Most bikes will have some sort of chainstay protector or chain gaurd to keep the frame from being damaged. When the chain bounces, it can slap against the chainstay and damage the paint. These protectors can fall off, wear out or simply be insuficient to keep your bike in good shape. Here we will make a 3D printed chainstay protector to guard against chain slap.

TPU is an ideal media for the guard as it is flexible and highly resilient to impact and abrasion. It will aslo bend around curves in your chainstay and help accommodate the highly unique shapes of a bikes tubes. A printed TPU stay protector is a cheap and sturdy way to prevent damage to your bike.

Supplies

For this project you will need:

Tools
Calipers
3d printer
Tinkercad or other design software
End Nippers or other tool to cut zip ties
Supplies
Zip ties (2)
TPU or other flexible filament - flexible filament allows you to make a straight protector that will bend to the curves of your chainstay.
A bike!
Adhesive (optional)

Step 1: Measurements

Measure the crossection of the chainstay. My chainstays are .75" round steel. Get the best measurements you can. They don't have to be perfect - the flex in the finished product will allow for some play.

If your chainsay is not round, measure the width and height of the tube. You can modify the outside diameter of you guard to fit any shape.

Measure the length of the area to be covered.

Step 2: Design

In Tinkercad or your favorite design software

Create a hexagon larger than your cainstay's diameter. Here I created a 1" diameter hexigon
Hexigons are great as they provide a nice flat surface to print on and will do not require support material for the overhangs.
Create a bar the shape of your chainstay - for my bike it was a .75" diameter cylinder but if it is rectangular, make a rectangular shape to create the hole in the guard
Group them together to cut a hole through the middle.
Extrude a shape to cut off the bottom of the chainstay - This will allow you to wrap it around the say itself
Cut out the middle section to make ears on either end of the protector
I used another hexagon so chamfer the ends
Export as an STL file

Step 3: Print, Apply, Ride

I've attached the STL for the one I created but I highly suggest you create your own as you can your won flair.

Slice your STL and Print the connector and fit it over your chainstay. I print the guard flat on the print bed, not standing on its end, to help prevent the failure. Printing this way also orients the layers in the strongest direction for this application.

You can apply some optional adhesive to the inside of the protector for an extra secure fit if you want. Since my tubes were round, I used a small amount of spray adhesive to help reduce the chance it would rotate around the tube. It really did not seem necessary but it was available so I figured it wouldn't hurt.

Snap it on your chainstay and zip tie in place.

Cut the cut ends of the zip ties - end nippers work great for this. The cut ends can be sharp so try to have them point away from your leg if possible. You don't want them to scratch your leg in the event you brush up against them.

Cut the ends of the zip ties and hit the trails!