CityBike Book Club: Harley-Davidson Knucklehead – Eighty Years

There’s always one legendary, marque-defining bike from each manufacturer. For Honda, it was the CB750, For Kawasaki it was the H2.

Harley-Davidson made the Knucklehead—officially known as the EL, first sold in 1936. The iconic shapes and engineering of all things we know as modern Harley can find their roots in this bike.

If you were ever curious about all the things—and I mean all the things—that make the Knucklehead what it is, this is the book for you. Author Greg Field gives us a comprehensive walkthrough, down to the production month, of the changes and developments that made the Knucklehead such an icon.

If you’re unfamiliar with the Knucklehead name, it refers to the shape of the rocker box section on top of the cylinder head. Harley has never officially adopted the nicknames that have been bestowed upon their bikes, but The Knuckle was the first.

Harley had produced overhead valve engines before, but this was their first venture into a production twin cylinder OHV engine. Beyond the technological advancements, the EL was the bike that really defined the classical H-D style and those classic lines.

Buy Harley-Davidson Knucklehead

We may have moved forward from foot clutches and tank mounted shifters, but the Knuckle really defined much of what we think of as a Harley these days. The horseshoe oil tank is still used today on the Softail line.

Harley-Davidson Knucklehead is well arranged, systematically detailing the minutia that made the 1936 EL a turning point that established Harley as a cutting-edge motorcycle manufacturer: the specifics of overhead valves, a recirculating oiling system, and the iconic springer front end, and then on to the pre-war era Knuckleheads, wartime production, and post-war production. 

While Knucklehead can serve as a lovely coffee table book, what makes is such an interesting read for an enthusiast like me (I’m CityBike’s resident “Harley guy,” after all!) is the wealth of knowledge and comprehensive technical details presented. In many cases the manufacturing operation changes are documented down to the month.

It’s a great look back to the time when manufacturers were fixing flaws in new designs and able to update the production line almost instantly—back when “failing fast” and learning from it happened in hardware, not ones and zeros. There are breakdowns of oiling system updates, new hardware, dash and instrumentation updates, and Field doesn’t just go into the what, but also covers the why.

There are copious amounts of beautiful, detailed photos, and not just the standard stock photos or picture-perfect museum pieces either. Field went to great lengths to find unrestored examples that are still correct, as well as bikes that have been ridden and show the working updates as flawed designs were corrected in the real world. Scattered throughout are sales flyers from the era detailing Harley’s ad campaigns and marketing slogans.

Even if you’re not a “Harley person,” this book is worth a read. It’s an incredibly detailed piece of motorcycling history that shines a light on the foundation Harley built their legacy upon.

$50. Hardcover, 200 pages, 12” x 9.75”. Learn more and get your own at

This story originally appeared in our March 2017 issue, which you can read in all its original high-res glory here.