Lugs as strong as welds?
#26
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Well, it's kind of like soldering copper water pipes together. After carefully preping the tubes and pinning them together with the lugs, you heat up the whole assembly with a torch. When the temperature is right, you use molten silver or (more commonly) brass solder to fuse the joint together. I suspect the reason why you don't see more lugged frames being built today is because it's more labor intensive than TIG welding.
I don't know which is actually stronger and I'd argue that it doesn't matter anyway. Both joining methods have been proven to be strong enough.
I don't know which is actually stronger and I'd argue that it doesn't matter anyway. Both joining methods have been proven to be strong enough.
I personally love the beauty of a quality lugged frame and have huge respect for the craftsmanship a high-grade example requires.
Last edited by hydrocarbon; 07-16-21 at 12:29 AM.
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"and lugs are now an unmistakable sign of a handmade frame" hydrocarbon
There are millions of lugged bikes that were machine brazed. The machine provided heat and filler came before the current popularity of welded joints. Additionally some high volume production frames used tack welds between the lugs and the tubes to hold the structure while the machine brazings were done, much like pins can hold a main triangle before brazing.
Lugs, in them selves, prove nothing about the skills or craftsmanship of the frame. Andy
There are millions of lugged bikes that were machine brazed. The machine provided heat and filler came before the current popularity of welded joints. Additionally some high volume production frames used tack welds between the lugs and the tubes to hold the structure while the machine brazings were done, much like pins can hold a main triangle before brazing.
Lugs, in them selves, prove nothing about the skills or craftsmanship of the frame. Andy
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From the middle '80s and before welded frames were laughed at. Any quality bike was a lugged frame bike. Then came computers and robot welders. Bike mfg quickly found out that they could cheaply produce a frame with a robot and save labor costs. Again it is simply the all mighty dollar speaking.
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Since the materials and methods discussed are no longer a mainstay of the current bicycle industry, it won’t be decided here.
But all that is really needed is a search function.
John
But all that is really needed is a search function.
John
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There is an exception, air-hardening steels, an example is Reynolds 853, primarily a carbon, manganese, chrome, molybdenum, silicon, copper alloy which with welding and air cooling forms a fine grain structure giving it improved yield strength and a resistance to shock.
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There is an exception, air-hardening steels, an example is Reynolds 853, primarily a carbon, manganese, chrome, molybdenum, silicon, copper alloy which with welding and air cooling forms a fine grain structure giving it improved yield strength and a resistance to shock.
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This is why the industry has gone to welding for frame construction as much as it has. Welding is strong enough when done properly and can be done so at a lower cost. Andy
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From the middle '80s and before welded frames were laughed at. Any quality bike was a lugged frame bike. Then came computers and robot welders. Bike mfg quickly found out that they could cheaply produce a frame with a robot and save labor costs. Again it is simply the all mighty dollar speaking.
I love this, a 17 year old thread is resurrected like a old one hit wonder coming back to life.
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Unfortunately facts don’t support your anti business narrative. It was the development of affordable tig welders and the advancements in metallurgy which the tubing manufacturers took advantage of and created tubesets specifically for welding. A tig welded frame is as hand made and has the implied quality as any lugged frame.
I love this, a 17 year old thread is resurrected like a old one hit wonder coming back to life.
I love this, a 17 year old thread is resurrected like a old one hit wonder coming back to life.
One more thing------------------if the frame is welded, it is hard to define a really cheap big box store frame from a $10,000 frame.
Naw------------its the money.
Last edited by rydabent; 07-20-21 at 10:59 AM.
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#41
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Unfortunately facts don’t support your anti business narrative. It was the development of affordable tig welders and the advancements in metallurgy which the tubing manufacturers took advantage of and created tubesets specifically for welding. A tig welded frame is as hand made and has the implied quality as any lugged frame.
Last edited by hydrocarbon; 07-19-21 at 12:45 AM.
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Welded frames are cheaper to build than lugged, but that doesn't mean lugged is "better."
Advantages to (TIG) welded include: lighter, cheaper, faster to build, no constraints on angles.
Personally, I like lugged, but the above are real advantages. Not to mention, lugged is limited to steel. TIG is used on steel, aluminum, and titanium.
BTW, very few welded frames are welded via robotics. Most are TIG welded by hand, even in high volume shops.
Advantages to (TIG) welded include: lighter, cheaper, faster to build, no constraints on angles.
Personally, I like lugged, but the above are real advantages. Not to mention, lugged is limited to steel. TIG is used on steel, aluminum, and titanium.
BTW, very few welded frames are welded via robotics. Most are TIG welded by hand, even in high volume shops.
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It must be lugged, to be able to handle this much flogging!
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I...
The bending stress is maximum at the end point of a cantilever. If a tube fails due to cyclic stress, then chances are it fails at the point where it is attached to other tube. A welded joint also has more metal (due to welding bead and butting) just like a lug. Unless the welder left stress raisers (sharp notches) it would be intuitive to reason that a lug will separate earlier in this application since the lug joint is not as strong as a welded one inch per inch. If anything a welded joint cannot be weaker!...
The bending stress is maximum at the end point of a cantilever. If a tube fails due to cyclic stress, then chances are it fails at the point where it is attached to other tube. A welded joint also has more metal (due to welding bead and butting) just like a lug. Unless the welder left stress raisers (sharp notches) it would be intuitive to reason that a lug will separate earlier in this application since the lug joint is not as strong as a welded one inch per inch. If anything a welded joint cannot be weaker!...
Proof? Look at all the very old bikes out there that are lugged and doing just fine. A lot are older than the process of TIG welding steel.
#46
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Steel lugged or welded frames are too retro. Carbon is so...Millennial. Aluminum creaks more than grandpa's knees. The future of bikes is bamboo I tell you. Yep, bamboo butted with carbon lugs, welded steel fenders, boron seat post and a hemp La-Z-Boy saddle.
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But, for a weld you have a total area of the tubing diameter times the weld width (what? 1/4"?). For a lug you have the tubing diameter times an inchof lug or perhaps more. On top of that, you have on a quality build, contact between the mitered tubes and both the tube thickness and the lug thickness (which can be a lot more than the tube thickness). So far more material where it matters. No thinning of steel at the lug or braze border because it never go hot enough to flow, unlike the weld that takes the steel to very hot
Proof? Look at all the very old bikes out there that are lugged and doing just fine. A lot are older than the process of TIG welding steel.
Proof? Look at all the very old bikes out there that are lugged and doing just fine. A lot are older than the process of TIG welding steel.
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Dunno if this has been mentioned, but the geometry of a lugged frame is controlled by the angles of the lugs.
To build a frame that doesn't correspond to the angles (and tube diameters) of available pre-made lugs, you have to make your own.
And of course some builders do just that, for aesthetic reasons as well.
To build a frame that doesn't correspond to the angles (and tube diameters) of available pre-made lugs, you have to make your own.
And of course some builders do just that, for aesthetic reasons as well.
Last edited by Rolla; 07-19-21 at 10:45 PM.
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#49
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Lugged frames were the best method at the time given the materials and technology availability. That doesn’t mean it’s the best currently because it is not, for steel, aluminum or titanium that would be tig welded. The affection for older or retro lugged frame fills a nostalgic need for some people. The sad truth is the classic frames we look back on such as Colnago, Cinnelli, Masi etc. were as mass produced as today’s carbon S-Works, there were tens of thousands produced and distributed around the world.
I think it's great that there are a lot of these high-quality steel frames out there. They were skillfully made and finished using durable, repairable materials instead of being made of fancy plastic shat out of a high-pressure mould.
Composite frames can be extremely profitable, which is why the bike companies push them so hard. I'm personally not that interested in having a trendy disposable bike, though.
Plus the old-school Italian steel frames actually look good.
Last edited by hydrocarbon; 07-20-21 at 02:32 AM.
#50
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Dunno if this has been mentioned, but the geometry of a lugged frame is controlled by the angles of the lugs.
To build a frame that doesn't correspond to the angles (and tube diameters) of available pre-made lugs, you have to make your own.
And of course some builders do just that, for aesthetic reasons as well.
To build a frame that doesn't correspond to the angles (and tube diameters) of available pre-made lugs, you have to make your own.
And of course some builders do just that, for aesthetic reasons as well.
And to be fair, there are even a few decent-looking carbon frames out there, too.
Last edited by hydrocarbon; 07-20-21 at 02:36 AM.