saddle up the bone-shakers, we’re riding to iron town

Boneshaker (or bone-shaker) is a name dating from the 1860s for the first type of true bicycle with pedals, which were called velocipedes by their manufacturers. “Boneshaker” referred to the extremely uncomfortable ride, which was caused by the stiff wrought-iron frame and wooden wheels surrounded by tires made of iron.

https://en.wikipedia.org/wiki/Velocipede