Mid 2003 I began seeing "spy" photos of a new air shock from Progressive Suspension – the 5th Element Air.  I was immediately interested.   Based on my experience with Progressive Suspension’s 5th Element coil shocks (see part 1 & part 2 of this 3-part series) I knew I needed to get one of these for my cross country bike.   After reading a few reviews and confirming the 5th Element Air matched what I was looking for, I got one for my 2002 Specialized FSR Enduro.   While I don’t have as much time on the Air as with the coil over version of the 5th Element, I’ve been able to put on some good miles during the first half of the year and can say without reservation that the 5th Element Air lives up to the standard set by its big (coil-over) brother.

In theory, the 5th Element Air is a much simpler shock to setup than the 5th Element coil version – there are only 3 adjustments on the Air, compared to 5 (6 with preload) on the coil.   5th Element Air has an adjustable main air spring, Internal Floating Piston (IFP) air pressure adjustment, and rebound damping adjustment.

• Internal Floating Piston (IFP) – This air pressure setting controls the position sensitive damping feature of the shock, allowing adjustment of the starting compression force that controls the pedaling platform and high-speed blow-off.  The lower the IFP pressure, the softer the ride and the lower the blow-off threshold for high-speed impacts.   Higher IFP pressure provides a firm, almost locked out feeling, pedaling platform and a higher blow-off threshold for high-speed impacts. 
  
• Main Air Spring - This air pressure setting controls the sag of the shock. Quick definition – Sag is the amount the shock is compressed by the rider’s weight, and is measured when seated.  Progressive Suspension states the 5th Element Air performs best when set with 25% of the shock stroke as sag.  To determine your sag - move the included O-ring against the main seal/wiper, sit on the bike (no bouncing), and measure the distance from the seal/wiper to the O-ring.   This is your sag, and you can figure out the percent sag with the following formula:  100 / shock stroke * measured sag = percent sag.   The pressure range for the main air spring is from 75 to 150psi.
  
• Rebound Adjustment – The Rebound adjustment controls the speed the shock returns after being compressed.    Turn the adjustment clockwise to slow the rebound, counter-clockwise to speed up the rebound.   If rebound is set too fast, your bike will be too springy – causing excess pedal bob and can buck the rear end on larger hits (see early videos of Bender).   If the rebound is too slow, the rear suspension will not be able to return fast enough to take the next hit – causing the rear to firm up and lower.  

Remember, adjusting any one of the three adjustments will affect the performance of the other two adjustments.  Example, increasing the main air spring pressure will cause the shock to rebound faster, and the Rebound adjustment will need to be increased to compensate.

A good tip is to write down your air pressure settings each time you make an adjustment.   With the 5th Element coil, it is fairly easy to remember your settings as the bulk of the adjustments are made mechanically (screw).  You can visually see the setting for each adjustment, or just count the number of turns from full in or out to figure out where you are at.   With the two air adjustments on the 5th Element Air, each time you attach a shock pump, the shock pressurizes the pump so you are unable to see what your current settings are.   This is true of any air spring shock or fork, but it does make fine-tuning the air settings easier if you have a starting point to work from.

My settings (210lbs on a Specialized Enduro): 150psi in the main spring, 125psi in the IFP chamber, and rebound set at 1.5 turns out from slowest.   I prefer the firm pedal platform and run only 20% sag (to compensate for a long-travel fork).

How does the 5th Element Air ride you ask?   The best way to explain it is by comparing to a Fox Float with a lockout.   The 5th Element Air has a similar feel to a Fox Float shock that is locked-out, but actually pedals better than the locked-out Fox.   However, even with the firm locked out feel - the 5th Element Air is able to respond to the smallest of bumps!  Looking at the rear suspension on a long, steep fire road climb, the Air is motionless.   Out of the saddle sprints can overcome the pedal platform, but there isn’t much more movement than a locked out Fox Float.   The key difference between the 5th Element Air and other shocks is there is no rider adjustments required while on the trail – meaning no messing with a lockout lever. The 5th Element Air always has the firm pedal platform, not just when a level is flipped – it provides a lockout feel and is able to absorb bumps at the same time.   Very nice.

It’s worth mentioning that I didn’t really have a problem with the performance of the Fox Float on my Specialized Enduro, but after having the 5th Element coil on my DH and FR bikes, the Specialized seemed to feel sluggish and bob with each pedal stroke.   The efficiencies could all be in my head, I do feel much faster with the 5th Element Air on the Specialized Enduro.  It is crisp and seems to accelerate much faster. 

On bigger hits, the 5th Element Air is very supple.   Due to its large volume main air chamber, the shock doesn’t "ramp-up" as it progresses through its travel – it has a very coil-over like feel.   In addition to the firm pedaling platform, the Control Valve Technology (CV/t™) provides the same resistance to bottoming as the coil version – meaning it feels bottomless.   Granted I don’t do much bigger than a 2 foot drop on my XC bike, but the high-speed hits and occasional jump are taken in stride.   I’ve even ventured onto a few of the local freeride trails with my Enduro, and while still shying away from the bigger stuff, I feel much more confident in the rear suspension and have tried a few of the smaller jumps and drops without a problem.  

Another feature of the 5th Element Air worth noting is its incredible light weight   Progressive Suspension lists the 6.50 X 1.50 model at under 200 grams.  That is light!  Holding the shock in your hands is almost spooky, it feels like there is something missing.   It is about the same weight as an average flat handle bar!   I always go for reliability over light weight, but the 5th Element Air has delivered both - a very nice bonus.

The spherical ball mounting used in the shock eyelets has received mixed reviews in other publications, but I have not had a single complaint with the system.  The common statement is that the spherical ball mounting system decreases frame rigidity as the shock is no longer helps as a structural component.   My Specialized Enduro is a very well built frame, so I have not notice any decrease in frame rigidity.  And by removing the shock from the stress of side loads, fiction is reduced allowing for a smother ride and less wear on the shock.

A testament to the quality and custom feel of the shock was its packaging.  This in no way improves the performance of the shock, but first impressions mean a lot, and the packaging and packing of the shock was spot on.   The shock sticker is not applied to the shock out of the box.   At first I thought this was a bit cheap, but after thinking it through – allowing the owner to apply the shock sticker ensures that its placement is correct (you’re not stuck with an upside down sticker if your shock has to be mounted different that what the manufacture guessed).   And for the weight weenies, I’m sure there are a few grams saved by not putting the shock sticker on at all!   Another nice touch was the included shock pump - very high-quality.  The owners manual was extremely helpful and they even included an extra 5th Element sticker for my tool box.

The 5th Element Air has made an improvement in every aspect for my XC/trail bike.   It has improved my climbing, both on the long fire road climbs and the single-track climbs.  It has improved my trail riding – the firm pedal platform is always there to help me sprint out of corners and power through the rough sections efficiently.  It has improved the performance of my bike on the downhill sections – the smooth, linear progression through the travel and bottomless feel have me going faster than ever on the descents.   The shock is light, reliable, and performs better than anything on the market.   What more could you ask for?