These days, the majority of performance carbon and suspension forks are using 1.5 inch tapered steer tubes. As the description implies, the steer tube tapers from 1.5″ near the crown to the standard 1-1/8″ at the top. The tapered design makes for lighter, stiffer forks that are better equipped to handle the additional stress created by disk brake systems now found on many road and cross bikes. To fit tapered forks, frames need to use a larger headtube that has a 44mm inside diameter. This is easily done when building a TIG welded or fillet brazed frame, but for frames designed with lugs the situation is much more challenging—stock lugs for 44mm headtubes simply don’t exist. Since I am unable to buy the lugs, I will be fabricating them from scratch.
Below is a photo of what will eventually become beautifully shaped stainless steel lugs for 44mm head tubes. The boring bar below the tubing will be used in a lathe to precisely bore the inside diameter of the sleeve tubing to exact specifications.