EXT Arma V3 Rear Shock 9.5 x 3.0: Setup and Fitment for Downhill E-Bikes

A downhill e-bike hits the rear shock harder than almost any other part. The EXT Arma V3 rear shock in the 9.5 x 3.0 inch (241x74mm) size is a four-way adjustable coil shock built with downhill in mind, and HPC offers it as a custom-built, custom-tuned upgrade. This guide covers what the Arma V3 is, what the 241x74 size means, which bikes the listing points to, how to approach spring rate and sag on a heavy bike, and how it compares with the DVO Jade.

EXT Arma V3 9.5 x 3.0 at a glance

What the Arma V3 is

EXT engineered the Arma V3 with downhill in mind. The product page highlights several details that matter on a heavy e-bike:

• A 14 mm shaft, which the listing says is 50% larger than most other coils on the market, to help deal with large side-loading events.
• Four-way adjustment: low-speed compression (LSC), high-speed compression (HSC), low-speed rebound (LSR) and user-adjustable hydraulic bottom-out control (HBC).
• A rebound circuit that separates bump and rebound oil flow, with an ultra low-friction coating.
• Very low reservoir pressure (75 PSI) for maximum sensitivity, and a low-friction seal.
• Wider-range HBC, so riders can run softer spring rates and still have good support at the end of the stroke.

The listing also notes the redesign is more frame friendly, with metric and imperial sizing and both classic eye-to-eye and trunnion mounts.

What 9.5 x 3.0 (241x74) means

The two numbers describe the shock's size. 9.5 inches (241mm) is the eye-to-eye length, measured between the centers of the two mounting holes. 3.0 inches (74mm) is the stroke, the distance the shaft travels. Your frame is built around one specific eye-to-eye and stroke, so the shock you choose has to match. Do not substitute a different size without checking, because it changes the ride height and geometry.

Which bikes it fits

The product listing is tagged for the Revolution and Revolution X. HPC's Revolution family is a hand-welded, USA-built downhill and freeride platform, covered in our Revolution lineup guide. EXT also notes that every shock should be test-fit to the frame and cycled through its travel to confirm frame compatibility and clearance, especially when aftermarket parts change the stock geometry or linkage. If you are not sure the 241x74 size matches your bike, send us your model and year and we will confirm before you order.

Spring rate for a heavy, high-power bike

Spring rate is the foundation of your setup. Everything else, including the damping, depends on it.

• Use your total weight. Rider, gear and the bike itself all load the spring, and a high-power e-bike weighs much more than a pedal bike.
• The listing offers spring rates from 325 to 600 in 25-lb steps. Orders needing a heavy-duty spring (650 lb and up) come with one spring only, and an additional HD spring can be bought for $50.
• Leave it to us if you are unsure. Every Arma is custom built and tuned for the specific bike, rider weight and riding style. If you are not sure about an option, leave it blank and HPC will get in touch with any questions.

Setting sag

Sag is how far the shock compresses under your weight. To measure it, put the bike on level ground, in your riding kit and riding position, and compare the shock's compressed length to its fully extended length. Then adjust spring preload until you reach the sag figure recommended for your bike. Too little sag and the wheel cannot follow the ground; too much and you will sit deep in the travel with nothing left for big hits. A heavy bike at speed needs a spring that holds its position, so if you cannot reach your target sag with the spring rate on hand, change the spring rather than winding on more preload.

The same order applies as for forks, and our EXT Vaia setup walkthrough covers it in detail: spring first, then sag, then rebound, then compression, changing one setting at a time and riding the same section between changes.

Using the four adjusters

1. Rebound (LSR): start slow and speed it up until the shock returns quickly without bucking you.
2. Low-speed compression (LSC): controls support under pedaling, braking and cornering.
3. High-speed compression (HSC): controls how the shock handles sharp, square-edge hits.
4. Hydraulic bottom-out control (HBC): adds support near the end of the stroke. It lets you run a softer spring without bottoming harshly.

If the rear dives or wallows, the answer is usually a firmer spring, not more compression damping.

Arma V3 vs DVO Jade

Both are coil shocks, and both suit heavy, high-power downhill bikes, where a coil's consistent feel on long, rough descents is the point. Our DVO suspension guide describes the DVO Jade Coil ($600) as DVO's premium coil shock.

• Arma V3 ($749): four-way adjustable with user-adjustable HBC, a 14mm shaft, and a hydraulic setup that is custom built for your bike and rider.
• DVO Jade ($600): a premium coil with a consistent, linear feel. Rear shocks come in many sizes, so we confirm the right Jade for your frame.

Choose by what you value. If you want the most adjustability and a shock built and tuned to your weight and riding, look at the Arma. If you are fitting DVO suspension across the bike, the Jade is the match. For the bigger picture, see High-End E-Bike Suspension: Downhill Forks and Coil Shocks.

Availability and ordering

Because each Arma is custom built and tuned, the product page shows no stock on the shelf. Tell us your bike, weight and riding style when you order, and contact us for current availability and lead times.

Ride responsibly

Downhill e-bikes are for private land, bike parks that allow them and closed courses. Check local rules, wear full protective gear and service your suspension regularly.

Shop the EXT Arma V3, or see more HPC suspension.