Singer and Co. England Xtraordinary Challenge 1884.
One of the most popular high wheel safeties, the Xtra, was first introduced in 1879. Positioning a rider's mass behind the center of gravity prevented a sudden flight over the handlebar were the front wheel to encounter a pot hole or stone. A front fork having plenty of rake also helped. The rider drove the machine by adjustable levers to the front wheel. This allowed riders of varying leg length to ride the same size wheel.