What Makes Pugsley So Weird?
It all starts with the tires.
Big, fat tires, particularly run at low pressure so they flatten out a bit,
provide more ground contact and better traction than any standard tire. It
allows the
tires to ride over the top of soft stuff. It’s the same way snowshoes work:
spread the load out over more surface area and you stay mostly on top of
the snow instead of sinking way down into it. It’s this theory that drove the
design
of the Pugsley: a bike you can actually ride not just off road but where
there is no road or trail, without tearing up the earth, without sinking into
the
snow, sand or loamy soil, and without having to get off and walk.
To accomplish this, you need big tires (and with really big tires, it helps to have really big rims too). Standard frames simply are
not designed for really big tires (anything 3.0” or larger, and most frames
don’t
even
accept tires this big) because most people, for most riding, don’t need the
float and don’t want the weight of big tires. But in certain situations,
big tires are the best way to get around. So to use really big tires, you
have to make a frame’s seat- and chain stays wider. And to keep the chain
stays as short as possible (so it handles like a bike instead of a truck;
in other words, the Pugsley is responsive and maneuverable despite it’s bulky
look), and as well to help gain chain clearance (more on this in a second),
you also need to use a wide bottom bracket. We went with the widest standard
BB out there, a 100mm shell (most bike frames use either a 68 or 73mm shell),
because our Endomorph tires are a whopping 3.7”.
Now then, you’ve made a frame capable of running really big tires, but even with
the wide BB, you’ll still have chain clearance issues. Our tires are so wide
that in terms of chain line they overlap the innermost gears. In other words,
when running in the easy gears (closest to the frame), your chain will hit
your tire. Not good.
So what to do? Well, we curved our seat and chain stays right of center, and
the wheels for the Pugsley need to be built offset to match (in other words
they’re
dished, but the opposite direction from normal). This gave us all the chain
line we needed. Rear end solved.
Which brings us to the fork. On your average fork, the crown is either as wide
as, or narrower than, the hub. In order to allow not just tire clearance, but
snow and mud clearance too, the fork for a bike such as the Pugsley would have
to be much wider at the crown than at the hub, and front hubs are narrower
than rears which amplifies this difference. Making a fork with a wide crown
with legs that pinch down at he hub works o.k., but it creates problems getting
the wheel in and out, and as the Pugsley is designed and built to be a true
adventure bike, it seemed sensible to us to design the fork spacing so it would
accept a rear hub (135mm mountain hub standard), thereby achieving good clearance
without the pinched look while allowing the front and rear wheels to be interchangeable.
This
may not seem like such a big deal, but messy conditions can wreak havoc with
your parts, particularly in extreme cold. Freewheels or freehubs that
work fine the rest of the time, for example, can fail and just spin with the
drive pawls open when it’s cold enough to freeze the grease inside, and when
you’re in the middle of the arctic at 40 degrees below zero Fahrenheit, this
sort of failure is not just annoying but quite dangerous. Having a spare operational
wheel can mean the difference between getting out under your own steam and
leaving on a Life Flight helicopter.
Now, since the frame is offset to allow chain clearance, the wheels
need to be built offset of center too (note: we offer several varieties
of Large Marge rims, and some are asymmetrically drilled specifically
for use on the Pugsley). We curved one of the fork blades to
accommodate the wider hub and offset rim. Problem solved. It may look
cartoonish, but we didn't make it that way to draw stares or to be
goofy. There is a method to our madness. Function first.