Step 1: A Brief History/physics/textiles Lesson

Before going into how to keep yourself nice and toasty while riding through the frightful weather outside, a quick diversion into what you need to stay warm in high wind.

Normally clothes keep you warm by trapping an insulating layer of air next to your skin- this is why many layers are better for warmth and the best undergarments (thermals or old-fashioned string vests etc) are actually mostly made of air. In windy conditions (for instance, sitting on a bike at 55mph), the wind blows straight through your clothes and removes this insulating layer, which is why you don't see many Harley owners wearing cardigans.

For warmth in cold and windy conditions, therefore, the best combination is an insulating under layer with a windproof layer over the top. Think about early aviators wearing sheepskin-lined leather jackets, or arctic-dwelling peoples wearing furs with the fur on the inside. Insulation underneath, windproof layer on top will be a recurring theme in this Instructable.

Step 2: Hot Headed

The head:

On a motorbike this isn't much of an issue for me as my head is entirely encased in a windproof and insulating full face helmet, but cyclists need to consider their headwear carefully- a large proportion of the body's heat is lost through the head, but it is often the least clothed part. A simple beanie hat does wonders, with a scarf over the lower part of the face. If you tend toward black headwear like myself, the fact that you are riding a bicycle should allay any fears that you might be a terrorist.

Note: each of the clothing options described in this Instructable will be rated for cost, weather-resistance and looking stupid on a completely unscientific and wholly subjective 1-5 scale, with 5 being the preferred end of the scale (cheap, weatherproof and not stupid looking)

Motorbike helmet:
Cost: **
Weather resistance: *****
Looking stupid: *****

Hat:
Cost: *****
Weather resistance: **
Looking stupid: ****

Beanie hat and scarf:
Cost: ****
Weather resistance: ***
Looking stupid: ***

Step 3: Necking

The neck area requires specific attention, because it's the hardest join to overlap the clothes at. However, a simple scarf or tube-scarf from the market will sort out this area so it's not a great expenditure. Beware of bike shops- they will try to sell you space-age NASA-developed thermal wear with triple-layer hollow fibre insulation, when you can get a simple fleece tube scarf for much less that does the job almost as well.

There are plenty of Instructables on how to make or knit your own scarf, so I won't repeat all of their words. An even simpler solution exists: if you wear a hoodie underneath another layer, you can wear the hood down (they aren't great for keeping your head warm, a hat is better and doesn't funnel cold air down the back of your neck) and bunch it around your neck to act as a scarf. A large paperclip or bulldog clip to keep it together at the front will increase the effectiveness at the cost of looking considerably more weird.

Scarf:
Cost: ****
Weather resistance: ****
Looking stupid: ****

Bunched up hood:
Cost: *****
Weather resistance: ***
Looking stupid: ***

Step 4: Body

The upper body is probably the most important part to clothe well, but also the part where you are most likely to already own suitable clothing. As a biker, I splashed out for an armoured waterproof winter jacket and inherited a hiking jacket for cycling which between them take care of the problem, but there are cheaper options.

Almost anyone who lives outside the tropics will probably already own a warm top layer, and if you don't they aren't difficult to obtain. For an outer layer, a leather jacket is traditional and works very well, but with a suitably warm layer underneath it a simple waterproof anorak/cagoule will do- this provides the windproof layer to keep the cold out of your nice warm insulating layer. Simple.

Motorbike jacket:
Cost: *
Weather resistance: *****
Looking stupid: *****

Leather jacket:
Cost: **
Weather resistance: ****
Looking stupid: ****

Anorak:
Cost: ****
Weather resistance: ****
Looking stupid: **

Step 5: You Need Hands

Again, as a motorcyclist I splashed out for armoured gloves because one broken knuckle is quite enough for me. However, they proved to not live up to their "winter" name by being freezing cold as soon as I rode to Cambridge at 50mph on a chilly morning. This occasion was probably the height of my winter clothing improvisational powers, by the necessity of getting there with all my fingers still attached. The problem of keeping my hands warm while cycling (so requiring dexterity to change gears but cold/wind/rain resistance) confounded me for a long time.

The problem with the misleadingly named "winter" gloves I bought was that the waterproof semipermeable layer is inside the insulation, so at any significant speed the insulation becomes more or less useless. However, as the gloves themselves are quite roomy I rectified this by buying the smallest, snuggest pair of gloves I could find (specifically, ladies 1% spandex thermal gloves) and wearing them underneath the bike gloves. This provided the magical insulation-inside-windproof layers needed.

The other alternative is to add a waterproof layer outside of the gloves, which I achieved with disposable latex gloves. Yep, the sort dentists and mechanics wear. They look seven kinds of ridiculous but work frighteningly well over the top of a pair of warm gloves at keeping the winter out. They aren't great for breathability, so might not be the best for long bike rides, though. Also, if you want to maintain a slight modicum of inconspicuousness, I suggest the translucent gloves rather than bright yellow marigolds with faux-fur cuffs, but hey- to each his own.

Proper winter gloves:
Cost: **
Weather resistance: *****
Looking stupid: *****

Thermals underneath bike gloves:
Cost: ***
Weather resistance: *****
Looking stupid: *****

Rubber gloves over normal gloves:
Cost: *****
Weather resistance: *****
Looking stupid: -

Yes, I just created a special zero-star category for that last option- but if you're blasting past bored commuters you are never going to see again at a relative speed of 115 mph, who cares how stupid they look?

Step 6: Legs

Handy hint: when looking for inspiration for a pithy pun for your step title involving warm legs, do not google "hot legs".

The trousers are the most DIY part of this ensemble. Being way too tight-fisted to pay for proper bike trousers, I instead bought some waterproofs for �2 from the nearest Oxfam shop after the first time I had to ride home in the rain. These are acceptable in warmer weather, but in the cold they don't provide much thermal protection and I found the fronts of my legs getting bitterly cold on long rides.

The inspiration came on picking up an old fleece scarf and noticing that it was almost exactly twice as long as one of my legs (or, to put it another way, as long as both of my legs put together). A trial run involving sticking the scarf down the front of my waterproofs for a ride home on a below-freezing night showed the principle worked, so I decided to sacrifice the scarf to the cause (again, a replacement would be �3 from the market so I'm now down the princely sum of a fiver).

Acquire a pair of waterproof overtrousers and a long scarf from whatever source seems appropriate. Ensure that the scarf is long enough to cover the majority of the fronts of both legs. FInd the middle of the scarf, and either cut in half, or cut a small section out of the middle (I'll come back to this) leaving two equal long parts either side. (Pic 1)

Sit on the arm of the nearest armchair or something that approximates the riding position of your bike and determine the portion of the leg you would like to cover- I went from about bottom-of-trouser-pocket to ankle height. Pinch this part, take off the waterproofs and turn them inside out. Duct tape the scarf segments to the chosen part of the inside of your trousers, making sure to keep them as flat as possible to avoid a wonky seam. (Pic 2) The tape doesn't stick very hard to fabric so you can reposition the scarf on the tape, but it does stick well to the trousers. I was running out of tape so only taped a few strategic points but a complete seam might work better.

Optional: turn the trousers over and attach the extra section of scarf to the "seat" region. I decided to do this after coming out of work one evening to find that a heavy frost had fallen and my bike seat was covered in ice- next time you hear someone talk about "freezing their nads off", that actually happened to me. If you can park your mount inside then this might not be an issue- YYMV.

Step 7: And Finally

I find my feet aren't a problem when biking in the cold much. Your feet don't present a large frontal area, have a good drag coefficient and tend to be encased in a semi-solid garment anyway. Being an outdoorsy type I habitually wear walking boots which work fine with a decent pair of socks, or alternatively skate shoes which provide plenty of padding to insulate the feet.

A decent pair of shoes are a must for motorbike owners (I don't want to think about what would happen to my ankle bones in a crash if I wasn't wearing decent shoes), and boots are recommended, but for the cyclists it's pretty much just a case of staying away from well-ventilated shoes like trainers or flip-flops and wearing something a little more substantial.

Motorbike boots:
Cost: **
Weather resistance: *****
Looking stupid: ****

Walking boots:
Cost: ****
Weather resistance: ***
Looking stupid: ****

Step 8: Epilogue

I'm sure I am going to get a lot of comments to the effect of "this totally wouldn't work in Stavanger/Nunavut/Murmansk/Reykjavik/Tibet/Antarctica, you need uber thermal underwear and Goretex sock liners and NASA-developed hollow fibre everything to not freeze to death".

If you live in any of those places or somewhere with a serious winter, and intend to keep cycling in -40 temperatures and not get frostbite, you will probably need more serious clothing than I have described. I, however, live in London. It gets a bit chilly here, dips a handful of degrees below freezing and rains a lot- in those conditions, what I have described is perfectly good enough for short or medium length bike journeys, and I expect serious cyclists will probably have their own adverse weather gear anyway. If you can get away with waterproof trousers with a scarf duct-taped to the inside then great, but if you need the space-age winter clothes buy the space-age winter clothes. And with that we come to...

The Disclaimer
These clothes, while snug and warm in slightly adverse conditions, are not intended for use in extreme environments. If you try to cycle to the north pole wearing only clothes that you bought at Oxfam and subsequently get frostbite, I disclaim any responsibility.