from Rookie’s keyboard,
Hello, friends
Today, I am going to compare the two classic ways to make a steel frame – brazing and “lugging”.
But first, let’s start with the definitions of each.
Fillet Brazed Frames
Fillet brazed frames are made of tubes attached via a metal-joining method known as brazing.
Brazing is not complicated to understand. Here’s how it works:
1/The two metal pieces are placed in the desired position.
2/ The area is covered in flux and heated with a very powerful torch.
The flux removes oxides from the used materials, prevents oxidation during the heating process, and ensures a consistent flow of the brazing metal over the contact area.
3/ A brazing rod usually made of brass is melted over the area.
It’s super important to know that brazing is different from welding.
During brazing, the base material doesn’t melt. The area is only heated to the temperature needed to melt the filler rod.
The melting temperature of brass is 1810-1880°F/990-1025°C whereas that of steel is 2500-2800°F/1371-1540°C. (source)
Think of brazing as“gluing” two pieces of metal by melting a metal rod between them. The melted rod is the“glue”.
One of brazing’s strong points is that the tubes are never heated to melting temperatures that could temper their integrity. For that reason, people see brazing as “kinder” to the frame.
Lugged Frames
Lugged frames are brazed too. But they also have steel lugs (image above) which act as sleeves connecting the bicycle tubes.
Each tube is inserted into the lug. Thereafter, the frame-builder heats the area and melts a filler rod (usually made of silver) into the joint.
The flux allows the melted silver to flow underneath the lug and creates a strong bond between the lug and the tube.
The Pros of Brazed Frames
- Freedom
The main advantage of brazed frames is that you’re dependent on fewer variables since you don’t have to fabricate or buy lugs. Also, you can change the geometry of the frame faster and easier.
And that’s why brazed frames are cheaper and available in larger quantities.
- Lighter
Brazed frames have the potential to be lighter (ultimately it depends on the model) because:
a/ The frame does not have lugs adding weight.
b/ The tubes of the frame can be butted more aggressively since the attachment area is smaller.
Frame butting = removing material from the least stressed parts of a tube while adding material to the most stressed sections. The result is a light and yet strong frame.
The tube ends of lugged frames have to be thicker over a longer section. This is required because the lugs cover a greater area of the tube. That area is heated during the brazing process, and if it’s too thin, the torch will burn through it or temper its structure. The extra material adds a minuscule amount of weight.
On the other hand, fillet brazed frames have a smaller contact area and can be butted a bit more aggressively.
- Slick Joints
Lugged frames have elegant joints, but they’re also “prominent” and popping. Meanwhile, the joints of high-quality brazed frames are smooth and seamless.
- No Tube Size Limitations
Lugs limit frame builders to stock tube sizes. Brazing allows you to use tubes of all dimensions.
- Don’t attract dirt
The smooth joints of a fillet brazed frame don’t catch as much dirt and are easier to clean.
The Cons of Fillet Brazed Frames
- More work
A brazed frame takes longer to build due to the extra mitering, brazing, filing, and polishing.
The lugs, on the other hand, greatly reduce the amount of work needed to acquire a good-looking joint. Hence why some people consider lugs to be a “hack”.
The Strong Points of Lugged Frames
- Unmatched Appearance
Lugged frames are quite rare and stand out. Brazed frames are technically rare too, but the visual difference between a welded frame and a brazed one is too inconsequential to the untrained eye.
A lugged frame, on the other hand, catches attention even among the“uneducated” souls out there. The effect is greater when the lugs and the frame are painted by a master.
- Strength
The lugs shield the joint and add support. When all parameters are equal, a lugged frame is a stronger frame.
- Higher Resale Value
Lugged frames are seen as an exclusive product and retain their price better.
- Faster To Build (once you have the lugs)
A fillet brazed frame has to be filed and polished with various tools. Lugged frames require less sanding.
The Cons of Lugged Frames
- Many Restrictions
The lugs greatly limit the frame builder as they“decide” the angle at which the tubes attach as well as their thickness.
If you want a frame with a custom design, you need custom lugs. Those are expensive to buy or make.
As a result, frame-builders are restricted to generic lugs that come with many limitations.
- Weight
The lugs add weight to the frame. (This doesn’t matter in practice.)
- Painting Is Harder
The paint job of a lugged bike is very important. If not done well, the elegance of the lugs will be lost completely. Consequently, the painter has to invest more effort into planning and executing.
Meanwhile, brazed frames are easier to paint because the joints are smooth.
“Ride feel”?
The “ride feel” of a frame isn’t determined by the method used to connect the tubes. The main goal of the joining process is to create a strong frame rather than a frame that feels a certain way.
Most people can’t feel the difference between brazed, lugged, or welded frames.
The “ride feel” of a frame depends on other factors, namely:
- Frame material
- Tube thickness
- Geometry
- Design
- Execution.
What would I choose?
Neither is better than the other. If the geometry, size, and looks of a frame agree with you, get it regardless of how the tubes are joined. And before all, examine the frame thoroughly before paying.
Until next time,
Rookie
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