NSU HK101 Kettenkrad.
War forces some unusual designs, like this NSU HK101 Kettenkrad. It first saw service in 1941, and was meant to be a lightweight all-terrain vehicle. It became obsolete with the end of WWII. It steered with the front wheel at lower speeds and with the tracks at higher speeds, and was powered by a liquid-cooled inline four made by Opel. 
Megola.
Back before reducing unsprung weight was a thing, we had the Megola, with its five-cylinder radial engine mounted inside the front wheel. Between 1921 and 1925, the Megola roamed the streets of Germany, its engine shutting off at every stop, and its rider push-starting it at every launch — it had neither transmission nor clutch. Things have gotten better since then. 
Bömerland Travel.
Bömerland motorcycles were made in Czechoslovakia from 1925 to 1939. Looking like a mix between a king-sized Rukus and a Rokon, they were designed to cover long distances. Some, like this 1925 Travel Model, had three seats. This one also had two torpedo-shaped auxiliary fuel tanks feeding its 598 cc four-stroke single. Bömerland was the first bike maker to use cast aluminum wheels. 
Wanderer.
Here’s something I bet you didn’t know: Wanderer built bicycles, cars, typewriters and motorcycles in Germany between 1902 and 1929. A Czech arms company called Janecek bought the licence to Wanderer’s motorcycle designs in 1929, and began manufacturing motorcycles under the Jawa name (JAnecek, WAnderer). 
Husqvarna 180.
Husqvarna has been making motorcycles as long as Harley, though early Huskys were never exported to North America. Like its American counterpart, the Swedish company also made side-valve V-twin engines, This 1928 180 model has a 550 cc, 50-degree V-twin and three speeds. 
MV Agusta Pullman 125.
Today MV Agusta motorcycles are things of beauty. This barn find Pullman 125, not so much. Despite its pedestrian styling, during its four years of production (1953-56) the Italian-made 125 cc two-stroke proved a popular people mover, and sold in the thousands. 
Militaire.
On the one hand this American-made 1915 Militaire represents the technology of the time: wooden wheels, leaf-spring suspension, and a transmission-mounted leather-band brake. On the other hand it boasted contemporary features like an inline four-cylinder engine, shaft drive and hub-centre steering. It also had two additional retractable wheels that a rider could deploy at a stop. 
Flying Merkel.
Flying Merkel motorcycles set records anytime they show up at auctions. This board tracker is probably valued at a gajillion dollars. 
Anzani.
If you’re unfamiliar with the steampunk retro-futuristic genre, one look at this pace bike should set you straight. Back when paced bicycle races on board tracks were popular, cyclists would follow pace vehicles very closely, taking advantage of the slipstream and attaining higher speeds than without a pace vehicle. This 1920 Anzani pacing bike served just that purpose. Ungainly, for sure, but as highly focused in its job description as modern supersport machines.
I have been by there several times and have stopped for a coffee at the cafe even, maybe I’ll have to take some time and check it out next time. Timmelsjoch is a great road also.
How did you manage to pare it down to these gems. Looks to me like there should be a follow up article. Is that an Imola Ducati in the first picture or a replica