Matter is anything that has weight and occupies space.
To prove that a bicycle is a matter, we need to show that it has weight and will occupy space.
When you put the bicycle on a weighing scale, you will see the weight of the bicycle. This a proof that bicycle is a matter.
To show that the bicycle can occupy space, place the device in a tank full of water. From the tank, the bicycle will displace some water. Substances that cannot occupy space will not behave in such manner.
