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Lugged, TIG, whatever....(15 posts)

Lugged, TIG, whatever....AFrizzledFry
Nov 1, 2002 10:46 AM
what does all this mean? how can you tell teh difference?i'm not very familiar with this aspect of bike technology. any explanasions would be appreciated...

thanks ahead of time...
mainly a matter of aesthetics these daysColnagoFE
Nov 1, 2002 11:15 AM
some people love the look of lugs, but there really isn't much functional difference between the joining methods. Lugs are pretty hard to find on entry level bikes these days so if you're just starting out you're likely to get a TIG bike.
Nov 1, 2002 11:24 AM
Lugged: This is the way ALL good frames were made before 20 years ago (except for those fillet-brazed Schwinn Paramounts..), and are identified as the type where the tubes go INTO a lug at the joints. Used to be the only way to make a light, strong steel bike, but now has been abandoned by all but the most retro manufacturers (Rivendell, Mercian, a few others)
TIG (standing for Tungsten-Inert Gas welding): The most common method for welding steel frames today. Recent advances in tubing technology allow welded joints to be strong without being britle or requiring long annealing processes (which used to make welded frames very undesireable or were too expensive/time consuming for serious bikes) Today, TIG welded frames are lighter, stronger, cheaper, more durable, and able to be made in more sizes than old lugged frames were. That's why nearly all frame builders gave up on lugs.
I don't know where you get your info, butMXL02
Nov 1, 2002 11:35 AM
many modern steel and carbon frames are lugged, not just the retro ones, case in point, the Colnago Master Xlight. The TIG welded frames are definitely more modern looking and can use over sized tubes, but many many frame manufacturers make lugged frames. In fact, it is often more expensive to get a lugged frame, which makes me believe that one of the reasons TIG has become popular is that it is cheaper. It can probably be done by machine (robotics) as well, making it more amenable to mass production.
Addendum. Not all lugs are steel . . .Look381i
Nov 1, 2002 11:41 AM
I have three lugged road bikes. One was made in 1972 (French frame, Reynolds 531 DB tubes); another, in 1999 (Italian frame, Columbus Neuron tubes). Both are steel tubing with steel lugs. My newest bike has shaped carbon tubes with aluminum lugs (French frame). I decided on it over an Italian carbon bike with carbon lugs. Lance rides a American carbon bike with carbon lugs bolstered by aluminum inserts. Lugs are still alive and well in the carbon world.

I have ridden lugged bikes so long, all my adult life, that a tigged or welded frame seems like it is missing something. I guess that makes me something like a retro-grouch.
I agree . .Dave Hickey
Nov 1, 2002 11:48 AM
My first road bike was an aluminum lugged, aluminum tubed frame. Look at the current trend in high-end Ti. They are using Ti lugs and carbon tubes.
Lugged frames often are an advantage in CFColnagoFE
Nov 1, 2002 1:15 PM
That way they can easily customize tube length without having to make another mold as in the case of a monocoque CFframe. A bike like the C-40 can be made custom pretty easily while a monocoque bike would need a new mold for each size variation--way too expensive for the manufacturer.
Alexx, what is 'Fillet Brazed'...Ride-Fly
Nov 1, 2002 2:08 PM
and where does it fall between the TIG and Lugged methods? My guess is that 'brazed' is more like 'welded'??
Fillet brazing vs. TIG weldingMXL02
Nov 1, 2002 2:22 PM
Fillet brazing vs. TIG welding
Brazing, a lower temperature process than welding, uses a bronze rod to create a fillet--a French word for ribbon--pronounced FILL-it (not fill-LAY). It was previously thought higher welding temperatures would ruin good tubing. We now know because welding is faster, the damaging effect of higher temperature is mitigated by shorter heat duration. While disagreements about the relative merits of lower temperature vs. shorter duration continue, a properly fillet-brazed joint will certainly have greater accident "survivability." I.E., if you run into a tree or parked car, a fillet-brazed joint is less likely to fail. Either joint will withstand decades of normal use.

Because the bronze fillet is softer than the steel tubing it joins, a skilled craftsman can sculpt a brazed joint without cutting into the tube. Please note that the quality of this sculpting (or craftsmanship) is highly variable--look for large smooth fillets with compound radii and long feathered edges. Beware of "overbite." Overbite, a result of hurried or sloppy work, is where part of the steel tube has been carelessly filed away at the edge of the fillet. This creates a stress riser that can lead to frame failure. Unfortunately, overbite is a common flaw found on many fillet-brazed frames.

Unavoidable downside of fillet brazing #1: Price. Because fillet brazed construction requires much more time and skill, the price of a properly fillet-brazed tandem frame will be $300-$500 higher. If the price differential is lower, inspect the joints carefully before taking delivery. Because of the price, most bicycle customers choose a TIG welded frame. Of the seven models of steel tandems we build here at Santana, only the Noventa is still fillet brazed.

Unavoidable downside of fillet brazing #2: Weight. A filleted joint, like a lugged joint, is slightly heavier than a TIG-welded joint (4oz penalty on a single bike, 12oz penalty on a tandem). However, because our fillet-brazed Noventa uses stronger and thinner Columbus NivaCrom tubing, it remains lighter than a TIG-welded cromoly frame. For an even lighter steel frame we could TIG-weld a Noventa, but since weight freaks (as opposed to workmanship freaks) prefer our lighter and less expensive aluminum Sovereign, we don't produce a TIG-welded Noventa.

Because a properly fillet-brazed frame is the ultimate hallmark of a skilled framebuilder, the best reason to buy a fillet-brazed frame is because you value the artistry and can appreciate the builder's skill.
Not MY Paramount!Humma Hah
Nov 1, 2002 2:53 PM
'Mounts of that vintage were lugged, usually with Nervux lugs. To my knowledge, they have NEVER been fillet-brazed.

My Schwinn cruiser has joints which APPEAR to be fillet-brazed, as did the cheaper Schwinn roadbikes such as the Varsity. This was an exclusive Schwinn feature, the use of an "electroformed" head tube. Two forged half-shells were upset-welded to form the head tube with the filleted nipples, then the frame tubes were upset-welded to these. Upset welding is done by jamming the parts together while passing a whopping dose of current thru them. Big flash, and its done.
Humma, is your '75 Paramount 'close coupled?' ...rwbadley
Nov 1, 2002 9:38 PM
It does have the curved seat tube? or not... Our '75 Tandem Paramount has the curved rear seat tube, and is also fillet brazed. It is a real masterpiece. I love to feel the fillets, ohhh so smoooth....ooops I 'm getting carried away...

Fillet brazing is a nearly lost art in the bike frame world. Even more so than lugs. If you find one at a good price, buy it just to save for later, you won't regret it..

Its a '74, short-coupled, chromed lugs ...Humma Hah
Nov 2, 2002 12:15 PM
... and they silver-soldered the lugs. Yes, the "short-coupled" has the curved seat post. I believe the idea was that it made a better climbing bike.

I just thought it was SO neat that the 'Mount's only curved tube is the only tube on the cruiser that's straight, they both came from the same factory, and they're both silver. An obvious set, and I HAD to have that 'Mount, especially when the frame is exactly the size the usual formulae say I should be riding.
You can't chrome-plate a tig-weld.Humma Hah
Nov 1, 2002 2:48 PM
Lugs are just tinkertoys for turning lengths of straight tubing into a bicycle frame. The tubing is joined by slipping the tubes into the lugs and brazing or silver-soldering, two low-temperature techniques that do not affect the strength of the tubing.

Lugs are used by small-scale builders who can't afford the equipment used for mass production, where tig-welding is used to make perfectly good frames.

Lugs are often ornately carved on finer bikes. Some, usually Nervux lugs, are even chrome-plated. This does nothing to actually make the bike better, but it is drop-dead gorgeous eye-candy.
Nov 1, 2002 3:26 PM
Nov 1, 2002 8:43 PM
thanks for all the responses....