lugged vs tig

[shankldu]

tig is lighter lugged looks better in some opinions which one rides smoother /more supple or are they similar . thinking of building up a touring cummuter type rig.

[Mr Cabletwitch]

tig is lighter lugged looks better in some opinions which one rides smoother /more supple or are they similar . thinking of building up a touring cummuter type rig.


I have a lugged serotta and a tig'ed Soma, I prefer the the ride of the serotta, and have generally preferred lugged bikes, but I think its mostly in my head.

[Black Dog]

It is really an aesthetic issue. The strength of the joint will be the same, all else being equal.

[David Kirk]

At the risk of sounding flip - the tubes don't care how they are hooked together. Once they are hooked together they act the same.

dave

[old_fat_and_slow]

It is really an aesthetic issue. The strength of the joint will be the same, all else being equal.

With all due respect, I disagree with this statement.
From a metallurgical standpoint, TIG welding on most steels will leave a significant heat affected zone, which anneals (reduces or removes the strengthening due to heat treatment of the basic tubes from the steel mill) the area around the weld. Hence, the welded and heat affected zone will have degraded strength properties from the basic steel stock. Lugged frames are only heated enought to melt the braze metal into the annulus between the lug and the tube. Brazing temperature is much lower than temperature required to weld most bicycle tubing materials. Hence, the properties around the brazed joint will not be affected as much as the material around a TIG'ed joint.

Yeah, yeah, I've heard all about the new "air-hardened" steels that supposedly aren't affected by welding due to it's initial heat treatment at ambient air temperatures. However, I have not seen enough data in the basic material handbooks (e.g., AMS handbooks, Mil-HDBK-5, MMPDS handbooks) and literature to support these claims, so I am not sure I am drinking that Kool-Aid yet.

Furthermore, according to Doug Fattic (do a search on this forum), lugged frames don't weigh any more than TIG'ed frames.

So if I had my druthers I'd go for the aesthetics of a lugged frame. (Yes, I have a TIG'ed Ti frame, but I have two lugged steel frames also.)

YMMV

[eddief]

due to their super smooth surface, definitely is more aerodynamic...don't ya think :).

[Ahneida Ride]

At the risk of sounding flip - the tubes don't care how they are hooked together. Once they are hooked together they act the same.

dave

Amen

Kelly builds both .... feedback has been uniform.

[Doug Fattic]

tig is lighter...
Actually tig is not lighter even though it may appear to be. A Head tube and the top of the seat tube needs to be reinforced somehow if there isn't a lug there to do that job. The likely solution is a thickened head and seat tube with the result that this combination is most often heavier than plain tubing with lugs.

The real advantage of a tigged frame is that it can be made much faster without the expense of buying lugs so the final product is (or should be) cheaper.

It is possible to make a tigged frame lighter than a lugged frame if special measures are used but that is not likely to be done because that will increase the risk of failure. The whole point of making a tigged frame is to reduce cost.

[old_fat_and_slow]

At the risk of sounding flip - the tubes don't care how they are hooked together. Once they are hooked together they act the same.

dave

Although the tubes don't care, the strength properties are affected by welding.

STIFFNESS (hence, riding characteristics) is not affected, but STRENGTH can, and usually is affected.

[dave thompson]

With all due respect, I disagree with this statement.
From a metallurgical standpoint, .....<snipped>
YMMV
Although the tubes don't care, the strength properties are affected by welding.

STIFFNESS (hence, riding characteristics) is not affected, but STRENGTH can, and usually is affected.

Old, while you may be technically correct, for all intents and purposes, IMO "our" use of tig'd/lugged bicycle joints, the strength of the joints will be the same. Assuming of course well made joints of both stripes.

[Fixed]

bike lug and tube joined = sexy
tube to tube = not so much
imho
cheers

[tannhauser]

Not sure if this is a troll topic...

If you're building a tourer/commuter, it doesn't matter how it rides unladen.
It'll change once you pile crap on it.

[jr59]

bike lug and tube joined = sexy
tube to tube = not so much
imho
cheers

What about fillet (spelling)

It's joint to joint and very sexy! :banana:

[David Kirk]

Although the tubes don't care, the strength properties are affected by welding.

STIFFNESS (hence, riding characteristics) is not affected, but STRENGTH can, and usually is affected.

Right you are. The way we hook tubes together has a large effect on how well they stay together or how well the tubes themselves last but the original question wasn't about strength or durability but one of ride quality. There should be no difference in ride quality regardless of how the tubes are hooked together.

From the testing I've done the way to get the strongest and longest lasting steel bike is to fillet it together. But to be frank - if you have a competent builder do whatever joining method (tig - lug - fillet) it will last more than a lifetime. If the builder isn't skilled or experienced or if they chose the wrong tubes given the size/weight of the rider then all bets are off.

dave

[sg8357]

If you're building a tourer/commuter, it doesn't matter how it rides unladen.
It'll change once you pile crap on it.

Depends on the bike, I had one that was much worse loaded, one that
was slightly worse loaded, one that was much the same loaded or not.

On the original topic, the order of aesthetic merit is
Bi-Lam
lugged
filet
electro forged
tig
FSW
nano assembler knitted.
cast magnesium
plastic

[old_fat_and_slow]

Old, while you may be technically correct, for all intents and purposes, IMO "our" use of tig'd/lugged bicycle joints, the strength of the joints will be the same. Assuming of course well made joints of both stripes.

First, let me say I am in no way condemning TIG welding as a valid fabrication technique for bicycle frames. However, it does have inherent challenges and side effects (annealing of adjacent material) to the process.

Although by and large, most TIG'ed frames will outlast their owners,... some bad ones get through.

And when I see failures such as these two:

http://i461.photobucket.com/albums/qq332/catchernrye/bikes/Ritchey_ti2.jpg

http://i461.photobucket.com/albums/qq332/catchernrye/bikes/MTB_frame2.jpg

that is, failure initiating adjacent to a weld, given my druthers, I'd go with lugged fabrication.


I don't claim to have an encyclopedic knowledge of all metallic bicycle frame failures. However, I can't recall ever seeing a lugged frame failing at a lug joint. I'm sure it has happened, but I'd be willing to bet, it is a lot more rare than a failure at a TIG'ed joint.

YMMV, dissenting opinions are perfectly welcome. :)

[tannhauser]

Depends on the bike, I had one that was much worse loaded, one that
was slightly worse loaded, one that was much the same loaded or not.


Yeah, the point is how are you going to build consistent ride quality loaded vs. unloaded? Maybe Bruce Gordon knows.

[shankldu]

well from weighing bikes of similar size and same tubing tigs are lighter , but i like the look of lugs. I have seen welds crack before and never lugs separate from a tube . With my 220lbs and 40 lbs of gear i would think lugged would be the way to go.

[rugbysecondrow]

well from weighing bikes of similar size and same tubing tigs are lighter , but i like the look of lugs. I have seen welds crack before and never lugs separate from a tube . With my 220lbs and 40 lbs of gear i would think lugged would be the way to go.

I don't think absolutes are appropriate. Bruce Gordan sells the Rock n Roll touring frame which is TIG.

I think any bike built for the proper use should function as intended, regardless of joining style.

[bigflax925]

I can't tell the difference in ride between lugged, TIG'd or fillet. I prefer the look of lugs or fillets, but it's not a deal breaker for me if it's a bike I want to try.

[oldpotatoe]

tig is lighter lugged looks better in some opinions which one rides smoother /more supple or are they similar . thinking of building up a touring cummuter type rig.

Whether tig welded or brazed with lugs, neither alone has any influence on how the bike rides. Way too many other things involved, not the least of which is subjective assessment of how a frame rides. Having said that, my steel frames will always be lugged cuz it looks better, IMHO.

Ciocc
Waterford
Merckx Corsa
Merckx MXLeader
DeRosa Giro de Italia

[CNY rider]

Depends on the bike, I had one that was much worse loaded, one that
was slightly worse loaded, one that was much the same loaded or not.

On the original topic, the order of aesthetic merit is
Bi-Lam
lugged
filet
electro forged
tig
FSW
nano assembler knitted.
cast magnesium
plastic

Can we also agree that "looks like plastic that melted" would go on the bottom of the list? ;)

[Terry312]

Can we also agree that "looks like plastic that melted" would go on the bottom of the list? ;)

First of all let me say I prefer traditional steel lugged frames. To me they look right. As far as I know there is no reason to tig weld steel, other than to save money and satisfy the customer's notion that it is better, or weighs less.

Eliminating lugs eliminates the cost of the lugs, finishing, and the cost to have an inventory of lugs. One exception is that without lugs the builder is no longer burdened with geometry restraints. In that case that is where fillet brazing is a better alternative. Tig welding utilizes such high temperatures, it's hard for me to believe the adjacent steel is not compromised.

Tig welding, ATMO, should be used where brazing doesn't work, period. The general public has been bamboozled into thinking it's better, lighter... The big builders won't argue because the tube manufacturers say their steel can handle it. Maybe it can, when an expert tig welder is at the helm.

Just my two cents. And I agree with some other above that it is only one part of the mix concerning ride, feel...

[beer_meister]

First of all let me say I prefer traditional steel lugged frames. To me they look right. As far as I know there is no reason to tig weld steel, other than to save money and satisfy the customer's notion that it is better, or weighs less.

Eliminating lugs eliminates the cost of the lugs, finishing, and the cost to have an inventory of lugs. One exception is that without lugs the builder is no longer burdened with geometry restraints. In that case that is where fillet brazing is a better alternative. Tig welding utilizes such high temperatures, it's hard for me to believe the adjacent steel is not compromised.

Tig welding, ATMO, should be used where brazing doesn't work, period. The general public has been bamboozled into thinking it's better, lighter... The big builders won't argue because the tube manufacturers say their steel can handle it. Maybe it can, when an expert tig welder is at the helm.

Just my two cents. And I agree with some other above that it is only one part of the mix concerning ride, feel...


Here ! Here !!! very eloquently stated! I couldn't agree more. :beer:

[Scriv]

With all due respect, I disagree with this statement.
From a metallurgical standpoint, TIG welding on most steels will leave a significant heat affected zone, which anneals (reduces or removes the strengthening due to heat treatment of the basic tubes from the steel mill) the area around the weld. Hence, the welded and heat affected zone will have degraded strength properties from the basic steel stock. Lugged frames are only heated enought to melt the braze metal into the annulus between the lug and the tube. Brazing temperature is much lower than temperature required to weld most bicycle tubing materials. Hence, the properties around the brazed joint will not be affected as much as the material around a TIG'ed joint.

Yeah, yeah, I've heard all about the new "air-hardened" steels that supposedly aren't affected by welding due to it's initial heat treatment at ambient air temperatures. However, I have not seen enough data in the basic material handbooks (e.g., AMS handbooks, Mil-HDBK-5, MMPDS handbooks) and literature to support these claims, so I am not sure I am drinking that Kool-Aid yet.

Furthermore, according to Doug Fattic (do a search on this forum), lugged frames don't weigh any more than TIG'ed frames.

So if I had my druthers I'd go for the aesthetics of a lugged frame. (Yes, I have a TIG'ed Ti frame, but I have two lugged steel frames also.)

YMMV

With all due respect you gave in your disagreement, I'd like to say that I agree with you to a point, but having experience with many forms of welding, including brazing, I'm inclined to think that the area to be joined will be exposed to enough heat to make the steel red hot in order for the brass to flow. If it is not heated enough, no joint is formed. On the other hand when tig welded the parent metal is heated extremely quickly in a small area and then cools. A torch used for brazing is simply not capable of this precision. In short, I'll buy the argument that one is as good as the other, but I'm not sure about one is better than the other. I also think that the area around the weld would cool much quicker than the lugged area. Whether or not this is good or bad depends on the alloy used, and rate of cooling.

Interesting thread. On one hand I appreciate the classic look of a lugged frame. It is to be cherished. Having put beans on the table for some years with a welding hood on, I do appreciate a person that knows his craft. d

One thing I should add, As I recall (and it has been some years) the melting point of steel is 2150 degrees F. I couldn't guess about brass, but I magine over 1800 F. One thing I do recall is that you had to be careful working with brass or the parent metal would go molten on you and cause all kinds of issues. Point being that I don't think that the temps are as far apart as one would think. Hope this helps. d

[mudhead]

Tig if you're going to ride it... lug if you're going to look at it

[parris]

It seems that the various methods to attach tubes together relies on the skill of the person doing the work. All styles are valid and especially with today's steel alloy's make for what I believe are the best frames we've ever seen. If the person at the bench doesn't have the chops to turn a collection of tubes into something great the joining method is probably down on the list of issues that particular frame will have.

In the end a properly built steel frame will outlast every single one of us on the forum several times over. One question about the photos of the broken frame shown earlier. Was that a steel frame or something else? I've seen aluminum parts break like that but I haven't seen steel come apart like that.

[Terry312]

The first one looked like titanium to me, maybe stainless, the other?

But the first one's welds looked like crap to me, either a bad torch or some friggin machine welds.

[the night owl]

that's the way a bicycle is meant to be made.

[Terry312]

I thought I read in one of the cycling publications that Serotta might build a 40th Anny bike, steel and lugged. It is going to be real expensive, ~10K+

Going out on a limb, if true, I'll be interested in review/comparison with the current steel frames available from Serotta. It'd be funny if it were preferred over some of his current offerings. That said it's priced beyond my range. I think Serotta and others don't want to go back, but like to show it can be done. Making a Sachs... Look like a deal. Hell, Serotta doesn't really want to fix, paint... bikes like mine anymore. I just hope they don't dump the machines to shape the tubes.

[Fivethumbs]

You know how we've all read about how the pro riders / managers and the European bike industry / frame builders have all kind of been entrenched in tradition. This makes me wonder why Dario started Tigging frames in the early 90's (late 80's?) when lugged had been the standard build method for so many years. Since he was building frames to be raced in the biggest races by the biggest stars, I can't imagine that cost would have been a factor. Plus, the frames were all standard geometry (i.e. level top tubes), so that leaves out specialized geometry as the reason. What's left? Weight? Faster construction? Anybody got any ideas?

[Terry312]

To be part of 'the latest and greatest' or, market pressure.

[picstloup]

can you change out a top or down tube on a tig'd frame after a crash or some mishap as easily as a lugged frame?

personal preference, i've always loved small, cleanly designed lugs...like on my old derosa primato...or even on the tommaso which i still have...after that filet brazing with smooth joints...tig, no matter how even, regular, just never floats my boat...

[slowgoing]

OFAS –

I’m not sure the pic of the mountain bike tubing failure supports the proposition that TIG welding weakens the adjacent material. The pictured tubing appears to have failed because a suspension shock that induces sizeable cyclic loading and unloading is mounted on the OD of the tube by those welds. The welds are therefore the point at which those cyclic loads are applied to the OD of the tube, so that is where you would expect any failure to occur. Would the result would be different if the shock was mounted by lugs or by brazing? I’m not so sure. I mean, if you mount a shock to the OD of a hollow tube, where else would you expect the tube to fail other than at the mount where all of the cyclic loading and unloading is occuring?

There are also other possible explanations for the failure occuring at the welds. It could be that the OD and thickness of the tubing were insufficient to support the shock loads no matter what attachment method was used. Moreover, the brake bottle hole across the diameter from the shock mount obviously created a stress riser promoting failure at that particular location. Would the tubing have failed, and in that area, if the hole was located a bit upstream?

[soulspinner]

Glad we have all types. If I had mo money, I d have a tig(xcr,953), a lugged, and a fillet bike.

[saab2000]

If welded frames sucked I don't think Serotta would make so many of them.

[Scriv]

The first one looked like titanium to me, maybe stainless, the other?

But the first one's welds looked like crap to me, either a bad torch or some friggin machine welds.

I believe the other to be aluminum. I'd like to see the whole picture as I believe the failure began at the water bottle boss-just a guess. Which brings up another point, were the owners "just riding along" when it happened, or hucking off the top of a house. Every material and process has it's limits.

[Mark McM]

can you change out a top or down tube on a tig'd frame after a crash or some mishap as easily as a lugged frame?

Yes. Maybe even more easily, given the general consensus that tig is faster and cheaper than lugs. Cut the tube out, grind down the old weld, and weld in the new tube. I know of many tig'ed frames that have had tubes replaced.

Here's an extreme example: The earliest Merlin frames (tig welded titanium) used pressed-in BB bearings. Later, they developed a method to produce threaded BB shells. Merlin then offered a service to replace the BB shell on earlier frames with the new threaded shells, which obviously required re-welding the joints with the down tube, the seat tube, and both chainstays. The service was offered at a quite reasonable price with a fast turn-around. I know a couple of people who had this done, and you couldn't tell from looking at them that it had been done. I haven't heard of any frame that cracked around the replaced bottom bracket shells.

Oddly enough, I had a tube replaced on a frame which used a combination of joinery - the tube was lugged on one end, and tig'ed on the other. After the tube was replaced, it looked just like new, and served many years before the frame was retired.

[beer_meister]

... snippage ...
One thing I should add, As I recall (and it has been some years) the melting point of steel is 2150 degrees F. I couldn't guess about brass, but I magine over 1800 F. One thing I do recall is that you had to be careful working with brass or the parent metal would go molten on you and cause all kinds of issues. Point being that I don't think that the temps are as far apart as one would think. Hope this helps. d

Per this website (http://www.muggyweld.com/melting.html) there is almost 1000 degrees F, between the melting points of brass and several grades of steel. So I believe that OF&S's assertion that brazing does not "eff up" the heat treatment in the heat affected zone, nearly as significantly as Tig welding does, is valid.

I agree with your point that a Tig'ed weld may cool faster, but that's not always desirable when heat treating steels. Sometimes during heat treating you have to hold the raw stock at an elevated temperature for many hours, so the fact that a Tig'ed weld cools faster, is not necessarily a good thing. It depends on the material, and how it was heat treated.

[beer_meister]

OFAS –

I’m not sure the pic of the mountain bike tubing failure supports the proposition that TIG welding weakens the adjacent material. The pictured tubing appears to have failed because a suspension shock that induces sizeable cyclic loading and unloading is mounted on the OD of the tube by those welds. The welds are therefore the point at which those cyclic loads are applied to the OD of the tube, so that is where you would expect any failure to occur. Would the result would be different if the shock was mounted by lugs or by brazing? I’m not so sure. I mean, if you mount a shock to the OD of a hollow tube, where else would you expect the tube to fail other than at the mount where all of the cyclic loading and unloading is occuring?

There are also other possible explanations for the failure occuring at the welds. It could be that the OD and thickness of the tubing were insufficient to support the shock loads no matter what attachment method was used. Moreover, the brake bottle hole across the diameter from the shock mount obviously created a stress riser promoting failure at that particular location. Would the tubing have failed, and in that area, if the hole was located a bit upstream?


Sure, without doing some SEM of the failure surface it is difficult to tell exactly what caused that failure. You are certainly correct in your thesis regarding cyclical loading leading to fatigue failures. Sure the failure may not have been the result solely of lower strength properties in the HAZ. It could have been due to inclusions in the weld, excessive porosity, ... who knows. Since most bike manufacturers don't do any NDT on their welds, who knows what kind of crap could have been in that weld. However, fatigue failures are a function of the material's fatigue strength, and guess what, having a significantly annealed area adjacent to a primary load path spells trouble. Annealing not only affects static strength, it affects fatigue strength as well. So sure, the photo of the broken mountain bike frame doesn't prove that the failure was a result of the Tig weld. But, since the fracture surface is running parallel to the weld, I would bet that the fracture toughness of the HAZ was reduced as well. Furthermore, I would be willing to bet that if that joint was somehow a lugged connection, it probably would have survived.

Did I prove anything. No, but I would have to say I agree with OF&S regarding lugged probably being a stronger joint.

[Mark McM]

Per this website (http://www.muggyweld.com/melting.html) there is almost 1000 degrees F, between the melting points of brass and several grades of steel. So I believe that OF&S's assertion that brazing does not "eff up" the heat treatment in the heat affected zone, nearly as significantly as Tig welding does, is valid.

Regarding whether brazing causes annealing of the steel tube is not a question of the difference in melting temperatures - the annealing temperature of steel (750-900 deg. C, depending on composition) is below the melting temperature of brass (900 - 950 deg. C), so there will be at least some annealling of the steel. (Some steels, such as the old Reynolds 753, could only be silver brazed, which requires lower temperature.) But of course,there are many factors affecting the loss of strength of the tube due to the heat of joining (temperature, time, heat penetration, rate of cooling, alloy composition, etc.), so just knowing the melting and annealing temperatures doesn't show the whole picture.

[beer_meister]

Regarding whether brazing causes annealing of the steel tube is not a question of the difference in melting temperatures - the annealing temperature of steel (750-900 deg. C, depending on composition) is below the melting temperature of brass (900 - 950 deg. C), so there will be at least some annealling of the steel. (Some steels, such as the old Reynolds 753, could only be silver brazed, which requires lower temperature.) But of course,there are many factors affecting the loss of strength of the tube due to the heat of joining (temperature, time, heat penetration, rate of cooling, alloy composition, etc.), so just knowing the melting and annealing temperatures doesn't show the whole picture.

Yup, I concur.

[Scriv]

Per this website (http://www.muggyweld.com/melting.html) there is almost 1000 degrees F, between the melting points of brass and several grades of steel. So I believe that OF&S's assertion that brazing does not "eff up" the heat treatment in the heat affected zone, nearly as significantly as Tig welding does, is valid.

I agree with your point that a Tig'ed weld may cool faster, but that's not always desirable when heat treating steels. Sometimes during heat treating you have to hold the raw stock at an elevated temperature for many hours, so the fact that a Tig'ed weld cools faster, is not necessarily a good thing. It depends on the material, and how it was heat treated.

I appreciate the correction and reference to the website. The steel being 26-2700 and brass being 16-1700. As far as the cooling rates and whether or not it is desirable? I said that, but you "snipped it".

I also appreciate the information on heat treating, having worked in the industry I agree with your assessment.

My main point I was attempting to make, (and I admit I did a poor job of it) was that with a oxy-acetylene torch you lack the precision to heat only the area required and end up overheating things possibly as much as Tig welding it in the first place thereby negating the benefit of brazing. Is this an undisputed fact? I'd say no, just a unsubstantiated feeling I have based on experience admittedly from some time ago.

As I said before, interesting thread, fun to think about. :beer:

[Scriv]

Regarding whether brazing causes annealing of the steel tube is not a question of the difference in melting temperatures - the annealing temperature of steel (750-900 deg. C, depending on composition) is below the melting temperature of brass (900 - 950 deg. C), so there will be at least some annealling of the steel. (Some steels, such as the old Reynolds 753, could only be silver brazed, which requires lower temperature.) But of course,there are many factors affecting the loss of strength of the tube due to the heat of joining (temperature, time, heat penetration, rate of cooling, alloy composition, etc.), so just knowing the melting and annealing temperatures doesn't show the whole picture.

I wholeheartedly agree with that statement. I also think that without scientific analysis of tested proceedures we can hang around here, cuss and discuss all we want without finding an answer. Still, it's fun to think about.

[Peter B]

My lugged frames exhibit exemplary lateral stiffness, my fillet brazed frames are vertically compliant and my tigged frames corner like they're on rails.

Feel free to interchange each joining method with any handling characteristic.

Can we go riding now?

[Scriv]

My lugged frames exhibit exemplary lateral stiffness, my fillet brazed frames are vertically compliant and my tigged frames corner like they're on rails.

Feel free to interchange each joining method with any handling characteristic.

Can we go riding now?

Amen. Let's go.

[tannhauser]

My lugged frames exhibit exemplary lateral stiffness, my fillet brazed frames are vertically compliant and my tigged frames corner like they're on rails.

Feel free to interchange each joining method with any handling characteristic.

Can we go riding now?

What about beans, a big hill of them?

[Peter B]

What about beans, a big hill of them?


Oh Boy! Hills!! I like hills!!!

[parris]

Wait... you mean we're actually supposed to ride these things?

[jaykosta]

In a properly done lugged brazed joint, approximately how much of the joint strength is tube-to-tube, and how much is tube-to-lug-to-tube ?

I like the appearance of lugged frames, but it is not easy to tell whether the filler metal has fully entered the joints.

Jay Kosta
Endwell NY USA

[beer_meister]

In a properly done lugged brazed joint, approximately how much of the joint strength is tube-to-tube, and how much is tube-to-lug-to-tube ?

I like the appearance of lugged frames, but it is not easy to tell whether the filler metal has fully entered the joints.

Jay Kosta
Endwell NY USA

In a properly mitered joint, the braze should react only tensile loads on the joint. The lug should react all shear and bending loads. If the joint is mitered correctly, compression loads should be transferred directly from one tube to the other.

Thats my story... and I'm stickin' to it. (At least for now.)