Review: Spinergy’s GX Gravel and Z Lite Disc PBO-Spoke Tubeless Wheelsets

Many cyclists obsess over the ride quality of their bikes and look for slight contours or shapes in frames to add a bit of compliance during bumpy riding. Some take it a bit further, seeking flexy seatposts, suspension stems and cushy bar tape.

All of these tweaks have merit and can make a difference. Yet too often we forget the very first items to come into contact with the bumps: tires and wheels.

While we won’t debate tire volume, pressure and construction here, wheels’ role in ride quality is often overlooked. They translate anything that your tires don’t absorb into the frame and fork.

Spinergy hopes those vibrations and impacts will be less for those who are riding its wheels.

Spinergy Returns to Drop Bar Dirt Riding

Old-timers may remember how Spinergy dominated the top-end of cyclocross racing in the 1990s. The eight-spoke carbon fiber wheels were the choice of World Champs Daniele Pontoni and U.S. National Champion Jan Wiejak, as well as amateurs hoping for a winning look or ride.

Wiejak stormed to a National Championship in Leicester, Mass, riding Spinergy Rev-X wheels. © A. Yee

While engineers and wannabe engineers can endlessly debate the merits of using carbon fiber spokes in both tension and compression, Spinergy wasn’t the last of companies to do so. Lightweight and the now-defunct Madfiber both did the same, albeit with more spokes.

Today, Spinergy is still focused on making composite-spoked wheels, but now it employs Polyphenylene Bensobisoxazole (PBO) fiber spokes in a more traditional-looking build. The goal is both comfort and weight savings, not aerodynamics.

Some might remember Spinergy had offered composite Spox spokes made from Vectran in the past, which touted the same benefits, but were prone to stretching and then breaking.

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The Spox are long gone, and the company says its PBO spokes have many years and miles of testing and a proven track record. They don’t stretch and don’t lose tension over time, and are said to be much stronger than the old Spox. Spinergy has been using the PBO spokes for over ten years with much success.

Spinergy's PBO spokes come in 8 different colors, including a more stealth black. © Cyclocross Magazine

Spinergy claims the PBO fiber spokes are three times stronger than steel at half the weight. There is a water and UV resistant composite coating that protects the fibers and is available in 8 colors. Another claim is the PBO spokes have impact absorbing and vibration damping qualities that give a more comfortable ride. A lightweight, comfortable ride sounds pretty appealing for cyclocross and gravel. Do such claims ring true?

We received two models for testing late last year. An early model of the new GX gravel wheels, and the Z Lite Disc for review.

The Builds

The $799 Z Lite Disc features an aluminum rim that measures 18mm internal, 23mm external and is 24mm deep. This is the same rim as the rim brake Z Lite, with a visible brake track. It employs 24 two-cross spokes both front and rear on the drive side, with radial on the non-drive side.

Our test set tipped the scales at 1,591 grams for the set, quite a bit more than the 1,487-gram list weight. Spinergy reports that its newer rim extrusion and flat black anodization bring the weight back down to around 1,500g.

Our review package had bright green PBO spokes, making them hard to miss, but if you're looking for something that matches your bike, there are eight other options (black, blue, green, orange, pink, red, white, yellow and purple).

Spinergy's PBO spoke Z Lite Disc wheelset is available in shocking spoke colors, but offers a smooth ride. © Cyclocross Magazine

The $849 GX gravel wheels serve up specs that many of our readers will be more excited about. Spinergy swaps in a much wider rim for the GX gravel wheels, with a 24mm internal, 28mm external, 20mm deep matte “sandblast” black alloy rim. The GX wheels also use 24 PBO spokes front and rear. There's also a 650b version available, which is, as you might expect, a tad lighter at 1450g, and retails for the same price. Prefer a deeper rim? Spinergy offers a carbon rim GXC version that offers a 32mm deep rim, but no weight savings.

Spinergy's PBO spoke GX gravel wheelset weighs under 1500g and retails for $849. © Cyclocross Magazine

Our GX wheels were quite stealth—black spokes on a black rim—and didn’t beg for attention. Unless you got close and saw the bigger spokes, you might not notice they’re any different than standard wheels. With eight colors of PBO spokes available, you can choose whether your wheelset begs for attention or rides by quietly. You can even mix and match colors of spokes with a custom build

The GX wheels have a list weight of 1,520g, but unlike our Z Lite Disc wheels, our set was lighter that list weight, at 1,505g. Since their release, Spinergy has opted for lighter end caps and axles, and lists the weight has dropped to 1,495g. Of course, the weights will vary a bit whether you choose QR or thru axle.

Spinergy's PBO spoke GX gravel wheelset offers different end caps for QR or thru axles. © Cyclocross Magazine

Both wheelsets use Spinergy’s proprietary nipples, the truing process, if necessary, is a bit more involved than with standard wheels. You hold the external nipple (really a spoke end) to keep it from rotating with Spinergy’s wrench (supplied), while tensioning the nut from inside the rim with a T-handle socket wrench.

Spinergy's PBO spokes are trued by tensioning the nut with a T-wrench, while holding the spoke end with a separate tool. © Cyclocross Magazine

That requires you to remove the tire and tubeless tape, but truing (or replacing a spoke) should hopefully be a rare if not nonexistent situation, given the spoke’s touted strength.

Spinergy's PBO spoke Z Lite Disc wheelset uses the same rim brake rim as the Z Lite, opening up opportunities for use on both rim and disc brake bikes. The spoke end uses a special tool to hold it in place to prevent twisting during truing. © Cyclocross Magazine

Tubeless tires popped on easily, without issue, with a compressor pump. With sealant, they passed our finger burp tests, and more importantly, didn’t burp out on the trail or gravel road.

Spinergy's PBO spoke GX gravel wheelset features a 20mm deep, 24mm (internal) wide rim with subtle bead-retaining lip. © Cyclocross Magazine

The Ride

“You will feel the difference once you ride,” said Spinergy’s Rene Leva, Director of Sales.

We were anxious to see if those words would ride (and remain) true.

We initially split up the two wheelsets between two testers and set off to ride our typical haunts. The GX wheel, with the familiar, versatile 38mm Ritchey Megabite tubeless tires, surprised with a quiet, smooth ride. The best description was that it felt like we had a few psi less in our tires, but without any additional squirm.

Spinergy's straight-pull PBO spoke GX gravel wheelset. © Cyclocross Magazine

To put it in context, just riding along on both pavement and dirt roads, it was more noticeable than typical differences in frame material or construction, but less than adding suspension components like stems or posts, or swapping a burly nylon 30tpi tire for a high-quality supple one.

You might be able to feel a difference, but will it make a difference? Add up that vibration absorption over the course of an all-day gravel event and it might.

The Z Lite Disc wheelset didn’t quite leave the same impression as the GX wheels, but our tester followed Spinergy’s recommendation of using cyclocross-width tires and rolled on burly 415g ERE Research Tenaci 33mm tubeless tires. The combination of the narrower tire, narrower rim and heavier wheelset masked much of the potential benefits that the PBO fiber spokes promise.

Spinergy's PBO spoke won't win any wind tunnel tests, but the company has a bladed version for an upcharge. © Cyclocross Magazine

Because tire choice and tire volume play a major role in ride quality, we’ll say this. For cyclocross and gravel tires, the GX wheelset is a better riding wheelset, simply because of the added tire volume the 6mm-wider rim provides. The wider rim serves up about 2mm more tire width, depending on tire size, with better support in cornering.

The Z Lite Disc is interesting due to its rim brake and disc brake possibilities for more than one bike in the quiver, but that’s most likely only useful as a rim brake wheel on the front, unless you have an old rim brake mountain bike 29er around.

Spinergy's PBO spoke come in nine different colors. You could even choose several colors for a custom build. © Cyclocross Magazine

Vibration absorption is nice and all, but does that translate into a whippy, flimsy wheelset? The spokes have more flex when you squeeze a pair in your hand, yet the lateral deflection of the wheel when leaning on the rim is no more or less than a typical wheel with metal spokes. In sprints and on steep climbs, our amateur thrashing and overly-ambitious bike swinging didn’t translate into any unwanted squirm that we could attribute to the wheelsets.

Spinergy's PBO spoke GX gravel wheelset has 2x lacing on the drive side, and radial on the non-drive side. © Cyclocross Magazine

Will the proprietary PBO spokes translate into measurable benefits? That’s beyond the scope and lab equipment of this review, but perhaps the question is, will you appreciate a smoother ride? And could you feel fresher after many hours of riding a smoother wheel? Our gut says it’s possible, if not likely.

Spinergy's PBO spoke Z Lite Disc wheelset uses PBO fiber spokes that are said to be lighter, stronger and more impact resistant than steel spokes. © Cyclocross Magazine

Could the larger diameter spokes (compared to steel) and increased aerodynamic drag could offset any gains from a smoother ride? Intuition says yes, but Spinergy also offers its PBO bladed spokes as an option. So if you’re out to set speed records, you might want to opt for that $100 upcharge.

The Verdict

Many pay thousands for compliance promises of carbon rims, new frame shapes and premium butted frame tubes, while ignoring the very items that are the first to hit the bumps on the road and trail. Wheels are one of these items.

Opting for PBO spokes for ride comfort doesn’t make sense if you’re riding stiff tires at too-high pressures. We’d even go so far to say if you’ve wrapped your bar with Benotto ribbon or shellacked cloth tape, there are far more cost-effective upgrades than new wheels to increase rider comfort, aesthetics or period correctness be dammed. But if you’ve got your tire game dialed, the Spinergy GX wheels might make a bigger difference than many more pricey upgrades in smoothing out your ride.

Spinergy's PBO spoke GX gravel wheelset comes with a Shimano/SRAM 11-speed freehub, but an XD driver is available. © Cyclocross Magazine

The Spinergy GX gravel wheels, while we had them, became our wheelset of choice for two months. They handled muddy cyclocross, bumpy gravel and everything in between and remained straight and true while offering a smooth ride.

Spinergy has quietly come a long way since its Rev-X and Spox Vectran spokes. $849 for a sub-1,500g wheelset is more than competitive with heavier carbon hoops that retail for well over $1k. We’ll admit we were skeptical at first, but the GX wheels have won us over. The exotic PBO spokes offer a nice ride at less-than-exotic prices, making the GX worth a look if you're in the market for new hoops.

Spinergy Z Lite Disc Specs:

MSRP: $799 with PBO spokes, $899 with PBO bladed spokes
Lacing: 24 two-cross front, 24 two-cross drive side, radial non-drive side
Weight: 736 grams front, 856 grams rear, 1591 grams pair (1487g list, newer wheels have lighter extrusion and anodization)
Rim: aluminum tubeless with hook beads, 23mm external width, 18mm internal, 24mm deep with brake track
Axle: QR and thru, with swappable end caps

Spinergy GX Gravel Specs:

MSRP: $849 with PBO spokes, $949 with PBO bladed spokes
Lacing: 24 two-cross front, 24 two-cross drive side, radial non-drive side
Weight: 1505 grams pre-production (709 front, 786g rear, 1495g set list weights for 700c, 1450g set list for 650b)
Rim: aluminum tubeless with hook beads, 28mm external width, 24mm internal, 20mm deep, disc only
Axle: QR and thru, with swappable end caps

More info: spinergy.com

Andrew Yee and Clifford Lee contributed to this review.

Spinergy GX Gravel and Z Lite Disc Wheelset Photo Gallery: