Chain keeper

thingiverse

This tool holds up the chain of your Bicycle while the rear tire is taken out. It's very useful when you are cleaning your road bicycle. To make this you need an M10 x 1.25 x 100 screw and a spring long enough. Instructions Maybe is better to scale a little bit the model, indeed the 1:1 one fits very tight on the screw, it needs some smoothing.