Winter Wisdom: Know Your Snow!

A great day for a bike ride!

Intro

In this instalment of Winter Wisdom I will be going over different types of snow and ice.  Knowing what you are in for is the difference between enjoying a ride and eating a face full of snow.

Please note that this is specific to my experiences in Ontario; you may experience different winter conditions depending on where you live.

Powder snow with fresh tracks.

Types of Snow
They say no two snowflakes are alike.  But some are definitely more different than others.  When you start winter cycling you learn to identify different types of snow because it directly impacts your handling.

In general fat tires can float on top of it and narrow tires can cut through shallow snow. But it's not always that straightforward. Below are several types of snow and some general recommendations.

Powder
It's light, fluffy and usually has fallen recently.  If it is shallow it can be fun to cut through on a bicycle.  The deeper it gets, the more difficult it can be to pedal through.  Once it's about mid-calf it interferes with your pedals and becomes impossible to cycle through.  Having a fat tire enables you to float and you won't sink as deeply, which means you can handle deeper snow.  But even fat tires have their limits.

Snirt and road grit covering packed snow.

Packed
Snow that has been compressed by snow plows and vehicular traffic.  It is very dense and can be almost as hard as ice.  It can also be as slippery, especially if covered with a light layer of powder or snirt. Knobby tires and studs give great traction on this sort of snow.

Packing

Multi-layered crust.  The broken top layer makes it difficult

to continue with regular width mountain bike tires.

Think of snow that is perfect for snowballs; sticky and near it's melting point.  The closer it is to its melting point, the heavier it is. It can be cut through with narrow tires when it is shallow.  Knobby tires can provide good traction at various levels and densities of packing snow.  Fat tires can provide flotation on packing snow.

Crust
When the top layer of snow is stronger than the layer(s) below it. This is caused by the top layer partially melting during the day and then re-freezing when the temperature drops again, usually at night.   If a crust can hold the weight of a human it is considered to be "Supportable." If it cannot it is considered to be "Breakable." It is very possible to have a crust that is supportable when you are on foot but breakable when you are riding it on your bicycle. Studded or Knobby tires help with riding on supportable snow whereas breakable snow is extremely difficult to bike through.  Fat tires may be more supportable than skinnier tires but may also run into issues if the crust is very icy.

Slush

Made up of partially melted snow but more watery than packing snow.  Slush is formed when prevailing conditions begin to warm, or on road as a result of being heated and mixed by traffic.  Slush isn't very slippery on its own but contributes to decreased traction when coupled with ice or packed snow below it.  Its watery nature can be hazardous to a rider without fenders or mudguards.

Snirt

Snirt

This compound word describes what happens when snow is mixed with dirt, usually from plowing or from motorized traffic stirring up snow. It is brown to maple in colour. Snirt can be very slippery on it's own but becomes more treacherous on packed snow and ice.

Crust surrounded by powder snow.

Types of Ice

One very iced over bridge!

On paved roads, ice is usually formed from melting and re-freezing or from precipitation or other weather conditions.  In off road conditions ice is encountered commonly as a frozen body of water, such as a lake, river, pond, creek, et cetera.  Ice is extremely slick and dangerous.  Studded tires are usually advised for icy conditions.  Below are some specific subsets of ice to keep an eye out for.

Black Ice
A very thin layer of ice that is thin and transparent.  When formed on black asphalt it is nearly invisible, hence the name.  It can be dangerous if you ride on it unaware; studded tires handle black ice effectively.

Glaze ice
Usually a result of freezing rain, it literally glazes everything.  Road patches, other kinds of ice and snow and any part of the terrain will be coated.  Watch out for nearby trees; if they are coated as well they can be hazardous if they fall.

Pellets
Round small pellets of ice that either precipitate in that form or are formed from thawing and freezing.  This ice can be treacherous as it can vary in slipperiness and sinking can be common where it is deep.  There's no specific tire that is great for ice pellets; one patch might be great for fat tires and the next patch will give an advantage to knobby tires.  Approach with caution!

Spray Ice
This is formed near large bodies of water such as rivers which haven't frozen over.  Currents, depth and width all play a factor in a river not freezing.  But spray from the river will freeze very quickly. In a windy winter storm, crossing a bridge can feel a lot like being sandblasted by these particles. Bridges and adjacent roads

A pathway covered in frost.

Frost
When temperatures reach below freezing, frost can form.  It usually coats the ground with a very thin layer of ice crystals.  Soft rubber winter tires can  easily handle frost.  Normal tires can usually proceed fine in a straight line; some caution is required when handling in corners.

Conclusion
Getting to know snow and ice has definitely made my winter cycling experience a more enjoyable one.  Knowing what is on the ground and how my tires perform help me select routes where they will excel; it also enables me to avoid paths that will be a complete suckfest.

Your mileage may vary, pun intended!  There are many types of snow and ice not discussed here, such as glacial ice, firn, penitentes, watermelon snow and many others.  Hopefully this post gives you a head start; but there is no substitute for experience.  Get out there and ride!