I am almost done reading Jon Savage's 1966: The Year The Decade Exploded, an impressionistic look at the pop culture of that year in America and England. I've really enjoyed the book, which has had me going back and listening to lots of Motown and the sounds of Swinging London. He makes the point early on that 1966 was the last point where singles mattered more than albums in music. (Well, at least up to that point, since these days albums have been eclipsed, though just as much by streaming as by singles.) For instance, I know the Stones' singles by heart from 1964-1967, but I have little knowledge of their album tracks in that era. Pet Sounds in 1966 and Sgt Pepper in 1967 would really begin to change things, and the acts that had relied on killer singles would take a hit.
The Yardbirds were one of those bands, churning out barn-burners influenced heavily by Chicago blues, but with a youthful spirit and some original touches. (Just listen to the minor-key dirge "Still I'm Sad" for proof.) While Eric Clapton's name is much more well known than Jeff Beck's, Beck's entrance into the band and Clapton's departure coincided with a great leap forward in sound. The Yardbirds would push the bounds of the pop single to its limits, and explore new ground that other rock bands would soon grab for themselves.
"I'm A Man" is the fountainhead of something entirely new, even though it's a cover. The Bo Diddley original is one of his best, a slow-burner with a classic, much copied blues riff underneath it. He was much covered by British beat bands and for the very good reason that his songs have irresistible grooves that even rudimentary musicians can copy. The Yardbirds took it in a different direction, drastically increasing the tempo, giving it a straight, headlong crazy drive, like a train speeding down a mountainside. This version is all untamed youth and amphetamine, and that's before it gets really nuts.
A minute and a half into the song comes one of the most important moments in rock history, the minute-long instrumental break that finishes the song. The guitars get louder and louder and the song gets faster and faster and faster until it comes crashing into a "whomp whomp wha-BAM!" blues ending. It is an exhilarating experience, and it's all over in less than three minutes. Later rock bands would go all the way, extending the breaks and the solos and the jams and making longer songs not meant to be played on the radio. The Yardbirds, recording this in 1965, had not broken that barrier yet, but they had shown the way.
Fittingly enough, in 1966 that band took in hotshot guitarist Jimmy Page, and after one failed album without the departed Beck morphed in "The New Yardbirds." Instead of that derivative name, they ended up going with "Led Zeppelin," and the rest was history. Zeppelin famously did not put out singles, and their magnum opus "Stairway To Heaven" was over seven minutes long (and never released as a single.) Nevertheless, it was the most requested song on 70s FM radio stations. It still gets overplayed on classic rock radio today, decades after mediocre stand-up comics mocked its ubiquity. You won't hear "I'm A Man" on any radio format, but it's the song I'd rather listen to.