Spline’s Advantages
• Lighter than square drive (0.3g each)
• Cannot strip (spoke breaks first)
• Aerospace aluminum (2024-T4)
• Nearly impossible to scratch color
• A wrench fit every 60° rather than 90°
• Sleek, distinctive, better, available now
Why Not Square?
Fastener interfaces have evolved since the dawn of mechanics. Square was the first shape for fastener heads and matching wrenches. Square steel nuts were common on machinery of the late 19th through mid 20th century but today hex drive shapes have displaced them. One reason is that a hex pattern offers wrenching access every 60°, while square offers only at every 90°.
Square headed nuts were also known as cut nuts, made by drilling/punching a sheet of steel with holes in rows and columns. Then the sheet was cut in a shear creating strips each with a single row of holes. These holes were threaded and then a second shear cut across the strip making square nuts. The cutting process was often inaccurate and cut nuts were often not square nor the hole centered.
1949 agreements to standardize threads into ISO inch and metric spelled the end of square headed bolts/nuts (except for cycling!) since new and better machinery to make them would have been required. As machine design advances, nuts and bolts must fit in smaller spaces, meaning less room to swing wrenches through a useful angle. The more faces on a nut, the better.
Why Spline Now?
For bicycle nipples, we have a work in process. Square drive has been unchallenged for 1-1/2 centuries. With steel and brass as dominant nipple materials, enough torque can be delivered to build and repair worst case wheels. However, aluminum is fast replacing brass on higher performance wheels, reducing rotating weight and offering a range of decorative colors. Square is wrong for aluminum which is softer than brass. At the very least, decorative anodizing is too easily scratched, even during careful builds.
Stripped and deformed aluminum nipples are common, driving a backlash back to brass. With a spline drive, an aluminum nipple can resist more twist force than ever needed. In fact, a spline nipple fails only after its spoke snaps from the torque. You will never see a spline nipple torque failure. No wonder both Mavic and DT regularly use splined nipples of their own design.
Technically Speaking
To be precise, the drive standard on our nipples is compatible with Spline Drive of the 1990’s. An attempt was made to commercialize splined nipples by entrepreneurs in Southern California. Perhaps their approach was flawed, certainly the industry was not yet ready. They closed up but not before thousands of builders used them with many considering it superior.
Our standard is described in US Patent 5673976. Technically speaking, it's not a spline but, instead a ribe drive. There is no wavy curve to the contour (like Torx). It resembles a freehub body with all driving surfaces meeting squarely. Enormous amounts of metal need to move in order for the drive to strip.
About Wrenches
Available now:
The detail, below, shows the wrench shape. Notice the convex curve on its bottom surface to maximize rim clearance.
This wrench delivers more torque, engages every 60°, and won't slip off the nipple by tipping away (fewer wrench drops). We offer one model in the familiar chromed wire loop, Park-type shape. Other styles will become available during the year. Though we are currently the World’s only source of 12mm aluminum spline nipples, this won’t last for long!
Now is a great time to dive in and enjoy this building option. Sleek, light, smart, and faster to build!
The Golden Nipple
At NAHBS 2016, we made a huge gold nipple from poplar. Below, it takes shape in Jon's MT shop. By now it has been seen Worldwide thanks to journalists and other fans of the unexpected!
Comments will be approved before showing up.
Neil Garber
November 02, 2021
What lubricant do you suggest to use with these nipples? Thanks,