Every Monday, we’ll take a closer look at a detail of our handbuilt bike frames to help give some insight into what makes a Myth a truly custom bike. This is our Monday’s Magnifying Glass series, and you can find a new one every other week here on the blog.
In this Monday’s Magnifying glass, I’ll be showing off our cone tipped stays. Coned stays are exciting because Myth is one of the only framebuilders in the country using this technique. The cone can be found at the dropout end of any of our bikes that use tabbed dropouts. That’s framebuilder speak for a dropout that’s made from a piece of plate, and has flat tabs for welding or brazing the stays to. The problem many framebuilders face is just how exactly to make an open tube meet up with a piece of plate in a clean and functional way.
There are many ways to skin this cat. Many builders use transition pieces that are welded between the stay and the dropout. Sometimes this is actually a CNC machined cone that has been welded to the tube and then slotted. When we “cone” the end of our stays we’re actually modifying the tube itself, and simplifying the transition between stay and dropout in a way that’s strong, aesthetic, and easily welded.
So how do we do it? The stays start life as raw 4130 aircraft tubing, and the cones are hot formed onto the ends. We chuck the tube up in the lathe, heat it up to a malleable temperature, and force a special mandrel onto it that forms the tip into a cone. This is a somewhat touchy and difficult process, and you only have one shot to get the cone perfect on the first try. This step took a lot of trial and error to get just right, and wouldn’t have been possible without the input of Ron Andrews, owner of King Cage (famous for their incredible titanium water bottle cages). Ron had experience doing something similar when he worked for Fat City Cycles in Somerville, MA.
The next step is to bend the stays into the given profile we’ll use for the bike we’re building. This might be S-bent stays for compliance, or straight stays for rigidity, but they’re typically some version of an S-bend stay. See one of our previous MMGs for some insight into Stay Bending: MMG: Custom bent stays.
Next they’re slotted. This is where the simple cone tip really becomes the transition piece between the stay and the dropout. We decide where to slot the cone based on the angle needed to meet the dropout correctly, and where it will be the strongest. Basically some version of right in the middle. Once this is done, the stays get their seat tube miter, and it’s off to welding.
We think it’s hard to beat the slick transition of our coned seat and chainstays to a nice Paragon Machine Works dropout.
One of the reasons for these Monday’s Magnifying Glass posts is to give you an insight into the building process, and show you details that only builders usually pay attention to. Stay tuned for more exciting details of our frames and build process in the weeks to come.