DVO Topaz Air Shock

When it comes to improving a bike's performance, one of the key areas to consider is suspension. Combined with your tires, it is by and large responsible for controlling your bike's interaction with the trail beneath you. DVO, short for Developed Suspension, has a long history in our sport and knows a thing or two about how to perfect that interaction, maximizing traction and control on your mountain bike. Whether your goal is outright comfort, speed, or a combination of the two, their suspension products offer the tuning means to make it happen. We've been torture-testing the DVO Topaz T3 Air shock for well over a year and dialing in our ride. It offers some unique design features compared to the majority of rear shocks on the market.

Highlights

• Intended Use: Trail, all-mountain and enduro riding
• Spring: Air; volume reducers can be used in both the positive and negative spring
• Damper unit: Compression loader system with bladder
• Compression: Three position dynamic adjustment via easy access lever (internally tunable if needed)
• Rebound: Nine clicks of dynamic adjustment via piston and shims (internally tunable if needed)
• Rubber bladder pressure can be adjusted from 170-200psi
• Bushing: 15mm IGUS bushings with 6mm, 8mm or 10mm mounting hardware options
• Cooling fins on piggyback reservoir for improved heat management
• Five standard eye-to-eye/stroke options
• Six metric eye-to-eye/stroke options and six trunnion options
• Specialized Enduro and Stumpjumper-compatible options
• Weight: 390 grams (verified, 200x57mm size)
• Carrying case, shock pump, and volume reducers included
• MSRP: $500 USD

Bladder Versus IFP in the Topaz

While there are several small details that all add up, the main feature that sets this shock apart is the use of an easily-adjustable bladder instead of an internal floating piston (IFP) inside the finned reservoir. This is a trickle-down from DVO's Jade Coil downhill shock.

A bladder is basically a ballon made from a stretchable material that can expand or compress. On the Topaz, it is filled with air and seated to the reservoir end cap.

An IFP is more common in mountain bike suspension, and is a moving piston with at least one o-ring seal that slides up and down inside the reservoir.

Both a bladder and IFP separate air (or nitrogen) from damper oil within the shock and are used to pressurize the system. As a shock is compressed, oil is displaced within the system and starts to compress the bladder or IFP. When the shock goes to extend again, the bladder pushes the oil back in the opposite direction. Pressurizing the bladder or IFP helps keeps the rebound chamber from cavitating during quick compressions.

As DVO describes it, "Cavitation occurs when vapor bubbles form in the suspension fluid due to a decrease in pressure."This video clip is an example of cavitation in a shock. When cavitated, the subsequent rebound stroke produces zero damping while the cavitation bubble collapses. In short, you don't want it to happen.

Increasing bladder or IFP pressure increases the shaft speed at which cavitation will occur. DVO capitalizes on this fact by making their bladder easily adjustable from 170-200psi with a shock pump, and makes the general statement that lighter riders can run less pressure and heavier riders should run more.

Adding pressure to the bladder does not create damping – instead, it acts directly on the shock damper rod area and adds to the overall spring force during both compression and rebound. In an IFP system, tuning via IFP pressure creates added breakaway forces (the force needed to get the shock moving), so it is typically set to a predetermined pressure and left alone essentially hidden inside the shock. Overcoming breakaway force has lead to larger negative springs and systems like RockShox's Counter Measure. Bladders have reduced breakaway force compared to IFPs due to a lack of seal friction, however.

Thanks to a user-serviceable design without the need for specialty tools, service can be performed in the comfort of your garage.

There has, however, been some recent and concerning wear occurring on the damper body that will eventually lead to worn seals. Removing the air can to inspect the inside of the shock revealed wear on the metal lip just above the dust seal, near the white bushing. No dirt or other contamination was found. DVO says this can occur when there is a frame alignment, bearing, or hardware issue, and will generally only occur on one side of the shock as it did on ours. They've only seen the issue a handful of times. An initial inspection of our frame bearings revealed no glaring issues, and the linkage moves freely with no play. Given the sudden nature of the wear, it's likely that something is amiss.

DVO backs the shock with a two-year warranty.

Things That Could Be Improved

More defined detents on the rebound adjuster would be great, and the compression lever often feels a bit too easy to turn. The compression lever's size may also prohibit the firmest setting from being used on bikes with a water bottle.

DVO provides a wealth of knowledge via their tech website, including setup, tuning, and service procedures. A larger, more complete database of DVO or frame manufacturer confirmed base tunes would be helpful for many. There is currently an archive of user-submitted tunes, but these can be hit or miss. Having something backed by DVO or frame companies could ensure a better starting point for most users.

As previously noted, we feel the shock could also use a bit more high-speed rebound damping for use on the Smuggler. DVO does make the tools/knowledge/resources available to make almost any change happen, however, and support is just a quick phone call away if you have a question or need advice. When we reached out about how to tackle this on their digressive damping design, DVO said they "suggest lifting the stack to eliminate the dish on the rebound side of the mid-valve, which will make the damping a little more consistent through the entire range." This is something we'll try in the future.

What's The Bottom Line?

The DVO Topaz air shock made a substantial improvement to the suspension performance on our Transition Smuggler test bike, and with enough tuning time the quickly-adjustable bladder system has allowed us to find a setting that brings the bike to life while maintaining excellent traction and control. Those seeking to tune out some of the chaos of bumpy trails will be very pleased with its relatively low breakaway force and ultra-supple feel – this alone makes it a worthwhile upgrade. Quality internal components, a user-focused design, and excellent customer support make it serviceable at home, which will save you both time and money in the long run.

Visit www.dvosuspension.com for more details.

About The Reviewer

Brandon Turman - Age: 31 // Years Riding: 16 // Height: 5'10" (1.78m) // Weight: 175-pounds (79.4kg)

"I like to have fun, pop off the bonus lines on the sides of the trail, get aggressive when I feel in tune with a bike, and really mash on the pedals and open it up when pointed downhill." Formerly a Mechanical Engineer and Pro downhill racer, Brandon brings a unique perspective to the testing game as Vital MTB's resident product guy. He has on-trail familiarity with nearly every new innovation in our sport from the past several years and a really good feel for what's what.

Photos by Courtney Steen and Brandon Turman