From the Snow Up
While almost any bike will do for ICEBIKING, what would the ideal bike be, if we could
design one from the snow up?
Much speculation about would constitute an ideal design for snow and ice conditions has
occurred in discussions with other winter cyclists. Some of these ideas include
attempts at flotation (wide - really wide) tires to attempt to stay on top of snow,
if not all snow, then at least the more packed variety. Also high on the list of
desired items is a fool proof and freeze proof power train, better brakes, and pedals that
can accommodate a variety of different boot styles.
Tires and Wheels
Wider tires and rims are becoming more available in commercial sizes (mostly mountain
bike, but also some street bike sizes). On packed snow trails, or other conditions
where the surface is quite hard staying on top can be practical with currently available
tires.
No one really expects to achieve floatation on all snow conditions. However, many
would like to extend the envelope a bit and be able to stay on top of wind-packed snow, or
the freeze-thaw crust that can form on wide expanses of snow such as on lakes or rivers.
Snowmobile trails provide access to areas nor normally available to cyclists. These
can be lightly packed after the passage of one or two snowmachines, and as hard as ice
after a week or two of constant traffic. In between, they can still be miserable to
ride with normal bike wheels.
Some attempts have been made to design a bike that can handle
these conditions. Hanebrink Cycles has been designing what are billed as "snow
bikes" for some time. Recently Hanebrink has been working with the Art
Institute of Pittsburgh on the design of a bike for the Antarctic research station at
Mcmurdo sound.The students there have a web page about the project located here. Press accounts of their
efforts to date are available here.
The wide tires seen here on this Hanebrink model are an attempt to extend the range of
snow conditions that can be handled.. While they will not provide flotation over a
field of undisturbed snow, they will keep you from digging in or washing out on snowmobile
trails and over thinly covered rivers and lakes. These bikes, prototypes really,
cost around $3000 and are not yet in wide-scale production. See
Hanebrink's Website.
 Even while remaining with the more
traditional diamond frame, there are significant improvements that can be made to wheels
to provide better service in winter. A full discussion appears on our "Wide Rims" page.
Replacement of rims with very wide rims, use of extremely low pressure tires and Disk
Brakes (see below) work to eliminate many of the problems associated with traditional
equipment in winter conditions.
Click the image at right for a detailed image of the Custom Snow Cat Rim, Disk brake
and asymmetrical laceing on this specialized winter trail bike from Fairbanks Alaska..
Power Trains
 Power trains on ICEBIKES have been problematic.
Several winter cyclists report good results using internal geared rear hubs. This
allows a bike to be built with out a rear derailer.
The hub at right by Shimano and the
similar models by Sturmey
Archer provide 5 to 7 speeds (higher number of speeds may be available soon) have the
advantage of lower maintenance, and some have indicated, less probability of freeze-up in
the slushy weather.
 Rohloff
in Germany manufactures a 14 speed unit which would give you a full
range of gears with no front derailleur to worry about. See
their web site.
Click the image at right to show a more detailed image on Rohloff's web
site. These unit are built for raceing and can handle the stress of heavy
acceleration. Gearing charts available on their site. Weight
is only about 200 grams more than a high-end derailleur equipped bike.
(Note: The two hubs pictured here are not to scale).
It has been said that the really cold weather performance of these models can leave a lot to be desired.
Internal resistance can increase dramatically at really cold temperatures. If
intended for cold weather use, manufacturers may be able to recommend
lighter weight lubrication.
However, at typical ICEBIKING temps the resistance is generally not too bad if the bike is
not left out over night, as a warm hub tends to stay free moving by virtue of being
ridden. These newer hubs approach, but do not yet equal the efficiency of the
derailer with regard to drive train induced friction.
The other advantage of the internally geared hub is the ability to
install a totally enclosed chain line. Once you are free of derailleur
(front and rear) there are no lateral movements to the chain. This makes
enclosure possible. Enclosures eliminate road grit accumulation and reduce
maintenance needs.
Braking
 The internal geared hubs typically do include a hub-brake,
which can eliminate another winter problem. Rim brakes can freeze in wet weather, or
in slushy snow. Extended periods of braking can warm your rims enough so that they
will melt snow and this leads to poor braking. Worse, if they are allowed to freeze
again you will have a thin layer of ice on the rims making for really hair-raising
braking. This can be overcome by simply dragging the brakes for a while, or solved
by use of disk brakes or hub brakes.
 Disk Brakes are finding favor with many off-road
ICEBIKERS. Usually hydraulically operated, these do carry a small weight penalty and
impose some constraints on frame design, and complicate wheel building. However,
they do provide excellent braking, and eliminate the icing problems of rim brakes.
The brakes pictured here are by Hope, but there are other manufacturers as well such as Magura making
similar models.
Custom Construction
So if we were to combine all of these things in a new design from scratch, would we
have a suitable winter bicycle? Probably not. Or, at least, not for most
conditions, but perhaps suitable for specific terrain. On-road use of very wide
tires would slow you down considerably.
Internally geared hubs, on the other hand excel in the gritty wet on-road environment.
The don't remove the requirement for chain maintenance, but the static chain line
allows closer fitting of fenders.
However for trails and off-road areas the Hanebrink design holds promise. It does
not appear to be a fast bike, but the additional areas opened up, especially in
snow-mobile country, may make this sort of bike a desirable addition to your stable.
In summer it could be used for beach riding and other areas where soft sand
challenges traditional bikes.
Lights
 A custom bike might require a custom bike light, one that can keep
going as long as you have the energy. Although not the brightest of lights, or the
widest of beams, hub generators may be just the solution for long-distance ICEBIKING in
the dark months.
Unaffected by cold, and with no run-time limitations the hub generator is always ready
to go. There is a slight drag penalty, even when the hub is not generating power,
(about 2 watts, cyclists normally are capable of sustaining around 100 watts, with surge
capacity to 150 watts), not something you will notice. When generating power, the
drag increases to about 8 watts.
Fully enclosed, and weather tight, these generators do not rub on your tire like the
old style generators. They weigh a hefty 610 grams. Subtract about 140 grams
for the regular front hub they replace, then subtract a pound of batteries (450 grams) and
you are within 20 grams of parity.
The down side: Light output is not what you would expect from a 30 watt battery
unit. Neither in intensity or coverage. Plenty good enough for road cycling,
you would probably not want to tackle any single track at night due principally to the
narrow beam. On a white expanse of snow this may not be a problem.
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