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Tested: EXT Arma HBC Shock

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Extreme Shock Arma HBC Review

Words: Max Neely
Photos: Tommy Wilkinson

The Arma HBC is EXT’s latest and highest spec downhill shock, offering external high and low speed compression damping adjustment, rebound adjustment and Hydraulic Bottom Out Control, hence the name HBC. EXT have one of the strongest suspension heritages in the business, with over half a century of experience under their belts. Franco Fratton is the main man behind EXT, a man who has worked with the likes of Ferrari and Lotus, not to mention Carlos Sainz on the World Rally Circuit. So for being relatively unknown in the mountain bike scene, they have more than enough expertise to create a World beater of a DH damper. Right now there’s no shortage of top performing shocks on the market and we were keen to review this bespoke Italian offering and see what sets it apart from the rest.

Out of the box you are greeted with a choice of 2 springs and an incredibly well finished product, certainly more industrial in appearance compared to the mainstream manufacturers but definitely no less impressive. For specs and initial impressions, click here.



I’d heard a few reports of EXT shocks, nearly all positive therefore expectations were high and the Arma HBC certainly did not disappoint.
We bolted it to a Solid Strike, a bike known to be fairly progressive in nature. The Vivid air shock it replaced often sat fairly deep in its travel and as a result, required a good bit of air pressure to even this out, which meant suppleness and grip was lacking.

The first thing you notice about the shock is the noise it makes when the shock is compressed, the tasty sound of oil being moved in and out of the piggy back. It’s not distracting when riding but you can definitely hear the beast working. The only other strange thing about the shock was the slight knock when you pushed down on the seat and let the shock fully extend back up. We contacted EXT to see if this was normal and they said the noise is from a titanium ball inside the cartridge that serves as an inertial valve, keeping track of the change from extension to compression, separating the two compartments. Once you got on the bike and were riding under sag, you couldn’t notice it.


Out of the box the settings were surprisingly good; creating a marked improvement in the handling of the bike straight away. The Arma inspired you to take bigger lines and not worry about heavy landings, it’s a shock that can take it and it does so in a very controlled way. There are some dampers on the market that deliver a velvety plush ride, almost to the point that you feel like you have a flat rear tire; this isn’t one of them, you get awesome feedback through the tires about your grip point and where you are on the trail. This allows you to plough through stuff if you want, the control is there, but still allows you to maneuovre and hop the bike as you have a real perception of what is underneath you.

Let’s just say its a damper that allows you to push your limits that bit more and gives you the confidence to let the brakes off when it gets a wee bit spicy.

In a lot of ways, this is a case of setup – how many people are running a shock that has the capability to work well but it’s set up to work like a donkey? That’s where I think the real value of the EXT is, the custom tuning means the shock is going to be right for your weight and frame design straight out of the box; a major leap towards getting your setup dialed.

Adjustments are via an allen key / 13mm spanner for low/ high compression and HBC and a standard twist dial for rebound. The increments seem to make a difference and 1 or 2 clicks either way is noticeable. We reduced the low speed compression and dialed in the rebound to provide a bit more pop and the the shock felt great. Rebound was nice and predictable for jumps, providing pop off the lips while still keeping control over repeated hits and compressions. The shock seems to keep you moving forward really well, not using unnecessary amounts of travel; it just doesn’t seem to hang up between impacts and encourages the bike to skip over hits in quick succession. This low “hysteresis” that they talk about really is an important feature of the Arma; it feels finely tuned with a really quick response time giving new levels of grip and feedback.

So who is this for? It’s for the rider who is looking to upgrade for more performance out of their frameset. Perhaps someone who likes something different and values the ability to have the shock tuned for your weight and specific suspensions design. The light weight ( we think it’s the lightest DH coil shock on the market at 690grams) would make for a light build without having to go for an airshock. At 750 Euros , it isn’t cheap but with 2 springs and custom tuning, we think it’s a pretty good deal. Remember , EXT are by no means new kids on the block when it comes to suspension , with an F1 and motocross pedigree they know what works as well as anyone out there. Over the course of the 6 week test, the Arma was battered down wet Welsh hillsides, rough braking bump filled bike parks and root infested natural trails and it never seemed fazed.

Spec and Pricing


Price – €750

Weight – 690gr with coil for 241/76 mm

Available sizes- Personalized lengths on request
222 / 70 mm
241 / 76 mm
267 / 89 mm


We wanted to know a bit more of the background of the shock and why EXT had chosen to do things a certain way, so we asked the engineers a few questions.

1. DW:  What are the key differences between the technology in the Arma HBC in comparison to other shocks on the market?

EXT: Our shocks are built with high performance materials like titanium and ergal. So we can build very light shock but also very strong. Furthermore our valve have a high flow of oil and a very low pressure on the external tank. Other manufacturers normally use a high pressure inside piggyback tank. We use a different technology that we call HBC (Hydraulic Bottom-Out Control). Inside the shock we have two different pistons. One of this controls the last millimeters of travel and the HBC. So the behaviour of the shock change only on the last millimeters for have a good control of bottom out, but on the main travel you can have a very “plush” feeling.

2. DW: You custom tune each shock to the riders weight, bike design , pedal choice and even wheel size is taken into account. Why is this tuning process important and what performance advantages does this give the EXT over running a stock “off the shelf” shock?

EXT: We think that every suspension scheme have a different behaviour, like every rider have a different style. We do custom shock because we think that only few setting (like the other manufacturers) are not enough. There are a lot of variables on a suspension, geometry, wheels size, etc. So is better to test it before and do a custom setting for every shock. Every shock is customized for the rider and the bike.

3. DW:  What is the recommended service interval for the shock?

EXT: Service depend of your use. If you do races we suggest a complete service after 6 months of riding (60 hours riding). If you do a normal use we recommend a service after 12 months (100 hours riding).

4. DW: Why do you include two springs with the shock?

EXT: We include two spring to allow riders more customization. You can ride different trails and you may have different feeling with two spring. Or in enduro, for example, you can ride with or without a backpack.


So, overall, we think it’s a winner. Yes it’s noisy but like a finely tuned machine, it’s for a reason. The performance and support offered is superb and if you in the market for a shock upgrade, EXT should certainly be on your list. We’re hoping to get our hands on their “Storia” Coil shock to see if it can have a similar revamping effect to lacklustre suspension on an Enduro rig.

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