A few reasons why the Buffalo Motor Car is so popular. 1902 E. R. Thomas ad, featuring the Buffalo Tonneau and the Auto-Bi. Aviation Pioneer Glenn Curtiss used an E. R. Thomas motor on his motor bicycle to make several endurance runs.

Hudson founder Roy D. Chapin, Sr. was still with Oldsmobile at this time, and ran an Olds in a 100 mile race in Chicago that year. In 1906, he would join Thomas in founding E. R. Thomas-Detroit, from out of which the Coffin/Chapin-designed “Hudson Motor Car” became the Hudson Motor Car Company.

Here’s a better look at the Thomas Auto-Bi. Rambler and Mitchell-Lewis were also building motor bicycles at this time. The Rambler was known as the Rambler AutoCycle, and the Mitchell was called simply The Mitchell Motor Bicycle.

1900 E. R. Thomas AutoBi

Rambler AutoCycle:

1904 Rambler Motor Bike

Mitchell Motor Bicycle:

1904 Mitchell Motor Bicycle Ad

… I am working on an article right now about a 1902 endurance race involving motor bicycles, including all three of these brands.
-mike The National Motorcycle Museum, in Anamosa, Iowa, has the above photo of the Rambler bike at their website, discussed in this AMC Heritage Forum thread.