54 • GARAGE BUILD • ISSUE 419
Suspension travel is another thing
that must be measured before lowering
a bike. Front suspension travel can be
measured by securely placing a zip-tie
around one of the fork tubes as shown
in the photo. Go for a ride. Measure
how far the zip-tie has moved. That’s
the movement in the forks. The mea-
surement on my bike is almost 3 1/2". If
I were to lower the front end with dif-
ferent fork springs and spacers, I would
come perilously close to bottoming out
the forks during severe braking.
Measuring rear tire clearance is a
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container of children’s modeling clay
and a length of clear food storage
wrap. Roll the modeling clay into a ball
and press it against the center of the
rear tire tread. Poke a small hole in the
food storage wrap and place it over the
modeling clay with the hole lined up
over the center of the tread. The food
storage wrap holds the clay in place
when you roll the bike just far enough
to position the clay directly over the
axle. Now get on the bike, lift it off the
sidestand and bounce up and down to
compress the clay. If you often ride
with a passenger, get your passenger
bouncing up and down on the pillion
pad. Roll the bike back to expose the
squashed clay. Put the sidestand down
and poke your depth gauge through
the hole in the food storage wrap to
measure the approximate clearance.
The measurement shown in the
photo was taken with the adjustable
shock absorbers on my bike set to the
middle of their adjustment range. I’ve
learned not to set it lower because
the rear suspension will bottom out
when I encounter bumpy roads and
the diameter of the tire grows larger
slightly at highway speeds due to
centrifugal force.
There are a number of things to
plan for before you decide to lower a
bike. Don’t start the project with un-
realistic expectations. How much can
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shouldn’t? Will suspension changes
make the bike handle better or worse?
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if the results are unsatisfactory?
Aftermarket catalogs and manufac-
turer’s websites contain many disclaim-
ers and precautions regarding lowering
kits and suspension parts. They range
from telling customers that suspension
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dling characteristics to warnings that
lowering a bike may run afoul of laws
regarding what can and can’t be used
on the street.
Some state motor vehicle codes
may state that motor vehicles (which
would include motorcycles) may not
deviate from the height and level at
which they were manufactured. This
may seem a bit extreme, but all it takes
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cars, trucks, and bikes to move elected
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in the interest of safety.
The best reason for lowering a
bike is that the rider is unable to put
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stopped. A few years ago my niece
was lamenting that she was on her
tiptoes when stopped on her Sportster- Her father suggested taller shoes.
Her friends urged her to get shorter
shock absorbers. The solution was a
thinner seat with a narrower section
at the front. Now she rides and stops
more securely. GB
Lowering the bike 3/4" with the adjustable
shock absorbers moves the bike to an angle
of 80 degrees.The swingarm angle shown here will change with the
weight of a rider and passenger.My bike makes an angle of about 76 degrees with the
adjustable shock absorbers set in the middle of their
adjustment range.
Bikes like this Ironhead Sportster should not be lowered because the chain will slice into the oil tank.