GrayJay

In early 90's tubing supplier Columbus was fabricating and supplying complete unicrown forks that some frame manufactures used. They had columbus stamping on the drop-outs and on the fork steer tube (hidden when fork installed in frame) but no other markings. Though they may look like they came off a MTB, these unicrown forks were slightly lighter than similar lug/crown construction forks so appealed to steel frame weight weenies (when that was a thing). Along with then latest advancements of thin-wall higher strength steel tubesets (such as EL-OS, Genius, Spirit) which surpassed the older unhardened Cr-Mo metallurgy tubesets (like SL,SP, SLX, Max), the unicrown forks helped keep steel bikes a bit more weight competitive with alu/titanium/carbon frames. The Columbus supplied unicrown forks were TIG welded, probably was easier for existing lug-frame manufactures just to use the complete unicrown forks rather than intermixing TIG welding to their shop.

I received one of the Columbus unicrowns on a EL-OS tubeset bike that I bought new in 1992. First one I had cracked along the TIG welds within about 1 year use, warranty replacement fork that I received is still going strong today though the original chrome is in terrible shape. The one other complaint I had about those forms was that they had tight tire clearance would only take somewhere around a 25mm tire, when I tried using with some larger tubular tires I had problems with the tire contacting and rubbing the underside of the fork when it flexed while riding.