The new Boyd Cycling Eternity hubs push bearings and flanges wider than ever to create a super stiff wheel, and the unique stacked axle system helps it roll smoother by effectively disengaging two of the four bearings when pedaling.
Founder Boyd Johnson says the hubs offer the widest flange spacing out there, especially at the front, where there’s 80mm from center to center of the flanges. Out back, he says most hubs have between 50mm and 55mm between rear flanges, but the Eternity hub pushes that to 56.1mm from flange center to center. The driveside flange is pushed to 18.1mm from hub centerline to flange center, which Boyd says is the widest that can be used on a modern 11-speed drivetrain. And it’s all optimized for both stiffness and tension with a traditional lacing pattern.
Those wider flanges create a wider base, improving triangulation. That means a stiffer “pyramid” peaking at the rim, which translates to less rim deflection under cornering loads. But that’s just part of what makes a stiffer wheel, so let’s have a look inside and see what else makes them special…
On both front and rear, the hubs use what’s essentially a thru-axle design, but it still clamps with a skewer. On both wheels, the dropouts are resting on the axle…there are no end caps. This makes the axle as wide as possible, running from end to end, and the bearings are pressed on top and set very wide to make the system a lot stiffer. Shown above is the Boyd Eternity axle on the top compared to a traditional front wheel axle.
“Another benefit to that is when we do the preload over the axle, it makes it harder for water to penetrate the system,” Boyd said. “Which prolongs the life of the bearings and the hubs.”
The image above shows the axle with preload caps snugged up to the bearings. They thread into place to adjust the preload, then a set screw locks them into position. Bearing width on the front hub is 74mm center to center.
Boyd: “The rear hub has 49% of the tension on the non-drive side, making it virtually even from side to side. That’s with traditional, double cross 24 spokes putting 12 on each side of the wheel. Once you get above 59kg of force per side, it’s enough to keep the spoke nipples from loosening, and going much above that doesn’t do much to increase overall wheel stiffness.
“If a wheel builder wants to do “triplet” lacing (8 on non-drive, 16 on drive side), we could make a new shell with an even wider flange spacing that’s optimized for that lacing pattern, but I’d caution that with just eight spokes on the outside, if one broke for some reason, it could ruin the ride home.”