Cartridge bearings are truly ubiquitous in cycling equipment these days, being used in wheels, bottom brackets, suspension pivots, and even shifters and brake levers. Basically, if it rotates, there’s a good chance you’ll find one there.
As you’d guess, most cartridge bearings are made in Asia but Enduro Bearings is bucking that trend, manufacturing its premium XD-15 cartridges from start to finish right in its home state of California. We recently visited the factory to take a look at how it’s done.
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First off, why bother with US domestic production at all? After all, Enduro already produces the bulk of its bearings overseas and Asian factories have proven themselves time and again of not only being able to produce very high quality but often at a significant cost savings, too.
Enduro says it’s after the ultimate in dimensional tolerances with its premium XD-15 hybrid ceramic range, however, and there’s a little more wiggle room in terms of manufacturing costs given the high-end retail pricing.
Enduro says it produces its XD-15 hybrid ceramic bearing range in small batches in the US because it's the only way to ensure the desired quality
“The special 45-degree angular contact [bearings] especially need extra attention,” said Enduro marketing man Chuck Panaccione. “In the final process, they are matched and hand built to the aluminum cups they are seated into. Heat treatment of this material is more critical than other super alloys of steel, too.”
Enduro sources the raw materials for its XD-15 bearing races from French company Albert & Duval while the silicon nitride ceramic balls come from Cerbec – a division of another French company, Saint-Gobain, which also happens to make most of the composite bushings commonly found in many mountain bike suspension components.
Silicon nitride ceramic ball bearings for Enduro's XD-15 range come from Cerbec, a division of French company Saint-Gobain
According to Enduro, the special nitrogen-infused steel is far more resistant to corrosion than stainless, yet also much tougher than standard bearing steels. More specifically, the steel’s ultra-fine and unusually uniform microstructure is supposedly less prone to pitting over time than other bearing steels.
Not surprisingly, the raw materials are also apparently quite difficult to work with and since the volumes are very low – “orders of magnitude” lower than Enduro’s mainline products – there’s not much motivation to move offshore. Enduro suggests that the logistical complications surrounding the XD-15 raw materials also preclude manufacturing through the usual channels with lead times that can be a year or more.
Now that's hot!
“It is similar to machine as 440C [a common high-end stainless bearing steel] but it wears out the tools quicker,” said Panaccione. “Even though bearing steel is slightly harder, XD-15 wears more evenly and has better resistance to carbide formation that causes pitting in regular bearing steel.”
In addition, the Enduro folks happen to have a long history with the fellow Californians who do the machining work – and they’ve proven to be pretty darn good at it. Machinist Sonny Brunido started working with Enduro more than 10 years ago, first creating a line of high-end aluminum tools for replacing cartridge bearings in bottom bracket cups. That tool line has greatly expanded since then, and these days Brunido works for Enduro exclusively on both tools and components.
Bearing assembly is done completely by hand
The rods arrive from France in hefty 6m (20ft) lengths that are quickly trimmed down to 1m (3ft) for easier handling. These are driven from the company headquarters in Oakland, California down to its machine shop in nearby Hollister where each inner and outer race is individually milled. From there, the bits are transferred yet again to a local heat treatment facility.
There, the races are carefully heated – and subsequently cooled – so as to further harden the exterior surfaces in preparation for a rough life ahead. Afterward, the races are machined again, both to produce the final dimensions and to remove the blackened ‘crust’ that forms from the heat treatment process.
It’s only then that the bearings are ready to be assembled.
Enduro also machines its tools and many of its bearing assembly components in-house
The ceramic balls are first snapped into their plastic retainers by hand, and then grease is applied to the other race. The assembled bearing retainers are inserted, followed by the inner races, and then a retaining ring is installed on the back side. From there, it’s just a matter of hand-testing the bearings to check for noticeable contaminants or binding, and then they’re off to be pressed into bearing cups that Enduro also machines in house.
Such a convoluted and expensive process might seem excessive for such a mundane (and often disposable) component but Enduro’s efforts seem to have paid off. Prior experience has demonstrated the Enduro XD-15 angular contact bottom bracket bearings to not only be one of the lowest-friction options on the market but also one of the most durable we’ve ever tested – so much so that a full winter of commuting on a test sample with all of the supplemental seals removed didn’t produce any damage.
As always, it’s important not to confuse a high price with poor value.
For more information, visit www.endurobearings.com.