When Andrew Short’s BTO Sports KTM bike was wheeled out of the team trailer at the 2014 Monster Energy Cup, it was unlike any other 450 SX-F in the United States thanks to the WP air fork mounted on the front-end. The European suspension company has quite the history with air components, particularly in the rear shock, but the fork was a new venture for all involved. It’s a good thing we learned more about the parts during the 2015 season from WP Racing Engineers of New Suspension Components, because somewhat similar air fork units came stock on the 2016 KTM models sold throughout Europe (WP AER 48). According to some close to the company and products, WP air forks are expected come standard in the US market sometime in the near future, but production of the air shock is unlikely.
The AirFork Development started in 2012 with first sketches and first prototypes with different concepts. In 2013 the decision for the current system was made and the development started. The AER Project was then a joint development project between WP R&D and WP Racing Department. So it’s no surprise that the AER48 and AER52 Forks share many similarities like the Safe Sealing Systems, low friction technology, the concept itself, and many other pieces that are at work in both forks. While the biggest focus next to performance on the AER48 Forks was to make it as easy to handle as possible (just one valve for example), the focus of the AER52 Forks was giving the riders a wide range of adjustability for different conditions, riding styles and tracks.
Short’s forks are slightly different than what the general public is offered, as they are a four millimeters larger (52mm compared to the production 48mm), are adjusted via multiple Schraeder valves (three on the AER 52 compared to the lone valve on the AER 48) and feature a four-chamber design: a Rebound Chamber and three compression chambers. The three compression chambers work together to get the most linear feel as possible out of the forks and give the riders plenty of possibilities to adjust to the conditions on Race day, while the rebound chamber is keeping the balance in the fork. The AER52 Forks also feature a WP Cone Valve Unit, which is completely new designed to the demands of an AirFork Damper Unit.
A few important things WP Racing Engineers mentioned to us at the start of the season were:
The parts used at the Monster Energy Cup were prototypes, with Short riding on them only a few times before the event, but plenty of dyno testing occurred before they ever went to the track. Short’s experience with testing and on other components came in handy with the new part, along with the switch to the vastly improved 2015 KTM 450 SX-F chassis. Nathan Watson also served an important role in testing, thanks to his time on the FIM Motocross World Championship with the ICE One Red Bull Husqvarna team.
The prototype forks Short used at MEC last year have been internally branded as the S.A.S.F Forks. At Anaheim 1 Short was riding the second development stage, what featured a three chamber design and have been branded as ACS Suspension. Due to Short’s injury at the New Jersey SX, the introduction of the third and latest development stage (the AER52 stage with 4 chamber design) needed to wait until round eight of this year's Nationals.
The front and rear air suspension parts on Short’s bike made it weight roughly five pounds less than teammate Justin Brayton’s BTO Sports KTM. In fact, the difference between Short’s fork and similar factory components that were complete with a titanium spring was four pounds. As one would expect, there is an even bigger weight loss when compared to stock components.