What is this thing?

[Yellowbice]

In all seriousness, this frame was recently donated to our shop here in Austin, TX. Its quite peculiar as it appears to be a belt drive cargo bike. Also, the fork hints that it could've been designed to be an eBike. The biggest mystery, aside from the creator, is the open parallel tubes behind the seat tube, what are they for? A battery? Cargo attachment? The seat tube has one opening, presumably for cable routing, near the bottom bracket. However, there is no opening in the seat tube where the parallel top tubes are. There's also internal cable routing at the front of the frame, but not at the back of the frame. Either the builder forgot some stuff or I am missing something. If you know anything or maybe have some insights I'd love to hear from you.

 

[Pedropete]

Bit of an odd duck isn’t it. Frame builder’s practice piece? Or maybe just a collection of ideas put into practice to see how they worked in the real? Fun to ponder the possible use-cases though. Rear triangle looks too short for any real load lugging. Rocket-assist, perhaps?

 

[simongt]

Inclined to agree with Pedropete, although double top tubes weren't uncommon many years ago. Also observe that the bottom bracket axle appears to be offset on the tube.

 

[Ming the Merciless]

Inclined to agree with Pedropete, although double top tubes weren't uncommon many years ago. Also observe that the bottom bracket axle appears to be offset on the tube.

Indeed an eccentric bottom bracket

 

[simongt]

Indeed an eccentric bottom bracket

Maybe the trademark of the eccentric who built it - !

 

[TheDoctor]

Given that there's vertical dropouts, you'd need some way of setting the tension.