Note: Many thanks to Ed Sassler @ Harvard/Wheelworks for the following tips!

Keeping warm in the winter is really about two things: Staying warm and staying dry. Your body produces moisture in order to maintain body emperature, your cold weather clothing must be able to handle this and still work. There is a science to dressing for winter rider, once you understand the function of each layer of clothing you will be able to dress for any type of weather. Clothing can be broken down into three basic layers: The wicking layer, the insulating layer and the isolation or wind block layer. Each layer has it's job and it's place.

The wicking layer: The job of the wicking layer is to pass moisture away form your skin by capillary action. There are a few requirements for this to happen. First, moisture passes from higher concentration to lower concentration. Second, it doesn't work if there is a significant drop in temperature from the skin to the outside of the wicking layer. This means that the wicking layer is NOT an insulating layer, worn by itself it should do little to maintain body temperature. It also has a saturation point beyond which it's not going to pass moisture. The thickness of the wicking layer should be based on the amount of moisture over the whole ride. Longer rides require thicker wicking layers.

The insulating layer: It's just like the insulation on a house, R value is measured by thickness. The insulation is a layer of dead air space, if no air moves across the space no body heat is lost. Insulation has nothing to do with fashion, it's all about thickness. Stuffing more insulation into a tight fitting shell doesn't give a higher R value, in some cases it cuts down on blood circulation, making things worse.

The isolation/wind-block layer: This layer simply divides the layered system you're wearing from the outside world. The insulating layer only works if it's a true dead air space, air flow must be kept out.

Things to look for, claims to ignore: Many jackets claim to pass moisture. That would imply that wicking action works from almost 100 degrees down to zero. In the summer you see salt build-up on the outside of jerseys, you never see that on the outside of winter jackets. It's a case of confusing the jobs of the different layers. The outside layer isn't a wicking layer, just like the wicking layer doesn't need wind block - if wind block is needed on the wicking layer you need to get a new shell. The wicking layer should also not be absorbent. Some companies sell a base layer on comfort - it's not so comfortable when it's soggy and cold. Insulating layers also shouldn't be wind block. Many wind blocking layers have the initial feel of being warmer, but the wicking effect of the layer under them stops working, this the "clammy" feel. Each layer has its job, each job must be done in the right order.

Making layers cost effective: I go with the thick/thin scenario. For the insulating layer I have both a thick layer and a thin layer. If it's not too cold I'll throw on the thin layer. If it's too cold for the thin layer I'll put on the thick layer. If it's really cold I'll wear both. This works for the wicking layer as well, but it's a function of time, not temperature. Assuming I get the insulating layer right, I'll wear my thin wicking layer for shorter rides, my thick wicking layer for longer rides and both if I'm going to be out all day.

Feet, hands and head: Most people find they have one problem area, many find it's their feet or hands. Feet are a special problem because the shoe must still clip into the pedal. There are shoe covers called booties which can help with this problem. The bootie will act as a wind block with a certain amount of insulation based on thickness, but it's far from the whole story. The sock is the first line of defense, but being the first layer it needs to have wicking qualities, not just insulation. Many people make the mistake of stuffing a thick sock into a shoe that fits well with a thin sock. Good circulation is part of keeping warm - that tight shoe with the thick socks won't help. Outside the shoe but under the bootie is where insulation needs to be added. Find a large wool sock, make a cut-out for the cleat and use it as another layer under the bootie. Wool is the best material to use here because it retains it's insulating properties when wet.

The same tricks can be applied to gloves. There are thin glove liners sold which you can wear inside a normal pair of gloves. These liners simply extend the range of the gloves, in other words, if it's just a little too cold for a medium pair of gloves, that pair over a pair of glove liners should be fine. Glove liners can also extent the time a pair of gloves can be worn. Fingers don't give you enough room to layer, so the whole wicking/insulating/isolating idea gets dropped. The down side is that gloves get soggy after a while. A second set of glove liners is both inexpensive and easy to carry with you. Simply swap out the wet pair for a new dry pair when you stop and the gloves feel dry and warm again.

Keeping your head warm: First, there is the helmet, which has big vent holes which channel cold air. The simple solution here is getting a helmet cover which acts as a wind block and creates a dead air space over your head. Ears also need to be covered, but the material can't block sound. There are wide headbands that do the job without changing the fit of the helmet. A scarf can be used to cover the neck and add insulation to the chest. This is a key area in very cold weather because it's your lung's last line of defense. If the air you breath doesn't get warmed up on the way down, it enters you lungs below freezing and causes damage.

A word about fit: There are a few things that you want to look for in clothing. The first thing that goes on are your shorts - keep that layer the same all the time. After the shorts comes the wicking layer, then the insulating layer. Tights should not have any padding in them, that's the job of the shorts. It's a bad idea to add padding to anything that goes past your knees and is held in place at the ankles, it's just asking for the padding to be moving around all the time. Some people like bib shorts, others like draw string tights. If you're going to have a number of layers, go easy on the number of garments you own with zippers down the middle. One zipper is OK, two is starting to add up, more than two and it starts feeling like you have a metal bar down your chest. Lastly, in buying a wind blocking layer, don't be looking in the mirror asking if it makes you look fat. Tight outter layers keep the inner layers from doing their job. They need to fit well, but not compress the other layers. Shells also shouldn't be air tight, they should have vents of some sort. Many well designed shells will have non-wind blocking sections in areas that don't see direct air flow, or vents in key areas such as the back and under the arms.

Happy Riding!
The PTS Team