Grade 9 Technology Bicycle Repair is the best textbook app
Lesson 1. Introduction to bicycle repair Lesson 2. Bicycle structure Lesson 3. Principle of bicycle movement Lesson 4. Practice: Oil and grease the bearings Lesson 5. Practice: Adjust brakes , fork collar Lesson 6. Practice: Changing brake lines, brake pads Lesson 7. Practice: Patching tubes, changing tires Lesson 8. Practice: Changing chains, cassettes Review