CD Lefty forks use a bespoke hub/axle. In a traditional fork/hub arrangement, the spindle only takes some shear and a tiny bit of bending load, where in a lefty config, the wheel alignment is directly determined by the bending stiffness of the spindle. So lefty hubs feature a conical spindle with a larger bearing on the fixed/brake disc side.
Milling a Lefty-compatible axle should be simple enough. You also need a slotted IS brake mount, because the caliper has to come off before the wheel. Biggest challenge is to make sure your FEA is up to scratch (computer-generated or eyeball).
I gotta say though, for all the design and engineering skill required for those two English forks, they’re sketchy at best. They both use calipers (BB7 and XT) with one of the mounts cut off and then they’re bolted on through the hole that normally holds the caliper halves together. On the green roadie, the cable run from the fork is really compromised and the mounting looks pretty flexy too. IMHO, brakes are not something to screw around with. I’m no expert and they are both probably fine, but why force yourself to design such “interesting” workarounds just so you can have a right-sided fork?
Also, have a browse around the work of Mike Burrows. Mostly using drum brakes, but later with disc. He was a great advocate of single sided forks, both in his own work and also his consultancy/prototyping for Giant.
Holy cow, now that is an axle! These are all awesome. It will be a while- if ever- I give a single sided fork a try but I love seeing what folks have done.
Those Mike Burrows designs are really inspiring, great stuff.
Clearly a one-sided fork requires some form of reinforcement in areas like the crown, fork legs, and dropouts. Are there some general design principles that can be applied here, or is this something best left for someone with an engineering background who knows how to do the appropriate calculations, use tools like FEA, etc.?