From handmade wooden fixies in Adelaide to the tiny MR85 bearing at the heart of the RBC, Harbinger and Flying Lemon, Spinworthy has spent nearly a decade exploring what happens when old-school yo-yo ideas are treated as a starting point instead of a limitation.
Spinworthy Yoyos did not begin with a large product launch, a team of sponsored players or a carefully planned brand rollout. Its history is much more representative of the small-maker side of the yo-yo community.
It began with Glen Kempster making yo-yos, talking about them on the YoYoExpert forums, and becoming increasingly obsessed with fixed axle play.
In July 2017, Glen started the long-running “Show some wooden yoyos you’ve made” thread. At the time, he estimated that fixed axle accounted for about 90 percent of what he was throwing. A few weeks later he started another discussion simply asking, “Why fixed axle?” His answer gives a good explanation for nearly everything Spinworthy would become. Glen saw wooden fixed axle play as both a direct connection to yo-yo history and an area that still had enormous room for new tricks and ideas.
That combination of traditional construction and modern play would become Spinworthy’s defining characteristic.
From experiments to Spinworthy
By 2018, Glen was producing yo-yos under the Spinworthy name, with the Harbinger becoming the company’s first major release and eventually its flagship model. A contemporary history of the responsive revival places Spinworthy’s move into production and the release of the Harbinger in 2018.
The timing mattered.
Fixed axle had already been undergoing a creative revival through players and makers including Ed Haponik, Drew Tetz, TMBR and others. At the same time, modern responsive yo-yos such as the One Drop Deep State and Core Co. AlleyCat were demonstrating that responsive play did not have to be treated merely as the step before unresponsive 1A.
Spinworthy entered that environment from the wooden side.
The Harbinger was larger in diameter than many traditional fixed axles, with a narrow profile and a shape intended for stalls, regenerations and modern fixed axle string tricks. Glen continued revising it rather than treating the original design as finished. By September 2019, the public Spinworthy catalog was already listing the Harbinger V3.5.
That catalog also shows just how much experimentation was happening behind the scenes.
Alongside the Harbinger were the curvier Boon, the inexpensive Skinflint, the wide Ballsy, and the tiny Burley, which was turned from extremely dense Australian gidgee. Spinworthy was also making bearing yo-yos such as the POM Stout and organic Scone. The available woods ranged from maple and white oak to distinctly Australian species including jarrah, karri, spotted gum and sheoak.
Spinworthy was a wooden fixed axle company, but Glen was never particularly interested in staying inside that description.
Designing around the trick
One of the clearest examples came with the KNack, developed as a signature model for Kyle Nations.
Rather than simply changing the dimensions of an existing Spinworthy, Glen designed the KNack around Nations’ style of fixed axle play. Its concave faces were intended to make pull starts easier, while the gap and axle were tuned for fast response and strong regenerations.
Those concave faces were a small feature with a larger effect. Pull starts and face-start variations became easier to incorporate into fixed axle tricks without adding a mechanical hub or changing the basic simplicity of the yo-yo. Years later, when YoYoExpert forum members discussed the most influential yo-yos of the previous decade, the KNack was specifically cited for helping popularize pull-start dimples on fixed axles.
This is a recurring theme in Spinworthy’s designs. The goal usually has not been to maximize specifications. It has been to remove some particular frustration Glen encountered while actually playing.
That approach would become especially important in his work with MK1.
The Bloodcell becomes the RBC
The wooden Bloodcell was a Spinworthy fixed axle with a distinctive compact profile. When Mark Diehr of MK1 Yoyos collaborated with Glen on a metal version, they did not simply put a bearing into the middle and call it finished.
The problem was that a conventional bearing changed the geometry that made the wooden version work.
Their solution was the RBC, released in late 2021.
Instead of an A or C bearing, the RBC used an MR85, a tiny bearing with an outside diameter of only 8 millimeters. That dimension was significant because it matched the diameter of the axle in the wooden Bloodcell. Combined with a similarly narrow gap, the idea was to reproduce some of the behavior of a wooden fixed axle while adding the smoothness and spin time of aluminum.
The result was one of the most unusual modern responsive yo-yos of its period.
The RBC is generally credited within the community as the first yo-yo to use the MR85 bearing in this way. Two production runs sold out, and the design helped establish the tiny bearing as a legitimate tool for responsive yo-yo design rather than simply a piece of industrial hardware that happened to fit inside one.
That may be Spinworthy’s most visible contribution to yo-yo design, but it came directly from the wooden yo-yos that preceded it.
The new technology was being used to imitate something old.
The Survivalist
At roughly the same time, Glen was pushing fixed axle construction in another direction.
The Survivalist abandoned wood entirely.
After several experiments with different plastics, the production version was turned from recycled HDPE with a solid quarter-inch aluminum axle. The objective was a fixed axle that could live in a pocket, get wet, hit the ground and generally be treated with much less care than a handmade wooden yo-yo. Glen famously tested one by running it over with a car twice. It was damaged, but remained functional.
There is something very Spinworthy about the Survivalist.
It looks backward mechanically. There is no bearing and very little to go wrong. Yet its material and construction are thoroughly modern. It demonstrated that fixed axle did not have to mean wood, nostalgia or fragility.
A break, then a return
In October 2021, Glen announced that Spinworthy would be going on hiatus while he sold his house and packed up his workshop. A final Survivalist run and the upcoming RBC collaboration were already in motion, but regular production would stop while he relocated.
The pause ultimately became part of the Spinworthy story rather than its ending.
Wooden Spinworthys began appearing again, but the collaboration with MK1 also provided another way for Glen’s designs to reach a larger audience.
In 2024, MK1 and Spinworthy returned to the model that had started it all.
The aluminum Harbinger translated the proportions of the wooden flagship into a small-bearing responsive yo-yo. It again used an MR85 bearing, combining longer spins and aluminum construction with the narrow dimensions and regenerative play associated with the original.
A year later came the Plasm, a polycarbonate responsive developed by MK1 and Spinworthy as another descendant of the RBC concept.
Then Glen took the tiny-bearing idea somewhere less obvious.
The Flying Lemon
The Flying Lemon, released through YoYoExpert in 2025, is an unresponsive yo-yo.
It is also only 50 millimeters in diameter.
Glen had long been interested in undersized organic yo-yos, but felt that conventional bearings occupied too much space near the center of a small design. Even D and A bearings were not quite giving him the geometry he wanted.
So he returned to the MR85.
This time the bearing was widened to 4 millimeters, creating enough gap for unresponsive play while retaining the extremely small 8-millimeter outside diameter. The smaller hub allowed more freedom in the inner-wall geometry and weight distribution of a compact yo-yo. The resulting Flying Lemon weighed 57 grams despite its 50-millimeter diameter and was machined from 7075 aluminum.
The lineage is easy to trace.
A wooden axle inspired the RBC. The RBC proved the viability of the MR85. The same idea carried into the metal Harbinger and Plasm. Then the Flying Lemon used a wider version of that bearing to address an entirely different problem in unresponsive design.
Spinworthy had gone from trying to make modern fixed axle yo-yos perform better to using lessons learned from fixed axle construction to rethink the geometry of a modern unresponsive.
More than the yo-yos
Spinworthy’s contribution to the community is harder to measure than a bearing diameter.
For years, Glen has openly discussed materials, dimensions, response, axle construction, wood selection and turning techniques on the YoYoExpert forums. The wooden yo-yo thread he started in 2017 became a gathering place for other makers rather than simply a showcase for his own work.
That exchange has produced tangible results.
Eric Newlin of Wildwood Yoyos, for example, credits Glen Kempster and RC Yo-Yo’s Rob Cooley as major inspirations when he began turning his own yo-yos in 2022.
Glen has continued sharing that knowledge through his Wooden Yo-Yo Making Masterclass posts. Subjects have included shear scraping, wood selection and other parts of producing smooth, consistent wooden yo-yos. When someone on the forum asked in 2025 how to make a wooden fixed axle for a woodworking-class project, other members pointed directly to those Spinworthy guides.
That willingness to show the process matters in a hobby where many small manufacturers disappear without leaving much documentation behind.
Spinworthy has not just produced wooden yo-yos. It has helped preserve some of the knowledge required to make them.
Old technology, unfinished ideas
It would be easy to describe Spinworthy as part of the retro side of yo-yoing.
That misses the point.
A Spinworthy fixed axle certainly connects modern players with the earliest form of the yo-yo. It asks the player to manage response, spin and string tension in ways a modern unresponsive largely removes from consideration. But Glen’s work has rarely treated those restrictions as sacred.
Wood gave way to recycled HDPE. A fixed wooden axle inspired a miniature ball bearing. A responsive bearing system was eventually repurposed for an unresponsive organic. Player-specific needs produced new shapes and features. Manufacturing techniques were shared publicly so somebody else could take them further.
That is why Spinworthy occupies an unusual place in modern yo-yo history.
The company helped keep handmade wooden fixed axle yo-yos relevant during the modern responsive revival, but its larger contribution may be proving that fixed axle design is not a finished chapter. There are still problems to solve, tricks to design around, materials to experiment with and ideas from a century ago that can unexpectedly point toward something new.
For Spinworthy, the past has never been a destination.
It has been a workshop.