In a former post on the Choppers Magazine July '71 issue, I commented that I thought this was Dick Allen, but it didn't quite match the versions of his chrome frame bike I knew of. After meeting Joe Hurst, I asked him about it and he confirmed it. The other day I looked at a larger scan of the image. If I had spotted the clutch pedal earlier, it would have left no doubt.
Knowing who this is helps, but I always dug this photo anyhow.