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Building a better — and quiet! — bottom bracket

Creaks be gone! How and why Ben Farver created the T47 bottom bracket standard.

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Ben Farver wanted to make the bottom bracket boring again.

It was early 2015 and Farver, the founder of the Bend, Oregon-based custom bicycle brand Argonaut Cycles, had just received an email from a customer in Europe. The message addressed an annoying occurrence that has plagued cyclists for generations: a noisy bottom bracket. The customer wondered why the expensive bicycle now creaked like an antique wood floor.

At the time, Farver was preparing to ship another bicycle to a customer in Asia, and he envisioned the future email that was bound to appear about bottom bracket creaks.

“Here I was about to send this bicycle 6,000 miles in the other direction and I know I’m going to be dealing with the same situation,” Farver said. “It was like, ‘This is so annoying. It’s unsustainable. We cannot keep doing this.’’’

Farver’s annoyance centered on a piece of engineering that revolutionized bicycle designs during the last decade: the oversized PressFit bottom bracket. A decade ago the bicycle industry fell in love with 30-millimeter (or bigger) bottom brackets that could be pressed directly into the bottom bracket shell. The new PF30 standard added stiffness and worked with the wider and stiffer crank spindles. Plus, the PressFit design eliminated the chance of catastrophic damage to internal threads. Over the course of a few years the big brands adopted the standard for metal and carbon-fiber racing bicycles, which entrenched the technology across the industry.

But the PF30 standard had one very fatal flaw. Manufacturers struggled to build bottom bracket shells that matched the exact dimensions of the press-in shape. This minor inconvenience, over time, transformed into a major headache. Even if the bottom bracket shell was off by fractions of a percent, the abnormality would eventually create a loud creaking noise. Readers have undoubtedly heard these creaks on group rides and in races—it’s not a broken part or a cracked frame, but rather a bottom bracket shell that is off by a few degrees.

Across the bike industry, builders and mechanics learned quickly that almost every single bike frame had an imperfect bottom bracket shell.

“Frame tolerances are all over the place,” said Jay Sycip of Chris King. “It’s hard to make it perfect, because a [shape] from one manufacturer to another manufacturer, and from one material to another material, is impossible to hold.”

Ben Farver adjusts a T47 Bottom Bracket
Ben Farver adjusts a bottom bracket on an Argonaut frame. Photo: Courtesy Argonaut Cycles

Cyclists, manufacturers, and mechanics learned to live with the PF30 annoyance, opting to treat the creak with grease, sandpaper, or a warranty return. Customers became accustomed to bringing their bicycles in for regular bottom-bracket service, or pulling out the press-fit cups themselves.

But on that day in 2015 Farver was fed up with the creaking, and he decided it was time to start a movement against PF30. Farver longed for the time before 2010 when the lion’s share of bottom brackets were threaded BSA designs that had to be physically screwed into the frame. The design was old and unglamorous, but amazingly simple.

“I reminisced for the days of BSA bottom brackets because of how dumb and easy they were — you set it and forget it,” Farver said. “As soon as we adopted [PressFit] bottom brackets, everybody knew what was in their bike because they had to fiddle with it two times a year.”

Farver had a simple solution: a threaded, screw-in design. Bottom brackets that are screwed into a frame will rarely creak, since the threads secure the machinery in place. So, why not create a threaded design that could screw into a PF30’s 46-millimeter bottom bracket shell hole?

Farver called his contacts at Chris King and discussed the idea. He knew that creating an entirely new part, no matter how small, would require the creation of a new tool to cut threads into a metal bottom bracket shell, as well as the bottom bracket cups themselves.

Apparently, other independent frame builders had expressed similar complaints to the component manufacturer. Independent component brand White Industries and small builder Engin Cycles, among others, had approached Chris King about building a threaded bottom bracket that would fit into the large-diameter shells.

“As it turns out, nobody wants to buy a $6,000 bicycle that creaks,” Sycip said. “And the only way to stop it is threads.”

Detail of T47 bottom bracket partially screwed in to a bottom bracket shell
The new standard proves the innovative power independent manufacturers can have. Photo: Courtesy Argonaut Cycles

But Farver wasn’t inquiring about the part, he was demanding it. So determined was he to pursue the project that he promised to buy all of the new bottom brackets in the first order, simply to justify Chris King building the new part.

“I’ll create the demand to get this off the ground,” Farver said. “If the industry adopts it, great, and if I’m the only one threading these things into my frames, that’s fine too.”

Engineers at Chris King took the concept and ran with it, hashing out the proper degree of the threads to overcome the stresses facing the new part. Farver wanted a 1-inch thread pitch to mimic that of the original BSA bottom bracket. But Chris King engineers believed a steeper pitch of 1.5 would be needed to keep the bigger bottom bracket tight in place. Eventually, Chris King moved forward with the 1.5.

The company worked with longtime partner Paragon Machine Works to produce a prototype, and within a few weeks, Farver had a shipment of the new parts. The new bottom bracket screwed into a threaded shell and worked perfectly, spinning quietly without so much as a squeak. By November of 2015 Farver held an official launch.

“It was a really collaborative effort—it felt like there was something in the atmosphere that people wanted to solve this problem,” Farver said. “I think we wanted to simplify things rather than be a punchline in the joke that is the dysfunctional bike industry.”

Farver and Chris King decided to leave the design unpatented, meaning any manufacturer or builder could adopt it. At first, only small-batch builders adopted the new technology, building steel and titanium bicycles that fit the threaded bottom bracket. But as more time went by, even mainstream brands picked up on the T47 standard. The biggest nod came in early 2019 when Trek produced its Crockett cyclocross bike with a T47 standard. Then, in July, Trek revealed that the new Domane carbon-fiber bicycle would also adopt T47. The adoption meant that T47 had finally hit the big time.

Five years after his big idea, Farver sees the entire T47 project as exemplifying what can happen when independent manufacturers band together to solve an engineering flaw. Sycip agrees.

“Small builders can do something like this because they don’t have massive production schedules that are booked years out or tools that would need to be redone,” Sycip said. “It took a builder to come up with this and launch this idea.”

 

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