This, as I’m sure we all know, is a Kettenkrad.
They’re serious money. The one above, restored to within an inch of its life, was offered for $125,000.
The Kettenkrad, or Sd Kfz 2 to give it the official title, occupied that niche, never explored before or since and probably with good reason, of the tracked motorcycle (which is what the full name of Kettenkraftrad means).
But that’s not what I learned.
The machine has a front wheel which seems to be a little superfluous. It doesn’t bear much weight, steering is by differential braking (turn the handlebars and the brakes are applied on the appropriate side) and it was sometimes used without the wheel. So why fit it?
The reason, as per this video with its terrible machine subtitles, is to increase obstacle clearance. The theory is that the front wheel established contact with the obstacle first and assuming the obstacle wasn’t too high it would ride up and lift the rest of the Kettenkrad with it so the tracks could get a grip on the obstacle and proceed. Looking at the picture it seems to me that the front (and driven) wheels of the track section are already as high as the front wheel and should have as good a chance as it does but there you go.
Want to see a Kettenkrad clearing an obstacle? Here you go.