You may have heard of a lugged frame. It’s the oldest type of frame, but still one of the best. If you’ve spent any time researching or admiring bikes, you’ve seen lugged frames.
Lugged History
Lugged frames were once considered a work of art. Cyclists waited months or longer for a custom, lugged frame from a master builder. Contemporary lugged frames are found primarily on quality, hand made bicycles that remain true to the art, design and strength of hand-crafted bike frames.
What is a Lugged Frame
A lug is a jacket, sleeve or fitting that joins two tubes together — think of PVC pipe fittings. Lugs can be found on almost any type of frame material including carbon.
Lugs can be almost any shape, as long as they do the job of joining tubes together. Custom bike builders often make their own, but lugs can also be purchased generically. Carbon lugs are glued on. Steel and other metal lugs are typically brazed on.
Lug Advantages
Lugs offer several advantages to a bike frame. They strengthen the joint by adding material to the stressed areas, and distributes the stress over a large area. Since steel lugs can be brazed on at lower temperatures than welding requires, frames have more integrity. Lugs have fully evolved over the years with proven, time-tested technology without any surprises, know exactly what you’re getting geometry-wise.
First Timers
First-time frame builders don’t need to cut precision angles on tubes to make them fit — tubes can be cut off square if desired. Lugs provide more sizing options — if a tube is too long, slip it off the lug, trim the tube, and reassemble, making tiny adjustments until it’s perfect.
Lug Disadvantages
Lugs also have distractions as well. They must fit perfectly. The diameter of the lug must match the diameter of the tube. Loose play is not acceptable, and purchasing generic lugs for generic tubes may not always work out. The shape of the lug determines the geometry of the bike — changes in frame geometry are null and void when using lugs. Bike frames made with lugs are stiff, and lugs add weight to a frame.
The Artsy Connection
The lost art of lugged bikes is mostly associated with steel frames. Artists often customize frames with lugs cut into artsy designs, or by using andonized or painted lugs. High-dollar lugged frames are often seen in bike shows.
Lugged frames, although not mainstream, are not forgotten, you’ll probably see more lugged frames at a bike show than anywhere else. And it’s highly unlikely that you’ll see many of them at a bike race. But the lugged frame has definitively earned its distinction in the history of bike frame construction.
