Rixe

When I first stumbled on this, it was about $97.....I was hoping to get a bargain.

Prewar Girder Bicycle Fork 26" Springer Original Custom Motorcycle Whizzer | eBay

I hope someone here got it and makes an amazing BTR with it.

MHF

That's a really interesting design. I love things that are designed with "form following function". I had study them for a moment to picture them mounted up and working.

I've been puzzling in my mind about how to make the readily availible Schwinn style pivot springer function as a girder. I think it would be possible by bridging across from the lower pivot point to the front strut with a solid aluminum block. Clamping around the straight front strut and attaching with a single bolt at the pivot point would stiffen them up and provide a mount location for front of the lower link. Buying another stem, cutting it off and threading it internally would get you a pivot point for the back of the upper link.

You could use something like these.....
Leaf Spring Shackles and Hangers - SummitRacing.com

or these.....
Search Results for lowering shackles - SummitRacing.com

for your links. Not exactly light weight parts, but a lot less fabrication. Add a shock from the rear of a junker department store suspension mountain bike, and your cruisin' with a girder.

MHF

Axel,

Here in the U.S.A. that Harley is commonly known as the "Hummer". It's design was actually based on the German DKW RT 125. The British and Japanese also had thier own versions called the BSA Bantam and the Yamaha YA-1 respectively.

The Hummer actually used heavy rubber bands for springs.

MHF