Exercise 2: sample answer

The hobby horse of the 1810s showed that a rider could balance on two wheels in line by steering the front wheel. The boneshaker of the 1860s added pedals, but on the front wheel. The high wheeler of the 1870s made the front wheel huge for speed, and added tension-spoked wheels and tubular frames. The safety bicycle of the 1880s and 1890s added a chain to the rear wheel and, with the pneumatic tyre, gave the layout still used today (check all dates); later gears, materials and electric assist refined it.