Pass the Torch is a concept I’ve been thinking about for some time. Its intent is to allow frame builders to share stories from their workshops. Whether it’s technique, random thoughts, or even, as in this case, production procedures, Pass the Torch will (hopefully) be a great, well-rounded resource for builders and nerds alike (myself included).
The first person to contribute is Mitch Pryor from Map Bicycles. Mitch creates some of the most elegant randonneuring frames and he documents his process with apparent ease. It’s not easy for frame builders to take the time to photograph their work, so I appreciate the time and energy Mitch puts into doing so.
These 3D printed lugs caught my eye and prompted me to reach out to Mitch and ask a few questions. Read on below and in the Gallery captions, as Mitch discusses a recent development in lugwork for his Randonneur Project.
Words and photos by Mitch Pryor
The laminate process is unique in that it allows a LOT of options in joinery and a more modern aesthetic than a casting, in my opinion. With the bi-lam, you not only get total flexibility of joining tubes of any size at any angle, but you get a very clean look with a traditional feel, and more personality than a straight fillet.
When I started doing the Rando Project, I was using lugs and building all those different sized bikes using the same castings was not ideal. Fit up has to be just right for everything to turn out spot on, and I wasn’t happy. It was a fight. Inspiration to try the bi-laminate approach came from looking at pictures of the French constructeurs tandems.
Here is where they had the same problem as me – no lugs would work. I made the switch to this approach in 2010 and have been doing it since. It’s a lot of work for style, so it costs, and that’s why I started working with Steelman on the S&P frames. It’s been working out great, but the urge to complete the look of a lug of my own design has been hard to resist.
That’s where Jono came in. Since I work primarily with physical things, it’s been hugely helpful to be able to model different design possibilities with Jono’s help. The 3D printed lugs you saw are what we arrived at over the past year of fooling around and tweaking the design. With the 3D samples we can actually miter tubes and set up the fixture as if these are actual lugs, to check angles, fit, and proportions.
3D printing makes it easy to dream, but reality is that tooling for the casting molds, and required minimums, make turning these laminates into investment castings very cost prohibitive to a company of my size. I’m planning to do the extra work of building with them as two laminates for now, fillet-brazing them together and then silver-brazing the frame, until I’m convinced there is enough reason to pursue a new casting.
Maybe a Kickstarter approach marketed to the framebuilder community to gauge interest. We’ll see.
Follow Mitch’s work at the Map Bicycles Flickr.