If you were a bike nerd in the 90s, you probably remember Spinergy’s iconic Rev-X wheels. With their eight carbon spokes, the futuristic-looking hoops were all the rage in the pro peloton and domestic race scene. And while the Rev-X is no more, Spinergy’s current offerings are anything but low tech. Utilizing the company’s patented PBO composite spokes, Spinergy wheels are available for practically every discipline, including four gravel models. So when the California-based company asked if I’d like to test their new 650B GX gravel wheelset ($599 MSRP), I simply couldn’t say no.
Spinergy’s gravel wheelsets may differ in rim profile and material, but all four GX models share the same hubs and spokes. Rolling on stainless steel Enduro sealed bearings, the Spinergy GX gravel hubs can be configured with either thru-axles or quick releases. The Spinergy-designed, Hadley alloy freehubs are offered in Campy, Shimano, or SRAM (XD, XDR) versions, and the three, double-wide pawls engage 24-tooth drive rings. The quick release hubs that I tested were easily disassembled with 17- (rear) or 18-mm (front) wrenches, requiring no maintenance or adjustments after three months of heavy use.
With their 20 mm height, the GX gravel wheelset’s alloy rims may seem a bit conservative compared to the deeper (32 mm) rims found on Spinergy’s GXC and GX32 hoops. But what the 20 mm rims lack in depth, they more than make up for in width. Measuring 28 mm wide with an inside width of 24 mm, the GX’s tubeless-compatible rims are ideal for 36-42 mm tires, and can accommodate tires up to 54 mm wide. The rims’ sandblasted, black anodized finish proved extremely durable, and Spinergy offers rim decals in a range of color choices (which conveniently match the PBO spokes’ colors).
Remember when I said that all Spinergy GX gravel wheels utilize the same spokes? Well, they’re not just any spokes. Instead of steel (or even aluminum), Spinergy’s PBO spokes are constructed from polyphenylene bensobisoxazole fiber. Each spoke contains over 30,000 strands of the aforementioned fiber, and is encased in a chemical resistant, water- and UV-proof composite wrapper. What’s the advantage of composite over conventional spokes? According to Spinergy, their PBO spokes are three times stronger than steel spokes, but weigh half as much as their metallic counterparts. The company also claims that the flexible spokes absorb impacts better, as well as reducing vibration transmitted to the rider (thereby improving comfort and reducing fatigue).
So how much weight do those composite spokes save? Good question. My sample 650B GX wheelset (Q/R axles, XD driver) came in at 1441 grams (668 grams front, 773 grams rear). Those weights include the stock tubeless rim tape and 44 mm Muc-Off alloy valve stems that I installed. By comparison, Shimano’s GRX WH-570 wheelset comes in at 1657 grams, a pair of Stans Grail MK3s tip the scales at 1675 grams, and the PUB 734 Gravel wheelset weighs 1565 grams. The GXs’ light weight was most noticeable when climbing–especially on the short, punchy climbs that are common in and around Boulder, Colorado. And when paired with lightweight tires such as the 450-gram Rene Herse 650B x 48 Switchback Hill, I found myself pedaling out-of-the-saddle on hills where I would normally stay seated.
Speaking of tires… I’ve found that some companies’ claims of tubeless compatibility can be rather optimistic. I’m happy to report, however, that I didn’t experience any difficulties installing or seating tires on the GX wheelset’s rims. In addition to the aforementioned Rene Herse tires, I also tested the Spinergys with 42-50 mm tubeless-compatible tires from IRC, Schwalbe, Specialized, Teravail, Vee Rubber, and Vittoria. Most of my time was spent on 47-48 mm tires, and I found the GXs rims’ 24 mm internal width improved tire stability during cornering, especially when running very low pressure (20-25 psi front, 25-30 psi rear).
As with much of my product testing, I pulled the GX wheelset into service for both recreational use and commuting. With the latter, that often meant careening over local trails on my rack-and-pannier-equipped Breezer in the pre-dawn and evening hours. Between the wheels’ low spoke count (24 front and rear) and composite spokes, I had reservations that the Spinergy GX gravel wheelset would be up to the task. My concerns turned out to be unwarranted, however, as the wheels have remained perfectly true and didn’t exhibit any unwanted flex or rotor rub (which has not always been my experience with lightweight, quick-release disc wheels/hubs).
Are the Spinergys more comfortable than conventional, wire-spoke wheels? That’s a tough question to answer. While I definitely noticed–and appreciated–the GX Gravel wheelset’s light weight, I’m unsure whether the composite-spoked hoops reduced vibration or rider fatigue. My hunch is that the spokes’ benefits are cumulative, and the difference in comfort is more apparent on longer rides with extensive high-frequency vibrations (which would be similar to the benefits espoused by carbon frame/fork manufacturers). While the GXs might not be my first choice for bashing through rock gardens, they proved reliable for everyday use, and I would not hesitate to use them for events such as Colorado’s SBT GRVL or the Gravel Worlds in Nebraska.
Disclosure: Spinergy provided review samples for this article, but offered no other form of compensation in exchange for editorial coverage.