If you’ve ever experienced poison ivy or had an intensely itchy mosquito bite, you can sympathize with the way an itchy pet feels when they’re compelled to scratch at themselves nonstop.

It’s a brand that has taken on many, many guises in its 100-plus year history. From the suave, sleek super cruisers that pounded the freshly laid motorways of the 1980s, all the way back to the ...