This is a giant tricycle. Obviously.

Photo via Black and WTF, via Sloth Unleashed, which appended the following backstory:

This giant tricycle was a promotional stunt, publicizing “VIM” tires made by the Boston Woven Hose and Rubber Company. In 1895 ten men rode it 37 miles from Nashua to Concord, New Hampshire, to take part in the Merchant’s Week Bicycle Parade; not that it was strictly speaking a bicycle.

The wheels were 11.5 ft in diameter and it weighed 1900 pounds, presumably including the crew. Apparently it terrified all the horses it met, and an advance party was required to throw blankets over the heads of said horses to stop them bolting.