Ultimate Headset Spacer for Bikes - Low Poly, Smooth, & Ultralight (Parametric)

The world doesn't need more boring 3D printed headset spacers, so I made some slightly less boring ones. I also made some very boring headset spacers. These are for standard 1 1/8" headtubes, but I've included the F3D and STEP files so you can change whatever you'd like.

• Low Poly variants - 10mm, 20mm, and 40mm heights to match your gaming chair or whatever.
• Smooth variants - 10mm, 20mm, and 40mm heights in an hourglass shape that's more ideal but less interesting.
• Ultralight variants - 10mm, 20mm, 40mm heights with an anemic 1.6mm–2.4mm wall thickness. Only recommend if using high strength filaments properly, and you have an understanding of mechanical bike work.

Printing: Print in a strong, low-creep filament. I like to print these in carbon-nylon, although theoretically nylon can creep a bit. I check my headset occasionally and you should too. Headset spacers are under some compression, so you want no infill and all walls (4+ walls, should have no gaps). No supports needed. 

I print 0.12mm layer heights usually, but 0.2mm and larger should work fine as long as you're tuned appropriately. With some filaments I use fuzzy skin on the outside for a subtle texture (0.1mm point distance, 0.04mm depth). For the Low Poly variants I don't use fuzzy skin in order to give the facets more definition, but you do you.

In general, I recommend measuring how much spacer height you need and printing a single custom spacer at the right height, rather than stacking a bunch on top of each other. It looks better and it's lighter.

Parameters: If you want to make changes, open the F3D file in Fusion 360. Choose Change Parameters in the Modify tab, and update the user parameters to whatever you want. The main variables you'll mess with for is SpacerHeight and SpacerMiddle. The middle defines the shape of the “hourglass”—how the wall transitions from the top and bottom thickness, to the middle thickness (thinner). In general, the shorter the spacer, the smaller a SpacerMiddle you want.

Low Poly: For the Low Poly variants you can adjust the facets by editing MeshReduce in the timeline. The stock setting is Remesh Type: Uniform and Proportion: 10 for spacers with no text. Note: Fusion 360 currently loves to default back to Remesh Type: Adaptive, so if you're struggling, make sure it's set to Uniform.

Text Embossing:

• Roll the timeline back to directly after the Emboss feature (avoiding all of the mesh nonsense that makes the Low Poly versions), then right click>unsuppress it to add text. 
• Make sure that your SpacerMiddle parameter is equal to or greater than TextSize. 
• Set TextDepth for how deeply you want to emboss the text; I recommend ~50% of your nozzle width.
• Customize the text in the Spacer Text sketch. The text size is driven by a User Parameter.
• If you enable text embossing AND low poly, things will get a bit weird. You'll want to go into the timeline and find MeshReduce, then set Proportion: 20 and make sure Remesh Type is set to Uniform. This is a bit messy so good luck.

Weight: The ultralight, weight-weenie variants are ~1.5 gram for a 10mm spacer and ~5g for a 40mm spacer, which is a bit silly. With the parameters above plus SpacerThicknessOuter and SpacerThicknessInner you can lighten it up, or make it indestructible. 

I made a sub-1-gram 10mm variant and ran it on an enduro mountain bike for months without issues. That said, I don't really recommend chasing grams with headset spacers—once you're this deranged you may as well just slam your stem, cut the steerer, and accept your back pain.