LUGS. The Good, the Bad and the Ugly

9 03 2009


No, not that Good, bad and the Ugly..  What we are talking about here is Lugs.  The kind we use to construct bicycle frames.   Like this:


Basically a pressed or cast fitting that is joined together using a brazing material (soldering is below 800 degrees-brazing is above.  same concept) which is typically either a form of bronze or high silver bearing material.

Lugs used to be all formed by a method called pressing.  Leviathans of steel and leather belts used to be able to stamp these out by the millions back in the day.   The results, straight from the box were really rough.   Compare the above picture to the example below:


See how they are a lot courser?  The interiors often do not fit as well, there are lots of surface flaws, the edges are jagged  and certain items like seat binders need to be re-enforced to work well.   This is why many feel that the pressed lug is the epitome of the framebuilders art.   When you see a beautifully executed pressed lug you know that a lot of time and care went into it by default.  I submit into the record exhibit A…by Brian Baylis


Later came the investment cast lug.  Just as a wedding ring is made by making a wax replica first from a mold, the cast bicycle lug is made the same way.  This results in a near perfect lug straight from the foundry.  Certainly this was a step in the right direction.  It reduced costs and brought up quality almost overnight.   With all things though there was the downside.   That is that it really does not take the same amount of craftsmanship to get excellent looking and performing results.   Today,  many builders take the lug, straight from the box and with 5-10 minutes of prep work turn it into a reasonable looking joint.    I sometimes call this “fake art”  like the example below:


99% of all buyers would not know that the lug came this way.  See how crisp the lug edges and details are?

So, what in today’s work constitutes a well crafted lug?  All of us framebuilders are capable of brazing reasonably well.   But I look for a little more.

1st.   Clean crisp edges that show no overflow of brazing material or that the builder took the care to clean up any issues.   Perfection would be a perfect 90 degree angle from lug edge to tube/lug edge.  Impossible, but that is what we are shooting for.

2nd.  That the shorelines of the lug flow well.  As delivered from the factory the curves and such do not always flow really well.  Simple filing and modification of the lug edge can do a lot here for visual flow.

3rd.  That the lug is partially thinned.   This is where the lug thickness is reduced to some degree.   Usually the lug is about 1.5mm thick from the factory but thick can make for a heavy looking lug, especially if any artwork has been added the tips become very heavy.   There are a lot of thoughts about how much to thin them.  In the old days, some would thin them until the tip became part of the tube again.   This may be going overboard but some thinning indicates care.   It does not take long to at least thin the tips of the lug.  Thinning an entire lug can be very laborious, but I at least look at this little touch.

4th.  The truly handmade lug.  This lug does not start as a pre-cast piece or a pressed piece but is made entirely by hand by many methods.   This is the pinnacle of our art.   There are many different ways to accomplish this, all of them massively time consuming.  The Glenn Erickson, Richard Moon, Art Stump and Dave Bohm/Bohemian lugs below are all examples of this art.   Rare as hens teeth, always has been, always will be because literally the amount of people on the planet who can do it can be counted on both your hands and it takes a very special customer or desire to do it.

Some examples below of really great work:

Lastly,  The art of it.   Everybody has a different take on this.  I see the beauty in a simple single curve lug done well or a very ornate lug, also done by hand and unlike any other.

It is important as a creator of things to experiment and open yourself up to the possibilities.   Even the most strict of disciplines like Japanese sword making allow for creative outlet through the ornamentation of the scabbard and hilt.   Any framebuilder who professes to it being only a “machine” is fooling themselves.   Why put a snazzy paint job on only a tool?  or add headbadges etc, if the rest doesn’t matter?  Creation is a human need, Expansion of ones self is a human need.  That is how I see it.




8 responses

1 06 2009
Lovely Bicycle!

I can’t look at these and stay calm — they are so, so beautiful. Thank you for this article and gorgeous photos!

4 02 2010
Chris Parks

I have two questions about lugged frame construction.

Is induction heating a better method for brazing than flame? We use induction heating for brazing fittings at work and it seems to be a much more controllable, cheaper and safer method.

If I make minor changes to geometry, such as trimming 0.5″ length from the down tube, can the same set of lugs be used? How flexible is the tolerance for angles in the lugs?

12 06 2010


6 08 2010

Hi! I am a metalworker interested in learning how to braze and shape lugs….do you know of anyone? anywhere? any book? that I could use to learn? Thanks!!! – P

10 08 2010

The techniques used to shape lugs are those that are used in general jewelry work. Most of my learning in this comes from various community college courses taken as audit.

With that said, there are not any books specific to shaping lugs but the Paterek manual is pretty much the beginners bible of framebuilding and there are courses that teach framebuilding. Small pitch. I too give courses to build frames.

Bohemian Frame School

10 09 2012

Love it! Lugs have always excited me from the time I first looked at a very young age. Thank you for a wonderful post.

27 01 2013

The reason why you should thin the edges of the lug is not for looks, but to reduce the stress riser on the tube. A rigid sharp point can cause fatigue over time in the metal from over-stressing it at that point.

28 01 2013

Welderwort. I agree that thining a lug was not only done for aesthetics but also to reduce stress. Thing is over my entire carrier I have rarely if ever seen a failure due to the thickness of a lug to tube issue. I have seen issues with very sharp points that should be rounded out (under the DT, HT etc). I do it anyways. If it helps, all the better but I am not convinced it is at all necessary.

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