Welcome to my Instructable on designing rotor guards for bicycles with disc brakes! This design is a simple, flat component which can mount to your fork using the quick-release skewer. I will include notes for other types of attachments, such as bolt-on axles, thru-axles, and others. Rotor guards are useful for protecting your brake rotors from debris, accidental contact, and from balls on the polo court! By mounting a rotor guard, you can protect your rotors and add a splash of color or style. Instructions are written using TinkerCad, but if there is interest I can write up the process for my models from Solidworks.

Supplies

Tinkercad or Solidworks to model

Any material for 3D-printing (impact resistance and UV resistance should be considered)

Any material for milling or laser cutting

Step 1: Size Your Blank Plate, and Add Mount Hole

For a 160mm rotor, I set the diameter of this disc to 180mm. The thickness will depend on the material you plan on using- 5mm is a good target, depending on application. To add the hole for your mount, generate a hole cylinder with diameter slightly larger than that of your skewer. Quick release skewers are generally 5mm, so I set this one to 5.5mm. If your tool has a higher or lower tolerance than .5mm, feel free to adjust this value. For any other kind of mount, like thru-axle, measure the diameter of the axle and size the mount hole accordingly. The align tool in TinkerCad is useful for centering this hole- select both shapes using shift+left click, then select the alignment tool in the top right of the work space. Click on the middle black dots to center the shapes along that line to eachother. When done, select both shapes using either shift+click or dragging a box with left click and select group in order to remove the hole from the solid disc.

Step 2: Add Shaping Cutouts

To ensure the rotor guard doesn't overlap with the brake caliper and fork, around one quadrant of the guard must be removed. The red components pictured will be shaped, converted to hole generators, then grouped with the disc to accomplish the desired shape. Avoiding sharp lines may reduce stress points and improve aesthetics. The easiest, but not necessarily most efficient way to do this in TinkerCad is combining multiple hole generators to cut out a solid, then convert the shape to a hole generator for use. After the initial quadrant is removed, a crescent, rectangle, and half-washer hole generators will give a nice wing shape to the front of the guard.

Step 3: Now Customize!

To the blank disc, you can add designs, lettering, logos, mottos, etc. Match the pattern to your brake rotor, or represent your local riding group, or get creative with the sketch tool shape generator in TinkerCad!

Step 4: Bring It Into the Real World!

I don't have access to a 3D-printer or mill right now, so I made this stand in guard using a plastic plate. I also don't have my disc brake bicycle built, so in lieu it is mounted to my rim brake fork. You can see where a disc brake caliper would sit, and how the guard is mounted on the quick-release skewer. Thanks for reading my instructable, leave comments if you have any questions or want to share ideas for improvements.