Origins: How the AheadSet threadless headset changed bikes forever

Almost without fail, modern road bicycle headsets have identical configurations. From top to bottom, there’s a headset preload cap and bolt, a stem that clamps to the outside of the steerer tube, an upper headset cover and bearing seat (or race), a bearing, a head tube, another bearing, and another bearing seat. Several slight variations on this theme exist, but by and large, the basic theme carries over to nearly every high-performance bicycle made today. It wasn’t always this way. CyclingTips U.S. technical editor James Huang takes a look back at when forks were threaded and headsets came loose — and how an ambitious young mountain-bike racer with a knack for invention changed everything.

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The standard headset setup was very different in the late 1980s. Whereas modern forks have steerer tubes that are smooth from top to bottom, forks from yesteryear were several centimeters shorter and their uppermost sections were externally threaded. Up top were two nuts: one that was usually flanged and directly integrated the upper bearing race or seat, and another nut that sat above it. Rotating the lower nut down against the upper headset cup preloaded the bearing assembly, and tightening the two nuts against each other locked in the adjustment.

Meanwhile, the corresponding “quill” stems had extensions that inserted down into the steerer tube. A long bolt ran the full length of that extension and attached to a small wedge mechanism at the bottom. Tightening the bolt expanded the wedge and secured the stem against inside the steerer tube.

From an engineering standpoint, it was far from an elegant solution. Precise bearing adjustments were tricky, those two nuts were prone to loosening on rough terrain, and two large, specific wrenches were required to service the system — wrenches that no one ever carried on a ride.

And whereas carbon fiber was just starting to become accepted as a viable material for bike frames, the need for threads on steerer tubes meant they had to be made of metal.

Nevertheless, most people at the time thought the system worked just fine — though in hindsight, that was perhaps more due to the fact that no viable alternative existed.

Either way, John Rader wasn’t like most people.

An enthusiastic mountain-bike racer who came up in the early days of the sport, Rader was the son of a former race car driver. His father, Homer John Rader Jr., spent a lot of time behind the wheel, but was also intimately involved with the design and mechanics of the vehicles he piloted. His family had a full machine shop on their property in Texas, and it wasn’t long before John learned the ropes: feed rates were as familiar to him as algebra, Bridgeport was as common a brand as Ford, and he swapped machine tool cutters as adeptly as he could tie his shoes.

Perhaps even more important than the skills Rader learned in that machine shop was the belief he picked up from his father that it was only a lack of ingenuity and creativity that impeded the march of technological progress. Cars could always be faster, structures could always be lighter, and “good enough” was never good enough.

Tinkering wasn’t a hobby — it was a duty. And so it was that Rader later came to find himself looking at the front end of his mountain bike, unimpressed at the crudeness of what lay before him.

“I was trying to figure out how to make my mountain bikes lighter,” Rader recalled. “I got to looking at the steering assembly and thought that there were all these redundant pieces of metal here. You’ve got a quill going into a steerer tube, which is the smallest-diameter piece of material on the bike, and I figured that it could be made a lot stronger and lighter.”

Instead of using those two nuts and a threaded steerer on his bike, Rader decided that it would make more sense to let all of the components slide freely along the length of a smooth-walled tube. The stem would then clamp directly to the outside of the fork, growing in size and stiffness in the process while also decreasing weight and improving durability. Rader also realized that once the threads were eliminated, designers wouldn’t be limited to heavy steerer tubes made of steel, and could replace them with ones made of aluminum, titanium, or even carbon fiber.

“I came up with the concept, but I didn’t come up with the execution of it for a while,” he said. “I remember waking up one night, rolling over and telling my wife, ‘I got it!’ It was a short duration from there to make the prototypes.”

With physical proof-of-concept samples in hand, Rader was off to the races — literally.

Thirty seconds and a broken office chair

Rader had already made a number of friends within the mountain-bike community, and when he began to map out his strategy for pitching his threadless headset idea to the industry in 1990, California-based frame builder Ross Shafer — the founder and former owner of Salsa Cycles — suggested that he go to the inaugural UCI World Championships in Durango, Colorado, to speak with Dia-Compe USA.

The U.S.-based division of Japanese component giant Dia-Compe, Dia-Compe USA had a reputation for being open to new ideas along with the manufacturing, marketing, and logistics muscle to turn them into viable consumer products. Dia-Compe was so willing to take calculated risks at the time that it was even an early partial owner (and U.S. distributor and manufacturing partner) of upstart suspension company RockShox.

Business was booming.

“We were there in a couple of condos and a significant number of teams from around the world were knocking on our doors,” recounted Peter Gilbert, who was then Dia-Compe USA’s west coast sales manager. “It was a pretty exciting time and really, really busy. It was clear [to the racers] that if you didn’t have suspension, you were really going to struggle. This was a game changer. And in all that frenzy, John Rader shows up.”

Gilbert described a frenetic scene in those days. Racers were practically begging him for forks, and it was all Dia-Compe USA could do at the time to keep up with demand. Given that atmosphere, Gilbert rightfully wasn’t counting on being blown away when an unknown amateur inventor/designer randomly showed up at his pit area, but he entertained Rader nonetheless.

“I’m pretty busy here, I’ve got all these pros lining up,” he recalled saying to Rader. “But I can get you past the gate. Whatcha got? I’ll give you 30 seconds.”

Rader arrived at the meeting with his titanium mountain bike in hand to use for a demonstration for what he had coined the Light Set.

According to Gilbert, Rader undid a couple of bolts, dropped the fork out of the frame, and then put it all back together again, all within a minute or two — a feat that wasn’t possible with the threaded headsets that were being used at the time.

Gilbert admits that he wasn’t able to devote as much attention to the meeting as he might have otherwise, and after exchanging pleasantries, Rader rode off without Gilbert giving the meeting much more thought. But once the dust of the day had finally settled, he couldn’t get Rader’s concept out of his mind.

“Later that night, I was thinking, ‘How in the hell did he do that?'” he said. “With a couple of bolts, he dropped the fork out, slid it back in, and then actually rode away — something was working there, and it was interesting. So I found him the next day and said, ‘John, could you show that to me again?'”

Gilbert wasn’t an engineer or designer, but he had spent enough time in bike shops over his career and had had enough poor experiences with conventional threaded headsets to know that he was looking at something truly groundbreaking. After that second meeting, he called his co-workers at Dia-Compe USA.

“Guys, I’m looking at something really freaking cool,” he told them. “It just shouldn’t work, but it does.”

It wasn’t long after that Dia-Compe USA became the exclusive licensee of Rader’s threadless headset design, helping to finalize the initial patent paperwork, and then later changing the “Light Set” name to the “AheadSet” moniker that is still in use today.

As cool as the idea was, Rader’s invention wasn’t quite sufficiently refined to be sold as a consumer product. In particular, there remained the challenge of how to precisely preload the bearings without introducing more complexity to the system.

Dia-Compe investigated several possible solutions. One required tapping the inside of the steerer tube so that a threaded preload cap could be used. Another idea featured a separate threaded insert that was secured inside the steerer with a dowel pin. But neither offered the elegance that everyone involved was hoping to maintain, nor did they fully retain the promised advantages of Rader’s original concept.

And then one of the wheels fell off of product manager Doug Beeler’s office chair at Dia-Compe USA.

“As the story goes,” Gilbert said, “Doug’s got his chair upside-down, he’s looking inside the leg where the wheel goes, and he sees this star nut in there — and so, hence, the star-fangled nut was born. This became the preload [device], which eliminated any need for threads whatsoever.”

It wasn’t long afterward that the design was fully finalized and headset issues that were once commonplace were, by and large, wholly eradicated from the cycling world.

“The headset can’t come loose,” said Gilbert. “Other things can happen, but the reality is that if the cups are pressed in, you preload the bearings, and you tighten the stem, it is not going to go anywhere.”

Putting all the pieces together

Coming up with a revolutionary product is one thing; turning it into a commercial is another entirely.

Dia-Compe’s relationship with RockShox would turn out to pay huge dividends in this respect, as the company could offer turnkey solutions to its OEM customers. Whereas threaded forks had to be made in multiple lengths (and then still often had to be cut to fit), Dia-Compe USA could offer RockShox forks that were already pre-cut to exactly the required dimension and with the star nuts already installed.

In addition, those forks could be easily bundled with threadless headsets as a package deal — Dia-Compe USA was the exclusive producer of AheadSets, after all — and while the company didn’t manufacture stems (something Gilbert looks back upon as a missed opportunity), it was easy enough to refer bike companies to several suppliers that did.

“Once people got a chance to really start seeing it, it was a very tangible feature,” Gilbert said. “It was definitely quicker to assemble, there were no threads on it, it worked. There were some things you couldn’t do as easily — you couldn’t easily raise and lower the stem — but on the mountain bike side, they didn’t care.”

According to Gilbert, sales in the first couple of years were modest in terms of absolute quantities. Suspension forks were very expensive upgrades in those early years, and even as easy-to-sell, preconfigured bundles, annual OEM orders were in the hundreds, primarily spearheaded by mountain-bike brands like Norco, Rocky Mountain, and Raleigh.

Bigger brands were quick to follow — including GT, Trek, and Specialized — as did the road market once the more tech-savvy players realized how much weight could be saved.

Much has happened since then.

Dia-Compe USA eventually became an independent entity separate from Dia-Compe — turning into Cane Creek. The company’s original patent recently expired, and those little trickles of initial OEM orders now number in the millions. Threadless headsets are now the overwhelming standard, and you’d be hard pressed today to find a threaded headset on anything outside of a big-box store, a cheap kid’s bike, or one of the vintage machines being pedaled around at L’Eroica.

Gilbert is still at Cane Creek today. His office looks out at the same hillside in Fletcher, North Carolina, as it did years ago, and he still remembers the watershed moment when he realized that threadless was here to stay.

“I was at the Taipei show, and I was having a conversation with Frank Scurlock when he was still working for RockShox. And he goes, ‘Hey, Pete, I just want to let you know that, this year, if people want a threaded fork, there’s going to be an upcharge.’ And I just went, ‘Yes — we are done! The game is over. We won.'”