The secret part of the WP ACS air shock is not the shock
itself, but the regulator hidden inside the airbox.
The ACS is a conventional WP shock, albeit with an air
spring. The regulator keeps the air pressure consistent.
Forget Showa Triple Chamber forks, the WP AER forks have a
volume knob that goes to 11 (and four Schrader valves).
with air suspension front and rear, and his effort was so
low-key that virtually no one outside of the Pro circus
knew much about what he was riding.
So, when WP Factory Services called and asked MXA if
we’d be interested in riding Andrew’s BTO race bike, we
immediately jumped at the chance to jump jumps with
WP’s super-secret works suspension. But, WP is very
secretive about Short’s suspension components. Even
though they offered us the bike, and WP’s Kyle Guglielmetti
and Chris Brody came with it, getting them to tell us any
details was like pulling teeth. We’d ask a question,
and they would mumble something. We would ask for
clarification on what they didn’t say, and they would look
at each other as if waiting to decide if they should speak.
We’d pressure them more, and they would finally reveal a
tiny tidbit of information, normally something we already
knew. It made no sense. WP had invited us to ride the
bike, yet they weren’t going to tell us anything about it.
We told them that perhaps we should all just go home.
Finally, they agreed to tell us a few of the ins and outs
of WP’s AER and ACS air suspension, but they left a lot
to our imaginations.
WHAT YOU NEED TO KNOW ABOUT WP
AER AIR FORKS
(1) The forks on Andrew Short’s bike are not the forks
that come on the 2016 European KTMs or are planned
for the 2017 KTMs and Husqvarnas. They are single
air-chamber 48mm forks. Short’s forks have massive
52mm fork legs and quadruple air chambers. When the
production KTMs get the 48mm AER forks in 2017, they
will have one Schrader valve on the fork cap and a unique
bleed hole that siphons off air pressure to act as a balance
spring. They are creative but not related in any way to
Short’s works forks.
( 2) Similar to Showa TAC forks, which have three air
chambers, the WP AER forks have four air chambers.
Three of them are compression chambers and one is a
balance chamber. The three air-compression chambers
have separate functions, with the main chamber holding
approximately 170 psi, depending on track conditions and
rider weight. The other two chambers run less air pressure.
The goal is for the three compression chambers to provide
as linear a feel as possible as the pressures collapse into
each other in succession. The fourth chamber is the
balance chamber, which works in opposition to the three
compression chambers to eliminate topping out. The
tuning possibilities of three separate air pressures allows
the WP AER fork to be plush yet stiff at the same time.
The main chamber, the one with the highest air pressure,
is an enclosed cartridge, so the oil to lubricate the inner
workings and control air volume in the other chambers
is not used in the main chamber.
( 3) There are 25 clicks of compression damping on the
right fork cap and 30 clicks of rebound on the bottom of
the right leg. The air is in the left leg only. The damping
system inside the 52mm AER forks is not that different
from the one in the works Cone Valve forks that Ryan
Dungey and Marvin Musquin use, except that they have
coil springs in their forks.
( 4) Because the 52mm air forks do not have coil springs
in both legs, they weigh more than 5 pounds less than the
steel-sprung forks on Dungey’s bike.
( 5) The BTO team sets Andrew Short’s AER forks up so
that they will bottom if pushed to their limits. The WP
technicians are rightfully proud of how hard they work to
get full travel without any clank.
( 6) The triple clamps are 22mm offset Neken clamps,
but because of the very large stanchions needed to house
the 52mm legs, the triple clamps are specially built for the