Monday, November 25, 2013

For the Love of Lugs

I'm a sucker for a lugged frame. I know that there is a lot of skill involved and a certain industrial/utilitarian aesthetic in a really nicely welded frame, but I never really learned to appreciate it.

A really nice hand-cut seat lug. Note the extension on the
back half of it for the seat stays. 
No doubt, my preference for lugs has to do with the fact that when I first got interested in bikes, the best bikes were nearly always lugged. Until the mid 1980s, welded construction was generally a sign of a cheap bike -- usually heavy, made from mild steel, and probably sold in a department store. This was because the thin-walled, lightweight, high-strength steel tubing used in better bicycles would be destroyed by the heat of welding. Brazing with lugs uses a much lower temperature than welding, leaving the integrity of the tubing unharmed. But with the spread of TIG welding, along with new formulations of steel that could withstand the concentrated heat of welding, more and more quality bikes started showing up without lugs.

Another factor that led to the decline in lugs was the rise of mountain bikes. A lot of riders who came into bicycles through the MTB side of things didn't really care about lugs. Many mountain bikes were welded, and their riders didn't have the expectation of a quality bike being built any other way. By the end of the 80s, mountain bikes had virtually pushed road bikes off the showroom floors. Eventually, when road bikes made a comeback, they looked a lot more like MTBs. Aluminum frames were much more popular too -- and almost always welded. Practically a generation of younger riders came to bicycles without ever seeing a lugged frame.

To me, bicycles should not only be functional, but beautiful. Lugs make for a strong, reinforced joint while also adding a point of visual interest. A skilled and imaginative frame builder can sculpt the lugs to make a frame truly unique and special. Lugs also make a bicycle that is much more easily repaired. A crash-bent or dented tube can be replaced without impacting the long-term integrity of the frame.

Let's take a look at some of the classic production-made lugs that were commonly seen on bikes in the 60s and 70s. These first four examples were made with a stamped method. Stamped lugs tend to be a bit rougher and less consistent in quality, so building with stamped lugs takes much more time and skill to get a good final result than the investment cast lugs that would come later.

Cinelli stamped lugs. A classic, traditional choice in the 60s and 70s.
Prugnat 62 D. There were several variations of the Prugnat long-point lugs. This is a slightly fancier version, with a small scroll-cut detail on the rings at the top and bottom head lugs. The basic "S" lug lacked that extra detail (looking quite a bit like the Cinelli lugs above), while the "S4" had some triangular cut-out windows. These 62 D lugs were used on a lot of classic racers, including Colnagos in the 70s. 

Prugnat 62 S. A shorter point lug, with extra scroll details on the sides. Pretty.
Nervex Professional -- these made the fancier look of hand-cut lugs possible on production bikes and quickly became a favorite. These were the lugs of choice for Schwinn Paramounts, Raleigh Internationals, Peugeot PX-10s, and countless other production racing and sport-touring bikes in the 1970s. In the hands of a skilled builder who takes the time to really clean up the details, these can make an exquisite frame.
The next two lug sets, from the 1980s, were made with the investment casting process, which yields much more consistent results, and making the job of the frame builder a lot easier. A good builder will still take time to file them and thin the edges, and some will even re-shape the contours slightly to a more personalized style or preference, but some less-skilled (or less meticulous) builders might braze these up right out of the box with only minimal filing.

Cinelli investment cast lugs from the 1980s. This version has shorter points, which became more popular in that decade.
Henry James investment cast lug set. Nice proportions all around, and the fork crown is gorgeous. A lot of American custom-frame builders used (and still use) these for a clean-looking frame.
More recently, lugged frame building has undergone a bit of a resurgence, and several American designers have come up with new investment cast lugs that are available to builders all over the world.

Kirk Pacenti designed these "Artisan" lugs, which are designed to be used "as is," or to allow a great deal of expression on the part of the individual framebuilder. There is a lot of room to modify these, and many custom builders have used them as the basis for very special one-of-a-kind frames.
Pacenti Artisan lugs, modified for a 60th Anniversary Mercian. Note that the point has been shortened, and a diamond "window" has been cut out. Sixty commemorative frames were built with this design. Some builders go a lot further with the Artisan lugs, making them barely recognizable from their original form.
Modified Pacenti Artisan seat lug.
Richard Sachs designed these "Newvex" lugs to be an updated version of the classic French Nervex model (the originals being long out of production). The Newvex lug set keeps the classic visual details of the originals, but adapts them for the slightly larger proportions of today's steel bicycle tubing. Also note that the upper head-tube lug has a slightly taller profile, which allows for higher bars -- a useful touch with today's threadless stems.

Lug blanks.
Some builders are well known for completely hand-cutting and shaping their lugs, either starting with something commercially available and modifying it (like the Mercian Anniversary bike shown above), or in some cases, starting almost from scratch with lug "blanks," which don't look much different from the pipe connectors found in the plumbing section of the hardware store. With these, a builder has the full freedom and a blank canvas to make a frame that doesn't look like any other. One vintage builder that was famous for truly intricate hand-shaped lugs is the British brand Hetchins. Some of the Hetchins lug styles are incredibly ornate, as seen to the left.

One current company that still regularly hand-shapes lugs from blanks is Mercian. Their Vincitore model is still made in much the same way as it has been made since the model's inception. Because the lugs are completely shaped by hand, no two are exactly alike, though there is a pretty uniform "pattern" or "style" to the Vincitore lugs. The particular model was introduced around 1964 (according to Mercian) but a similar lug pattern was seen on some Mercians going back to the 1950s.

This is one of my newest bikes, a Mercian Vincitore. This is a pretty good shot of the head lugs 
Another look at the head lugs, from the back.
Functionally, there isn't anything wrong with a welded frame, but certainly don't ask me to pay a premium for it. It can be exceptionally strong and in some cases can even save a few grams (though I believe the difference in weight is inconsequential). And I know that the tube mitering has to be perfectly spot-on with a welded frame because the joint is out in the open -- and if a builder isn't skilled with a torch there's no hiding it, so it certainly takes good frame building skills to do it well. Still, one cannot convince me that it isn't cheaper to weld than to braze with lugs -- as evidence, just notice how almost all production-line bikes (apart from carbon fiber) are now welded -- if it wasn't significantly cheaper to weld, then welded frames wouldn't be so common.

The preparation for lugwork goes way beyond good tube mitering and skills with a torch. There's much more labor involved. Lugged construction goes much deeper than pure functionality. It elevates the function to a more artistic level, and that really appeals to me. It always has.


  1. I am in the enviable position of contemplating a Boulder Bicycle All Road frame. I could save $600 by going for the tig welded vs. the lugged model. But nearing 70 and finally ordering my first custom frame, guess which I'll go for? There's no question. Aesthetics are priceless.

    1. That's definitely the choice I would make -- That should be a nice purchase for you. Enjoy!

  2. I realize this is an old post but it will probably always be relevant to someone. As for me, I just bought a bike from a gentleman in Portugal and the primary reason for the purchase is for the fancy lugs on it. Ideally I can locate someone to possibly aid in identifying the lugs and frame. They look similar to the Prugnat 62 S lugs but I'm not certain. Thanks.

  3. I have 4 Paramounts an dlove the N ervex lugs!