Part 2 of Zack Vestal’s profile of wheel maker Zipp

Zack Vestal /

Why did it take four years to develop a drill bit?

By Zack Vestal

Zipp Part 2: The drum tests loads wheels with 142 pounds and spins them over bumps at 25 mph for at least 40 hours.
Zipp Part 2: The drum tests loads wheels with 142 pounds and spins them over bumps at 25 mph for at least 40 hours.

Photo: Zack Vestal

Editor’s note: VeloNews Technical Editor Zack Vestal visited Zipp Speed Weaponry’s Indiana factory this spring and reported on the company’s history in part 1 of this article. In part 2, Vestal gets behind some of the company’s philosophy and practices in product development and production.

Zipp Speed Weaponry’s story might be summed up in a tale about a drill bit. During a tour of the facility, engineer Josh Poertner stopped at the spoke-hole drilling station. Holding up a bit, about 3 inches long and maybe a quarter-inch in diameter, he said, “It took us almost four years to design this.”

Poertner told of another tour he guided a few years ago, for SRAM upper management and investors prior to SRAM’s purchase of Zipp. “(SRAM) brought their head composite guy in from Hong Kong, and he didn’t say a word for the whole factory visit. We got to spoke-hole drilling, and he’s watching the drilling, and he pulled out his magnifying glass and looked at this bit, and says, ‘We should buy you for this drill bit.’”

What could be so special about a bit? Poertner effused about the complexities of composites drilling. He talked about the average cost of drilling a single hole — more than $3 or $4 in aerospace applications. He described how this bit was designed using computer models and thermal imaging. It self-corrects for wear, channels carbon dust away, lasts much longer than its predecessors and causes less damage to the composite structure.

There must be something special about a drill bit that took four years to design and 15 minutes to describe, and likewise about a company that supports that kind of effort.

Zipp drills into the pro peloton

Zipp Part 2: Finished wheels are ready for packing after being hand laced and tensioned.
Zipp Part 2: Finished wheels are ready for packing after being hand laced and tensioned.

Photo: Zack Vestal

In part 1, we looked at a progression of Zipp products from the early 1990s to the turn of the century, when Zipp narrowed its focus to high-end road products. Since then, the brand has grown by leaps and bounds.

The thought process and determination that pushed Poertner and Zipp toward their special drill bit pushed the brand to the forefront of deep section carbon wheels. The company pushed to make its products lighter, stronger, and more aerodynamic, developing more and more of its own machinery and tooling.

Seven or eight years ago, carbon wheels were reserved for team leaders. These days, deep-section carbon wheels are virtually ubiquitous in the professional peloton, and it was Zipp that pushed its sponsored teams to adopt the wheels for everyday use, by every rider.

“We showed (the teams) power and energy consumption data proving that everybody, even the domestiques, needed aero wheels,” said Poertner. “In fact, the data showed that especially the domestiques needed the aero wheels since they were effectively doing individual TT’s off the back to fetch bottles, sitting in the wind for the team leader and driving the front to reel in breakaways.”

Now head wheelbuilder Nic James hand-builds about 1,350 wheelsets annually to support all the sponsored teams and riders, many of which purchase wheels at a reduced price.

Zipp Part 2: Head wheel builder Nic James builds around 1350 wheels annually for Zipp-sponsored pros.
Zipp Part 2: Head wheel builder Nic James builds around 1350 wheels annually for Zipp-sponsored pros.

Photo: Zack Vestal


With carbon fiber so commonplace these days, it’s easy to envision giant, faceless machines that work through the night, stamping out flawless carbon bits and stuffing them in packaging. This is the case for some parts, but the human element is often overlooked. However, during our tour of Zipp’s factory, I heard the words “hand labor” again and again.

  • Vuma Quad and Chrono crankarms require 20-40 layers of as many as seven types of carbon fiber, in different orientations, laid into molds by hand. “About an hour of handwork per arm,” said Poertner. “Everything is hand inspected and assembled. It’s just very slow, maybe 15 or 20 cranks per day.”
  • Disc wheels and carbon rims are similarly laid up by hand. For discs, carbon skins are laid over a honeycomb core, using laser guides, in a specific order and orientation, before being molded together.
  • Finished rims are hand-inspected before spoke-hole drilling and lacing. “We don’t paint, but the customer expectation is perfection,” said Poertner. “They can see tiny cosmetic flaws that you and I can’t.”
  • Every Zipp wheel is laced, tensioned, and trued by hand. Zipp rims are not drilled for spoke holes until an order comes in, permitting custom spoke counts and hub selection. “Whether it’s the Garmin team ordering, or you ordering from a bike shop, it’s built to order. In this case, not having machines is a huge advantage. You just don’t get the quality or flexibility without hand lacing,” he said.

The large pool of experienced workers in the Speedway area helps. “We’ve got 15 composite manufacturing companies within 10km of here,” said Poertner. “We have a high retention rate of employees and often we are taking employees (from those other companies).”


Zipp has shown it’s not afraid to push the boundaries of material cost and availability.

For example, a coating on part of the Vuma Quad crankarm assembly is “defense critical,” said Poertner. As raw material, it’s not allowed to leave the borders of the country; it can only be shipped overseas as a finished part. It lets Zipp build cranks “at a weight that no one can even touch,” said Poertner. “It costs an absolute fortune. But that’s really the secret here … that and handwork.”

Material control at the factory is exceptionally tight. Case in point: Raw, pre-preg carbon fiber arrives frozen in sheets or rolls, and is stored in a giant walk-in freezer. Any heat (including ambient air temperature) begins to cure the epoxy, so most carbon has an “out life” of up to several weeks. But at Zipp, material is brought out of the walk-in on a “just in time” basis, moving from raw carbon to finished product in less than a day. Any longer, said Poertner, and “it looks less good, there’s less flow in the resin. But mainly for us it’s a matter of controlling the whole process.”

Steps like this are critical because the company does not use filler or paint to mask flaws. “Carbon parts generally don’t look great raw, and what other companies do is use black Bondo to sand and fill everything before painting,” said Poertner. “Bondo can cover cosmetic flaws that may also be structural … a part that may be filled and painted over in another factory is sent to the trash heap here.”

Tooling and machines

Composites manufacturing is not possible without sophisticated tooling and machinery, and again the drill bit stands as an example. Zipp has designed and built its own machinery and tooling, which often is very exotic — and very expensive.

Zipp Part 2: This giant autoclave is where specific pressures and temperatures cure disc wheel moldings over a multi-hour cycle
Zipp Part 2: This giant autoclave is where specific pressures and temperatures cure disc wheel moldings over a multi-hour cycle

Photo: Zack Vestal

A few examples:

  • The Sub 9 disc requires a tool that pressure-molds the honeycomb in the center, but has a bladder-molded part at the outer. The tool has to be super thin to fit in a vacuum table, and then execute very specific temperature and pressure regimes. “That tool is around $35,000 to $40,000 and it can make one wheel per day,” said Poertner. Zipp has 12.
  • The Vuma Quad crank requires a specific mold and carbon layup for each of its five crank lengths. A custom-made fixture works for all the lengths. “In Asia you’d have one crank length and drill the (pedal) hole in different places … and you’d have different machines and different operators doing each operation. Here, we can have the whole operation computer controlled so there is one machine and one operator running the CNC and doing (quality control) at the same time. The downside is that you’re talking $60-70k for the fixture.” The CNC machine is another $200,000.
  • Each rim profile requires its own tool, including different tools for clincher or tubular options. A row of molds nearly fills one room.
  • Aluminum clincher rims require a wear indicator to pass CEN standards. Most companies anodize the rims, then post-machine a wear indicator, but this interferes with bond prep. So Zipp bought wheel-turning lathes, the same as would be used in the auto industry to machine aluminum wheels. The tool machines the aluminum without cutting the carbon under it. “The machine comes in, finds the wheel, comes up with a strategy for machining, spot-drills the indicators, paints them with a little jet, and then machines the sidewalls. As far as we know it, there’s nothing like it in the industry,” he said. Cost for the machine? A cool quarter-million, plus $100,000 in tooling.

The cost of these machines and tools is nothing short of exorbitant, but it permits Zipp a level of creativity, control, and ownership. “We really benefit from not being in Asia … it allows us to get a lot more creative in the development side,” said Poertner. “It allows us to take something that no one has seen or thought of before, and just go with it.”

Zipp Part 2: Many machines at Zipp are custom built, including this fixture which post-machines all the crankarms.
Zipp Part 2: Many machines at Zipp are custom built, including this fixture which post-machines all the crankarms.

Photo: Zack Vestal

“The good part is that you know every detail of it but the bad part is you are stuck with it for the years it’s in process!” he laughed.


The final production steps are equally expensive. There are tests to satisfy the domestic Consumer Product Safety Commission (CPSC), other tests for the European Committee for Standardization (CEN), and still others for the Union Cycliste Internationale (UCI).

“The amount and cost of testing and certification is astronomical,” said Poertner. “It’s about $100,000 to certify a new (wheel) model, across all the tests, plus whatever we spent internally in testing (during development).”

Some of the tests we saw:

  • A drum test, in which wheels mounted on “forks” are loaded to 142 pounds at the axle, and spun against a 1000-pound drum at 25 mph. Bars on the drum simulate bumps. Wheels must endure 40 hours of this treatment to pass the standard.
  • An impact tester raises a weighted sled higher and higher, crashing it down against the part until it breaks. This is done to measure rim failure energy and perform a UCI impact test.
  • A braking performance test involves dragging brake pads against a rim mounted to a flywheel driven by a large motor. The CEN standards require a certain level of brake performance in wet and dry conditions, at applied loads that simulate a 220-pound rider descending at 50 mph. Thermocouples in the brake pads measure the heat generated. Load cells measure applied braking force, pulsation and force at the brake lever. CEN standards recently went up 30 percent and Poertner said very few carbon rims pass the new test, which means they can’t be spec’ed on new bikes in Europe (although they can be sold as aftermarket products).
    Zipp Part 2: The brake performance test at Zipp spins wheels and applies braking force to measure heat, force, and any pulsation
    Zipp Part 2: The brake performance test at Zipp spins wheels and applies braking force to measure heat, force, and any pulsation

    Photo: Zack Vestal

    The bigger issue is brake heat, which can soften the composite resin. “We were by default the first guys to get this brake heat issue figured out because we were the first to make a really light rim. We were busy solving that problem before others knew it was a problem,” said Poertner.

  • A CEN crankarm test applies 450 pounds of load to each crankarm, pulling on hardened, quarter-inch 4140 chromoly pedal spindles, for a minimum of 100,000 cycles. The special Pedal spindles usually fail after 40,000-50,000 cycles (a standard pedal spindle typically bends or breaks in the first 10 cycles). A computer tracks every load cycle and records changes in displacement (which would signal a pending failure). The cranksets often last more than 200,000 cycles.

Any time something changes — a new model or a running change to an existing model — it has to be re-tested and certified.

Going forward with SRAM

SRAM purchased Zipp in November of 2007. Not much has changed. The company has continued to grow and push limits in design and materials.

The much larger company has brought added resources, but “we still operate off a much smaller company model, where every person wears lots of hats,” Poertner said. “I think that gives us a lot of advantage in certain parts of our market where we can move and react really quickly.”

Zipp’s in-house design, engineering, production, marketing, and customer support are unusual in the US bike industry.

“The flow of ideas for products can make it through the building in minutes, and when the market demand for product changes, we just change what we’re making,” said Poertner. “There is never a wait for some boat from Asia to get a set of wheels.”

The pace of development keeps accelerating. In 1999, after Andy Ording bought Zipp from founder Leigh Sergent, the company was based on four products. In the previous 10 years, the 404 rim was modified just once.

By contrast, in the most recent 10 years, Zipp has brought six shape changes and 10 structural changes to the 404. The average life cycle of a product is now two years. Since the company re-introduced hubs in 2002, there have been four major model changes and hundreds of revisions.

“Nobody here is a super genius or anything. We’re just willing to suffer at the highest level for a long time to really get all the details worked out,” Poertner said. “Like the four years to perfect the drill bit … it’s that level of suffering.”

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