrawde (7 Oct 2010)

Even if lightening strikes close to you, you may not feel your best afterwards - a fine famous example HERE


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## Lien Sdrawde (7 Oct 2010)

Oh, and my favourite weather phenomenon - sundogs - you probably never noticed them before, but you'll be looking for them from now on.

I love the weather


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## davefb (9 Oct 2010)

Lien Sdrawde said:


> Oh, and my favourite weather phenomenon - sundogs - you probably never noticed them before, but you'll be looking for them from now on.
> 
> I love the weather



/like


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## stevieboy378 (9 Oct 2010)

Lien Sdrawde said:


> Oh, and my favourite weather phenomenon - sundogs - you probably never noticed them before, but you'll be looking for them from now on.
> 
> I love the weather



My favourite weather phenomenon - the Brocken Spectre :


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## Matthames (9 Oct 2010)

stevieboy378 said:


> My favourite weather phenomenon - the Brocken Spectre :



Knowing the physics behind various optical phenomenon they don't take you by surprise, you instinctively know when to expect them and actually go looking for them. I can spot a rainbow without even having to look for it, plus I know exactly where to look for it when I want to see it.

For me personally, I don't find the colours in a rainbow that fascinating, I am interested in the part of a rainbow most people don't even notice much. A rainbow is usually accompanied by another bow which is the exact opposite. Between the primary and secondary bow there is a dark band and in the middle of the arc of the primary bow everything is lighter. The dark band is called Alexander's dark band and is produced because light cannot be reflected back to the viewer at a certain angle. 

Sun dogs can be used as a rather crude weather forecasting observation. If you see sun dogs in the west you can sure as bet that the day after it would be chucking it down.


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## summerdays (10 Oct 2010)

Matthames said:


> Knowing the physics behind various optical phenomenon they don't take you by surprise, you instinctively know when to expect them and actually go looking for them. I can spot a rainbow without even having to look for it, plus I know exactly where to look for it when I want to see it.
> 
> For me personally, I don't find the colours in a rainbow that fascinating, I am interested in the part of a rainbow most people don't even notice much. A rainbow is usually accompanied by another bow which is the exact opposite. Between the primary and secondary bow there is a dark band and in the middle of the arc of the primary bow everything is lighter. The dark band is called Alexander's dark band and is produced because light cannot be reflected back to the viewer at a certain angle.
> 
> Sun dogs can be used as a rather crude weather forecasting observation. If you see sun dogs in the west you can sure as bet that the day after it would be chucking it down.



Observing the weather gradually builds your knowledge as well ... I can be in my house and notice the change in light levels that often indicates that its about to rain ... and usually rush out trying to save my washing before it starts within a minutes (seconds) of me noticing the fall in light levels. 

I must admit I love a double rainbow and usually watch out for it if the rain is heavy enough - last good one I was on the motorway in August unfortunately as you could almost see the complete arch.


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## jimboalee (10 Oct 2010)

summerdays said:


> Observing the weather gradually builds your knowledge as well ... I can be in my house and notice the change in light levels that often indicates that its about to rain ... and usually rush out trying to save my washing before it starts within a minutes (seconds) of me noticing the fall in light levels.
> 
> I must admit I love a double rainbow and usually watch out for it if the rain is heavy enough - last good one I was on the motorway in August unfortunately as you could almost see the complete *arch*.




That's bloody good going to see Arch.


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## Jaguar (11 Oct 2010)

summerdays said:


> The worst winds are cross-winds for the potential to blow you into the path of traffic.



It's always windy here, on the east coast. I hate it, hate it. The prevailing wind is southerly, but every few days (or even mid-ride) it switches round to northerly.


I've only been brought down once by a white line: 
View: http://www.youtube.com/watch?v=TDHq_Jop_k8



I've cycled in thunderstorms too; the advice I read re: lightning is to lie down in the road


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## Willo (11 Oct 2010)

Being quite fascinated by the weather, somehow this thread passed me by so will have a good read. In the meantime, and dumbing down the discussion, is it just me or is a wind always a bloomin head wind . I went out for a spin this morning, 20 miles but the first time I'd done anything over my 6 mile commute since my holiday over a month back. I was a little worried when I set off with it being pretty windy, and my fears were confirmed about 7 miles in I was really suffering. Thing was I went in a long loop and whatever direction I faced the wind was coming at me; the best it got was a kind of diagonal head on but headwind it remained  Anyway, I battled on and wasn't much slower than usual but the legs certainly felt the workout.


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## jimboalee (11 Oct 2010)

The wind was 14 mph this morning. I was riding at 17 to 18 mph. At some parts of my ride, there was just a faint whisp on my face. A 3 to 4 mph whisp.

On my return this evening, the wind was still at 14ish mph. I was at 14 to 15 mph, so on those 'head on' sections, there was a 29 mph whisp on my face.


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## darth vadar (11 Oct 2010)

Another fascinating thread.

I started reading it and then couldn't stop!

Lots of people trying to do their best to be more 'intellectual' that the previous contributor.

I know that the weather is the most talked about topic in the UK, but does it really warrant four pages of mind numbing nonsense.

The weather is easy to understand. You look out the window or poke your nose out the front door. If its raining or cold you wear something waterproof or warm, and if its nice and sunny you wear a tee shirt and shorts!! If you aren't sure, then stick a coat, a jumper or a pair of long pants in a bag and carry it with you. 

It seems to have worked for me for the last 40+ years.


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## jimboalee (12 Oct 2010)

darth vadar said:


> Another fascinating thread.
> 
> I started reading it and then couldn't stop!
> 
> ...



"stick a coat, a jumper or a pair of long pants in a bag and carry it with you." & "mind numbing nonsense".

Says it all.


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## Canardly (16 Oct 2010)

Can cope with most things, but wind is the one I dislike most.


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## Browser (17 Oct 2010)

Matthames said:


> Personally I wouldn't chance it. Have a go at riding under electricity pylons and you will quickly find out why. If you can get a painful but harmless poke from that, then imagine what would happen if a metal object passed under a charged cloud.




Sorry, are you saying you can get a belt from cycling under a pylon? I walk under the things all of the time at work and have cycled under them hundreds of times, up and including those carrying 400kv, and have never even felt a tingle. I've also had occasion to switch in our 132kv sub in the fog, similar result. You can certainly hear the pan-of-bacon-from-hell crackling from the insulators, but that's about all.


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## Matthames (18 Oct 2010)

Browser said:


> Sorry, are you saying you can get a belt from cycling under a pylon? I walk under the things all of the time at work and have cycled under them hundreds of times, up and including those carrying 400kv, and have never even felt a tingle. I've also had occasion to switch in our 132kv sub in the fog, similar result. You can certainly hear the pan-of-bacon-from-hell crackling from the insulators, but that's about all.



If you don't earth yourself riding under a pylon, the electromagnetic field produced by the current running through the wires will cause you to become electro statically charged, so if you were to earth yourself, say by touching a metal brake lever before the charge had chance to dissipate slowly you will get a static shock. I had it happen to me once, I rode under some electric cable as it crossed a road. Went to touch the brakes and got a bit of a poke from the static. The way I have learnt to avoid something like that is to touch something metal as you ride underneath and it prevents a charge from building up.


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## jimboalee (18 Oct 2010)

If you take a flourescent tube under a HV cable, you can do a good impersonation of Luke Skywalker.


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## snailracer (18 Oct 2010)

jimboalee said:


> FL = 0.5 * Q * Cd * A * *V^2
> *
> Sorry Admin.
> 
> V^2, The square of the speed Norm was talking about.


Correct, however:

Power = FL * V

Therefore, power is proportional to velocity _cubed_.

If you are riding 30mph into a 3 mph headwind (ie almost none), your windspeed increases from 30mph to 33mph, and you would need to put out an extra 32% of power, which is significant.


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## jimboalee (19 Oct 2010)

snailracer said:


> Correct, however:
> 
> Power = FL * V
> 
> ...



Pf = ( Crr x (W/375) x V ) + ( CdA x (V^2/391) * (V/375) )

How does that grab you? 

30 to 33 mph headwind on my Dawes Giro 500 is 30.2 % more power requirement. It is ONLY the Airspeed that is changing. Tyre deformation and geartrain losses remain the same.


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## darth vadar (19 Oct 2010)

jimboalee said:


> Pf = ( Crr x (W/375) x V ) + ( CdA x (V^2/391) * (V/375) )
> 
> How does that grab you?
> 
> 30 to 33 mph headwind on my Dawes Giro 500 is 30.2 % more power requirement. It is ONLY the Airspeed that is changing. Tyre deformation and geartrain losses remain the same.




Blimey !

I bet the winter nights just fly by in your house.


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## snailracer (19 Oct 2010)

jimboalee said:


> Pf = ( Crr x (W/375) x V ) + ( CdA x (V^2/391) * (V/375) )
> 
> How does that grab you?
> 
> 30 to 33 mph headwind on my Dawes Giro 500 is 30.2 % more power requirement. It is ONLY the Airspeed that is changing. Tyre deformation and *geartrain losses remain the same*.


Geartrain losses increase because power has increased.

If the gears are 95% efficient, and 30.2% more power is being transmitted, then the geartrain losses add 0.302 * 0.05 = 1.51% extra.

30.2% + 1.51% = 31.71%


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## jimboalee (19 Oct 2010)

snailracer said:


> Geartrain losses increase because power has increased.
> 
> If the gears are 95% efficient, and 30.2% more power is being transmitted, then the geartrain losses add 0.302 * 0.05 = 1.51% extra.
> 
> 30.2% + 1.51% = 31.71%



Oil or no oil?


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## jimboalee (20 Oct 2010)

This is from a handout I was given before working in Canada.


Deg C Windchill.



0 to -9 

Low - Slight increase in discomfort 

 - Dress warmly, with the outside temperature in mind. 



-10 to -27

Low - Uncomfortable
- Risk of hypothermia if outside for long periods without adequate protection

 - Dress in layers of warm clothing, with an outer layer that is wind-resistant.
- Wear a hat, mittens and scarf. - Keep active. 



-28 to -39

Increasing risk: 

 - Exposed skin can freeze in 10 to 30 minutes

- Check face and extremities (fingers, toes, ears and nose) for numbness or whiteness 
- Risk of hypothermia if outside for long periods without adequate protection

- Dress in layers of warm clothing, with an outer layer that is wind-resistant.
- Cover exposed skin: wear a hat, mittens and a scarf, neck tube or face mask.
- Keep active. 



-40 to -47

High risk: exposed skin can freeze in 5 to 10 minutes*

- Check face and extremities (fingers, toes, ears and nose) for numbness or whiteness (frostbite)
- Risk of hypothermia if outside for long periods without adequate protection - Dress in layers of warm clothing, with an outer layer that is wind-resistant.
- Cover all exposed skin: wear a hat, mittens and a scarf, neck tube or face mask.
- Keep active.

 WARNING LEVEL**


-48 to -54

High risk: exposed skin can freeze in 2 to 5 minutes*

- Check face and extremities frequently for numbness or whiteness (frostbite)
- Serious risk of hypothermia if outside for long periods

- Be careful. Dress very warmly in layers of clothing, with an outer layer that is wind-resistant.
- Cover all exposed skin: wear a hat, mittens and a scarf, neck tube or face mask.
- Be ready to cut short or cancel outdoor activities.
- Keep active. 



-55 and colder

High risk: exposed skin can freeze in less than 2 minutes DANGER!
- Outdoor conditions are hazardous

 - Stay indoors. 


Riding a bicycle, -9 Deg C windchill is when the ambient is -2 Deg C and the cyclist is travelling at 12 mph.
In the UK, we sometimes get into the -10 to -15 Windchill region.


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