Gearing is the least expensive hop-up in the
sport. It can make a bad bike good.
MY FRIENDS ARE STICKS IN THE
My friends are sticks in the mud when
it comes to making gearing changes. I feel
that my 2016 KTM 350SXF doesn’t accel-
erate quick enough on the exit of corners.
It feels like it’s taking its time to get there.
Every time I ask what they think about adding a tooth to the rear sprocket, they say
that the factory did a lot of testing and the
stock gearing is best. Is it?
No offense to your friends, but unless
they are riding your bike for you, they really don’t have a say in what you do to it.
Every MXA test rider adds one tooth to the
rear of the KTM 350SXF, and some even
add two teeth. This is no secret. We have
been running this gearing since the 350SXF
was first introduced in 2011. Don’t ask your
friends, just do it. They’ll never notice, but
When air gets hot it expands, or
so they used to teach in school.
WHY DO MY AIR FORKS
I set the pressure in my air
forks before practice and then
check it before my first moto.
I notice that the air pressure
goes up a couple pounds.
How can this be? The air is
contained in a sealed chamber
and thus should stay the same
all the time. How say you?
A balloon is a sealed chamber, but a balloon’s air pressure goes up when the air
temperature gets hotter and
decreases when it cools down.
That is what makes hot-air balloons work. Your forks are just
like a hot-air balloon. There are
several factors at play here:
(1) When you set your fork’s
air pressure in the morning,
the air is typically cooler than
later in the day when your
first moto rolls around. If the
ambient temperature rises 10
degrees, your fork’s air pressure will also rise. ( 2) When
you rode practice, the forks
created friction as they went
up and down over every bump
and ripple on the track. The
friction heated up the metal,
seals and fluids in the forks—
and that heat causes the air
pressure to rise. ( 3) It is true
that if you put 150 pounds
in your forks in the morning
when it is 65 degrees outside
you would still have 150 psi
in the forks—but only when
the air temperature returns to
65 degrees. ( 4) MXA test riders set their air forks to their
desired air pressure before
practice and then check them
before the first moto (and
second moto) and reset them
back to the desired pressure
setting. As a rule of thumb,
the typical air fork will gain
about 4 pounds of pressure
during a 20-minute moto (as
will the pressure in your tires).
Left to its own devices, it will
return to the original pressure