How can I convert a single-speed bike to a 3-speed bike?

To convert a single-speed bike to a 3-speed bike, you will need to replace the rear wheel hub with a 3-speed hub that has an integrated gear system. This will allow you to shift between three different gear ratiOS for varying levels of resistance and speed. Additionally, you may need to install a new shifter and cable to control the gear changes. It is recommended to consult a professional bike mechanic for assistance with this conversion.