While they’ve only been in mountain biking since 2014, Extreme Racing Shox have been around since the 1980’s with a history of working in motorsport, collaborating with companies such as Honda and Hyundai. Unusually, their mountain bike shocks are designed to work at low pressures – think 40PSI instead of 150. You won’t be tinkering with a shock pump though – they’re coil shocks that work with a sealed gas piston plus oil valves to control bottom out.
We went to see them at Eurobike and get the skinny. They’re offering two shocks, the Arma HBC for downhill, and the Storia LOK, aimed at enduro.
The is the Arma HBC; it’s a coil downhill shock that has no lockout, but does have progressivity control via their HBC, which stands for “Hydraulic Bottom out Control”. It’s the black allen fitting at the top of the shock, has eight clicks, and means that you can run a softer spring for more traction without blasting through the last bits of your travel all the time. These concentric dials below the HBC are the high (HSC) and low speed compression (LSC) controls. The LSC is in the centre, adjusted with a 4mm allen key, and has 12 clicks. The HSC is outside that, adjusted with a 12mm spanner, and has 14 clicks. Every shock EXT sell is tuned for the bike and rider it’s going to work with: from frame design, to weight, to riding style and whether or not you prefer clips or flats, they take all of this into account before setting the shock up and sending it out. They had this large HBC demo model on the stand, and to be honest, with a thunderstorm hammering on the roof of the exhibition hall and a slight language barrier, it wasn’t the easiest thing to follow. Basically though: EXT’s valve and gas piston designs mean more than 50% of the hydraulic resistance can be dedicated to controlling bottom out in the last 15% of the stroke, and the way they’ve designed their shocks completely separates rebound and compression adjustments. While the large mockup has an air valve on it, certain things on the shock are only adjustable by dealers. As a user, as well as the setting dials, you can tune it with different springs and preload; EXT supply two springs with each shock. The black dial you can just see near the tip of this display model is the rebound adjuster, located here on both the Arma HBC and the Storia LOK. Here’s a cutaway of the Storia LOK enduro coil shock. Unlike the Arma, in place of the HBC control it has a 2 position hydraulic lockout assembly instead. That lockout also has a blow-off valve just in case you leave it locked and hit something big. The exact behaviour of the lockout position is customisable at the factory or any EXT dealer – it might be that you want a super firm lockout for blasting up fire roads, or perhaps you’ll want a slightly more supple one to balance power and traction on more technical climbs. Most of the parts are either 7075 T6 aluminium, or titanium. The 200×57 version of the Storia LOK weighs 620 grams including the spring. Pretty much nothing is off the shelf from EXT; with their heritage in motorsport they’ve been able to engineer their own proprietary coatings, and springs made from a special steel formulation developed with Honda Racing. Springs come in four lengths (105, 117, 140, and 175mm), each available in four weights (275, 300, 350, 375lbs). EXT do sell their springs separately, and along with various spacers they can work with many other shocks from other brands. Pricing is not cheap at €799+VAT for either the Arma or the Storia, and they don’t sell them straight off the shelf. To buy one, you have to email EXT and have a conversation, as each shock is customised to suit the rider and bike. As well as shocks and springs, EXT have their own range of oils and lubes. Along with their shock designs, they’ve engineered their lubricants to stay stable and consistent over wide temperature ranges. This “High Performance Gel” seemed like a bit of an oddity – they said it’s oil soluble, used for reassembling suspension, and helps eliminate stiction.
If you’re curious and want to find out more, you can read more on the
Extreme Racing Shox website.