1. A brief history of comfort

2. The first bicycles had solid metal wheels
The first bicycles had solid metal wheels. If you cycled on it, you felt every bump in the road.

3. Later bicycles had more comfortable solid rubber tyres.

4. But even these did not make for a smooth ride
But even these did not make for a smooth ride. They were called 'boneshakers'!

5. Solid rubber tyres can change shape a little
Solid rubber tyres can change shape a little. So the rider does not feel the bumps on the road as much.

6. Modern bikes use an even better idea. The tyres are filled with air.

7. The air in the tyre can be squashed quite a lot as the tyre hits a bump.

8. Then the tyre springs back into shape
Then the tyre springs back into shape. This makes modern bicycles much more comfortable to ride.