HS3 Air Spring
EXT's Storia and Arma shocks have developed a legion of loyal fans in the mountain bike world, so it only made sense for the Italian company to take the next step and develop a fork to go along with them.
The Era is the result, an air-sprung fork (a coil version is in the works) that uses EXT's HS3 hybrid air spring. There are 140, 150, 160, and 170mm options, all for 29” wheels.
My 170mm test fork weighed in at 2270 grams, including the thru-axle. Not surprisingly, high-end Italian suspension isn't cheap - the Era retails for €1480.
EXT Era Details
• Intended use: all-mountain / enduro
• Travel: 140, 150, 160, or 170mm
• Wheel size: 29"
• Stanchions: 36mm
• Offset: 44mm
• HS3 hybrid air spring system
• Adjustments: HSC, LSC, rebound, two positive air chambers
• Actual weight: 2270 grams (w/thru-axle)
• MSRP: €1480
• More info: extremeshox.com
Inside the Era's left leg reside two positive air spring chambers, a negative chamber, and a small coil spring to make the fork even more supple. Because the coil spring has less friction to overcome than the air spring before it starts moving, it helps ensure that the initial portion of the fork's travel is very responsive. DT Swiss use a similar concept in their F535 One fork, although the damper and air spring designs of the two forks are very different.
The Era's positive chambers are filled via two Shrader valves on the top of the fork marked + and ++. Personally, I think that labeling them as A & B or 1 & 2 would have been a little less confusing, but maybe that's just me. The + chamber is the larger of the two, and is responsible for the amount of force required to compress the fork through its entire stroke.
As the fork compresses, once a certain pressure is reached the piston that separates the two chambers begins to move and the ++ chamber takes over, handling the mid-stroke support and amount of bottom out resistance.
Getting the fork set up requires inflating the higher pressure ++ chamber first, and then the + chamber. The pressure that's in the ++ chamber needs to be higher than what's in the + chamber in order for everything to work properly. Damper
On the damper side, the Era has externally adjustable rebound and high- and low-speed compression damping. The exact number of clicks varies slightly due to assembly tolerances, but my test fork has a total of 12 clicks of LSC and 10 clicks of HSC.
The cartridge uses a spring-backed internal floating piston to handle the oil displacement that occurs during compression, and uses a piston that measures 22mm in diameter. EXT went with a larger piston diameter and a larger volume of oil in order to help maintain consistency on long, sustained runs. Chassis
EXT worked closely with Mojo Rising to develop a crown that met their stiffness goals. The result is manufactured from forged 7050 T6 aluminum and uses a shape that increases the amount of overlap between the crown and the steerer tube. More overlap should increase stiffness, as well as reduce the likelihood of the fork developing the dreaded 'creaky crown syndrome'.
The Era's bushing design and construction were originally created by EXT for use on World Rally Championship vehicles. They also developed their own oil, and worked with RacingBros to develop the fork's wiper seal.
The quest to create a supremely smooth operating fork didn't stop there, though; EXT also use a proprietary cartridge coating and a finishing process on the fork's steel chromed shafts to ensure there isn't any unwanted stiction.
I'm usually not one to gush, but after six solid rides on the Era I'm comfortable saying that I've never ridden a fork that felt this good right out of the box. I've even switched bikes with a couple of riding partners mid-ride so they could experience what I was feeling, and in both instances the general consensus was “that's ridiculous.”
Yes, the “air that feels like a coil” claim has been made multiple times before, but in this case EXT have come incredibly close to mimicking the ultra-sensitive, plush feel of a coil fork, with the ability to tune the end stroke ramp up to prevent harsh bottom outs.
I'm currently running 65 psi in the + chamber and 100 psi in the ++ chamber on the 170mm version, which is a little bit above what EXT recommends for my 160 lb weight. Conditions have been dry and fast lately – I could see dropping the main air chamber pressure for even more traction, but as it is there's been an impressive amount of grip.
It's the ease that the fork initiates its travel that really stands out. Even while climbing, the part of the ride where fork performance tends to take a backseat, the Era's ability to effortlessly smooth out chunkier sections of trail is noticeable. Tip the trail the other way and the Era truly shines – square-edged hits simply disappear, all without using up too much travel.
It's a unique sensation, and it took me a little bit to get accustomed to the feel of the Era. At first I thought I might need to run less than the recommended 15-20% sag, since it didn't seem possible to have such a supple beginning stroke without bottoming out off the smallest drop or sitting too deep in the travel. It turns out that wasn't the case at all - there was ample support for pushing into corners and dealing with compressions, all while reserving enough travel for the really big hits.
So far I've only had one harsh bottom out, which happened when a huck-to-flat turned to a huck-to-uphill; in other words, not an unexpected result. Since then, I've added 5 psi to the ++ chamber and haven't had any more end-stroke incidents.
How long will the EXT's sublime smoothness last? Will that crown design keep creaking at bay? I'll be continuing to put time in on the Era over the coming months – look for a follow-up report once I rack up enough miles. As it is, the Era is a remarkable debut from the Italian suspension specialists.
Studio photos: Alex Luise