In 2009 after a visit and meeting with Dario Pegoretti at his Caldonazzo workhshop Darrell McCulloch (of Llewellyn Custom Bicycles) and he set about on a project for a level top tube lug set that was sized to use XL or Double Over Size (DOS) tube sizes. A lug set such as this did not exist although Darrell had designed and produced the Crescendo lug set for XL -DOS tubes in 2004, however this set has a sloping top tube.
In the back of Darrell's mind was always the concept of an additional new optional seat lug to complement the existing Cadenzia lug set. To facilitate the ease of the build process with a one pass brazing operation for the complete seat lug so the idea is for socketed lug apertures to fit the seat stays. The idea is not new or unique but has not been done with these tubes sizes and also the older designs for OS tubes are missing many practical and aesthetic design elements.
The final motivation came after Darrell's visit to Bespoked 2016: "After many chats at the show and in the evenings over some fine UK ales I set upon the 3D CAD program once more upon on my return to the land down under. I worked on a new method of creating the 3D CAD model using surfaces rather than solids which took some time and effort to learn but this proved to be a very useful technique for this lug."
Darrell spent many hours working out the design in the 3D CAD program:
Then came the 3D printed prototypes to check over the details:
All was sweet and so the final revisions of the filleting was done after discussions with the tool maker. This was just for smoothing the flow of the surfaces for aesthetic reasons.
The new lugs are available directly from Darrell at Llewellyn Custom Bicycles or from Ceeway in the UK and Nova in the USA.
After some minor rework the proving sample castings were ordered. These arrive and are checked over and before the production order was commenced Darrell made a couple of frames with the samples: