Damping on one leg, air spring on the other.
Weighing the new fork.
The air fork is just 16.5 lbs.
A 4CS fork weighs in at 20.1 lbs.
The internals of the air spring side are extremely simple. Air pressure is fully contained within this internal cylinder, so a leaking main seal won't cause the fork to go flat.
A close-up of the air spring piston.
A bypass groove separates positive and negative air chambers. This very simple design was borrowed from mountain bike suspension.
There is no need to disassemble the jam nut assembly at the end of the damper rod. This makes it easier to assemble and disassemble the fork for service.
The white plastic piece is an oil lock collar, part of the new fork's bottoming control system.
If the fork cap on the damping side looks familiar, it's because it is. The cap is identical to the discontinued WP closed cartridge (bladder) fork.
This is the cartridge pressurization system. It uses a spring and floating piston like the WP Cone Valve and many KYB and Showa forks.
The AER 48 uses an assembly groove to allow excess oil to escape during assembly, just like most Japanese forks.
The base valve has a thick stack of .10 shims.
This unique base valve refill check system does away with the standard check spring. The shim with the sculpted interior flexes freely enough to function as a check valve all by itself.
The base valve piston is thin and wide at 34mm in diameter.
The mid-valve piston is massive at 34mm, the same diameter as the base valve.
This fork came from the factory with zero mid-valve float, and it looks like there is no way to add float without the use of non-OEM parts.
The rebound tap is straight 6mm OD.
300 psi shock pump. Get used to carrying one of these.