Tuesday, January 8, 2013

Wind chill, warm hands and telemagenta Speed Machines.

Reckless abandon


Let's talk about wind chill.  When you ride a bike, you create wind and, on a cold day, that results in wind chill, which means immobile hands and numb feet.

It's January.  You're stir crazy.  It's cold but the roads are clear and dry.  And you're thoroughly jazzed about the new telemagenta HP Velotechnik Speed Machine you bought yourself for [insert your winter gift-giving holiday here] from New York City Recumbent Supply :-).

You put on your coat and hat and gloves and head out for an early morning ride to Nyack.  Eventually, the day's high will be 25 degrees fahrenheit but it's 15 deg. F when you hit the George Washington Bridge at 7am.  You warm your fingers in your arm pits, first the right hand in the left arm pit, then the left hand in the right pit.  At this point you're still impressed with yourself; it's amazing what you'll do for a muffin.

Let's pretend there's no west wind, and no runners or walkers or slow cyclists weaving all over the place, so you're making time, hitting 20 mph up the west side bikeway to the bridge.  With the chill and your early morning start, you're feeling fast, and hardcore and, frankly, a tiny bit cold.  Well, no wonder.  That 15 deg. F temperature with a headwind of 20 mph results in a wind chill of -2 deg. F.

You're wearing warm clothes, of course.  On the way there, as you ride up the hills of Henry Hudson Dr., you're slowing to a very bent-like 5 mph (15 F at 5 mph = 7 deg. F wind chill).  You get warm, even a bit sweaty.  That's bad.  Moisture compromises your insulating layers.  And you really don't want sweat freezing on your face, but it's too late to stop sweating now.

As you ride towards State Line, you hit some good downhills.  This is the fun part.  Usually.  How fast does this Speed Machine go?  Who cares what Robert said about staying within safe speeds.  It's your bike now and you decide to push it.  40...45...50 mph.  Cool?  More than.  It's frigid.  15 F at 50 mph = -10 deg. wind chill.  The thrill only lasts a minute and that's a good thing because now you're really frickin' cold.  You can barely move your hands, you can't feel your feet, and your most prized possession (not the bike) has shrinkaged to the point that it's inside out.  The women's equivalent, whatever it is, is doing the women's equivalent, whatever that is, probably something a lot more sensible.

You begin to wish you were in a car.  Or maybe not.  At the bare minimum you begin to wish you had a fairing and a pair of windproof underwear.  But for now you'll settle for a scone and hot chocolate in Piermont.  Eventually, you warm up.  You go back outside and start riding back, stopping at the police station and again at the ferry terminal to warm up.  This is beginning to sort of suck.  You can hardly wait to brag about your misery on Facebook.

How could you have dressed for this?  Do you dress for the 15 F temps when you first walk out the door?  The -2 F wind chill of your cruising speed?  The -10 degrees that freeze your fingers beyond any chance of rewarming as you ride?  Or the 7 deg. temps so you don't sweat on the hills?  Isn't the idea that you get warmer as you move?

Some people say layers and lots of zippers so you can vent as you get hot.  I tend to believe in vapor barriers which at least prevent sweat from compromising your insulating layers.  Winter backpackers have told me they wear windproof layers over bare legs.

Currently, this is what I'm trying (without using a fairing).  Wearing windproof layers, like rain gear, I dress for the wind chill I predict I'll experience most of the time with the ability to vent as much as possible as my activity generates warmth.  Zippers must be operable with one hand.  Controlling how the wind flows across my skin is key to staying warm or cool, so a ventable outer windproof layer is important.

Then, since my feet and hands are so vulnerable to wind chill on a recumbent, I try to keep them as warm as possible under the theory that, generally speaking, they can never be too warm (at least not for me).  I do everything I can to windproof them.  On my feet the first layer is a vapor barrier, then warm socks (or neoprene socks), then insulated winter boots.  If it's not too horribly cold, I'm okay with neoprene socks and bike shoes but, generally, I give up on comfortably* using clipless pedals till the warmer weather.  (*I'll go out and uncomfortably ride with cold feet for an hour or so with clipless pedals, but not much more than that.  I'd like to preserve the nerves in my feet.)

On my hands, I'm currently doing this if it's very cold.  First layer, vapor barrier.  (I use cheap latex gloves till they tear.)  Then 3mm neoprene glacier gloves.  Then windproof/waterproof shell mittens.  I'm trying to maintain a layer of dry insulating air between each layer of clothing.  I was disappointed to discover that glacier gloves alone were not good enough (for me) at windchills of about 17 F.  Adding the shell mittens made a huge difference.

If it's a bit warmer and I want some dexterity, for example so I can handle a bike lock and key, I'll start with the latex glove vapor barriers, then add glove liners, and then a pair of Outdoor Research Storm Tracker gloves.  I wouldn't hesitate to put a shell mitten over this.  The advantage to this is I can remove the bulkier layers without exposing my hands for even a moment to cold air and the cold metal of the lock.

I have a metal watch.  I remove it on cold days because it conducts the cold directly to my skin.  When I do wear it, I've noticed that my watch hand gets colder than my non-watch hand.  If I feel I must wear a watch, I'll wear it on top of a base layer.  This also makes it easier to look at.

Any metal on the bike will make you cold, so it also helps to cover the metal brake levers with insulating tape.  An extra layer of handlebar tape or neoprene or foam around the handlebar grips will help a lot too.

Getting deeper into wind chill.

What is Wind Chill Temperature?
It is the temperature it “feels like” outside and is based on the rate of heat loss from exposed skin caused by the effects of wind and cold. As the wind increases, the body is cooled at a faster rate causing the skin temperature to drop. Wind Chill does not impact inanimate objects like car radiators and exposed water pipes, because these objects cannot cool below the actual air temperature.

On November 1, 2001, the National Weather Service implemented a new Wind Chill Temperature (WCT) index for the 2001/2002 winter season, designed to more accurately calculate how cold air feels on human skin. The former index used by the United States and Canada was based on 1945 research of Antarctic explorers Siple and Passel. They measured the cooling rate of water in a container hanging from a tall pole outside. A container of water will freeze faster than flesh. As a result, the previous wind chill index underestimated the time to freezing and overestimated the chilling effect of the wind. The new index is based on heat loss from exposed skin and was tested on human subjects.

For the first time, the new Wind Chill Chart includes a frostbite indicator, showing the points where temperature, wind speed and exposure time will produce frostbite on humans. The chart above includes three shaded areas of frostbite danger. Each shaded area shows how long (30,10 and 5 minutes) a person can be exposed before frostbite develops. For example, a temperature of 0°F and a wind speed of 15 mph will produce a wind chill temperature of -19°F. Under these conditions, exposed skin can freeze in 30 minutes.

The NWS will inform you when Wind Chill conditions reach critical thresholds. A Wind Chill Warning is issued when wind chill temperatures are life threatening. A Wind Chill Advisory is issued when wind chill
temperatures are potentially hazardous.

What is Frostbite?
Frostbite is an injury to the body caused by freezing body tissue. The most susceptible parts of the body are the extremities such as fingers, toes, ear lobes, or the tip of the nose Symptoms include a loss of feeling in the extremity and a white or pale appearance. Medical attention is needed immediately for frostbite. The area should be SLOWLY re-warmed.

What is Hypothermia?
Hypothermia is abnormally low body temperature (below 95 degrees Fahrenheit). Warning signs include uncontrollable shivering, memory loss, disorientation, incoherence, slurred speech, drowsiness, and apparent exhaustion. Medical attention is needed immediately. If it is not available, begin warming the body SLOWLY.

Tips on how to dress during cold weather.
- Wear layers of loose-fitting, lightweight, warm clothing. Trapped air between the layers will insulate you. Outer garments should be tightly woven, water repellent, and hooded.
- Wear a hat, because 40% of your body heat can be lost from your head.
- Cover your mouth to protect your lungs from extreme cold.
- Mittens, snug at the wrist, are better than gloves.
- Try to stay dry and out of the wind.
- Keep your face dry, especially around the nose and mouth.
- Remove metal objects from your body, such as watches, bracelets, jewelry. Metal conducts cold onto and into your skin.

National Weather Service Wind Chill web page

Environment Canada’s Wind Chill web page

[Source: National Weather Service (U.S.A.)]

Have fun and stay warm,
Robert Matson
New York City Recumbent Supply
The Innovation Works, Inc.
copyright 2012 Robert Matson

1 comment:

  1. Nice article, it remind me that riding in cold weather shouldn't be taken lightly.