Understanding the weather...

[rosscbrown]

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...

 

[gbb]

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.

 

[jimboalee]

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

 

[byegad]

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.

 

[asterix]

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!)

 

[Norm]

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

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.

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.

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.

Lightening 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.

 

[jimboalee]

FL = 0.5 * Q * Cd * A * V^2

Sorry Admin.

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

 

[Norm]

FL = 0.5 * Q * Cd * A * V^2

Sorry Admin.

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

 

[summerdays]

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.

 

[jimboalee]

BTW

FL is Force luft in Newtons.

 

[Norm]

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.

 

[HJ]

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...

 

[Lien Sdrawde]

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

 

[jimboalee]

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

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!

 

[Firestorm]

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