danarello

What is the difference between the early 90s Centurion TG Expert diamondback steel frame and say the late 80's Centurion/Schwinn/Miyata lugged steel frames? Are non-lugged steel frames an improvement. What is your humble opinion?

Classtime 

Tig welded frames are lighter and less expensive to manufacture. Win win for some. Indurain won a tour or two on a tigged frame and Dario Pegoretti sold more tigged frames than lugged so there is that.

Chombi1 

TIG welding had been around since the 40's in the aircraft industry.
I guess the trickle down into the bike industry was a bit delayed as I suspect the bike companies was a bit resistant to technological advancements that could have meant higher costs. But when equipment for TIG welding was more available commercially, the industry jumped on it.....and said heck with beautiful lugs and traditional frame aesthetics.....sad....
We all saw it coming when the welded Unicrown forks reared its ugly head in th late 80's.......
I would think though that a welded frame could be ultimately much stronger that one that is brazed together.

Lazyass

I think the biggest difference is when the unicrown fork trend started. They ride stiffer and the ones I've had are heavier on average. Although when they first came out I thought they looked cool and modern.

T-Mar

The big advantage of TIG welding was that it freed the designer from the constraint of standardized lugs and the high cost of developing custom lugs for a non-traditional design. You could non-choose standard angles, non-standard tube diameters and non-standard tube shapes without heavy investment in new tooling for lugs. Of course,this had always been a possibility with fillet brazed frames but TIG welding opened the doors for mass production frames. It could also have been achieved with Peugeot's and Motobecane's internal brazing process but they didn't see the possibility until TIG opened their eyes.

BMX and ATB designers had been using TIG construction for a number of years prior to it being adopted for mass production road bicycles. It allowed for the sloping top tube ATB trend in the late 1980s, the use of larger diameter tubes in thinner gauges to increase stiffness without weight penalty and the ovalized tube ends, to selectively increase stiffness.

Diamondback's TG road series was a relatively conservative introduction to the advantage of TIG welding. Angles and tubes shapes were traditional but the diameter was oversize and TIG welding allowed shorter butt lengths. The freedom of lugs would eventually lead to the sloping tube, compact, road frame design. Personally, I consider TIG construction a step forward in all aspects, though aesthetics is arguable. It brought the designers one step closer to realizing their ideal designs by providing additional design parameters they could tailor. Some members may not be in agreement with these design changes but they did lead to lighter, stiffer and/or more comfortable frames, depending on the designer's intent. That's progress.

CliffordK

Non-lugged frames have been around for quite some time. Just look at the old Schwinns.

Ignoring the spot welded frames by other brands of the era, Schwinn made solid frames, using either electro-forging, or filet brazing.

https://www.sheldonbrown.com/varsity.html
https://www.sheldonbrown.com/schwinn-braze.html

Back in the 70's and early 80's, I remember discussions that lugged frames were stronger than other joining methods.

I wonder if, however, there were many radical changes in the bikes from the 50's to the early 80's, and structural quality of one frame or another really depended on rapidly evolving changes.

In particular, metal alloys were improving, as well as processing.

So, in the 50's, if one wished to make a lighter frame, one might choose thinner tubes, but then the joints became stress points... thus the benefit of the lugs.

Then came the double butted tubes, and thus strength derived from tubing profiles.

However, the Renolds 531 was not particularly tolerant to welding, and thus the benefits of brazing.

It may be that a good filet brazed frame would have been just as good as a lugged frame, but at that time, the cheaper electro-forged and even spot welded frames were hitting the market.

So, a good well made lugged frame would just stand out from the crowd of non-lugged frames.

I'm a bit surprised that companies like Peugeot adopted the TIG frames when they did, but changes in the materials allowed the tig frames, and the big companies were all about mass production, not custom boutique frames.

exmechanic89

Personally I think TIG welded frames look better than lugged frames. And I think of them as a step forward as well.

52telecaster

I prefer the look of lugs but for years I assembled bikes at Kmart. These were mostly huffy and Murray's. The bikes were awful but one thing was clear. With horrible looking welds, the frames never failed at the joints. I saw plenty with bent forks and bent or buckled downtubes but never a broken weld. If welding were an inferior process I think we would have seen it in broken welds.

Fivethumbs

Some of the Diamond Backs were OS tube sets, so there's that.

mitchmellow62

Is it true that the advent of "air hardened" alloys made tig welding more advantageous? My understanding is that with air hardened alloys the metal is actually stronger after welding. That alloys for thinner tubes at the joint and lighter frames.

abellanti

I think TIG welded frames gained acceptance during the mountain bike boom. Everyone in the eighties wanted a high end lugged Italian race bike. I would of scoffed at a welded frame in the eighties, but once I realized high end mountain bike builders were welding frames, then it became acceptable. I still think welded frames..outside of titanium frames...look utilitarian and ugly on road frames. Now as far as performance gains, one can argue tig welded frames have an advantage.

RobbieTunes

himespau 

Lugs provide the chance to be more elaborate, and I like fancy looking things with painted windows. I'm sure tig welds (when done properly) are plenty strong (maybe stronger than a braze), but I've mainly seen TIG welds on low end bikes where speed is the main construction concern and they look like garbage (and I've made plenty of garbage welds in my time, so I know garbage welds). I'm sure a bike TIGed together by someone who took the time to make nice, clean welds (or ground them smooth after the fact) would look nice. It'd still miss that something extra that the details of lugs provide, but it'd be aesthetically fine.

Hudson308 

For a direct comparison, try riding a lugged Trek 750 Mulitrack vs. the later TiG welded version.
The TiG frame is a wobbly noodle, to the point where I can't imagine trying loaded touring on it.
The lugged version has just the right amount of give vs. stiffness to inspire confidence with comfort.

bikemig 

Or it could be that these bikes were carefully designed so that everything else failed long before the frame would . . .

Just saying.

mgopack42 

I saw plenty of department store bike break at the welded joints, especially the seat tube to BB joint.

mgopack42 

I was told, when I worked for a frame builder, that the reason the good frames were lugged and silver soldered was that the alloys used (CrMO, etc) would lose their strength / characteristics if heated above a certain temperature (I wanna say 1700?, a dull red orange glow) silver solder melted at a lower temperature ( again, I wanna say 1400?), so as long as you judiciously applied heat to the lug when soldering, you could avoid overheating the tubes, and maintain the structural integrity of the frame you were building.
That being said, I had a Viscount Aerospace Pro (fillet brazed I think) and I was forced to defend the quality of the frame endlessly with one friend, since it had no lugs, and was obviously no better than a Varsity!

Chombi1 

Uhmmm,...most like because...they were "Department Store" grade bikes......

52telecaster

I never once saw that. Any time someone brought one back in, a failed frame would require a warranty claim. I wrote a few on bent downtubes but they were always refused. In 4 years of building 100+ bikes a week I can't recall ever seeing a broken weld returned to the store for warranty. I am also sure I havnt seen everything, just saying it must be an uncommon failure, along the lines of a failed braze.

mgopack42 

I can say that i had 2 frames replaced under Warranty in my life. First was a Schwinn Varsity that had the kickstand weld on tube broken off. they were not meant to support the bike and the pudgy rider. the second was a Reynolds 531, Ted Williams Free Spirit. I ran that one into the back of a parked car while I was doing my paper route. I still remember how easy it bent! good

thinktubes 

I've had both a late 80's lugged Centurion LeMan's and an early 90's Diamondback Interval TG.

Hard to compare since the Diamondback had Tange OS tubing and had a stiffer (but not harsh) ride.

The geometry seemed a bit more laid back on the DB - it really liked to go in a straight line. The Centurion was a little more zippy and fun.

Dfrost 

mstateglfr 

wat?

Ive ridden both frames- a dark blue lugged frame thats from probably '92 or so, and one from a couple years later that was welded...maybe '94?
Anyways- they were the same geometry and both actually matched the geometry of Trek's 520 touring bike back then. They both felt like what they are...steel frame hybrids.

Cant say I have ever heard a claim that welded frames are noodly due to being welded.

TenGrainBread 

It wouldn't be a proper forum thread without some crackpot claims like that

TenGrainBread 

I think the aesthetic preference for lugs is interesting because it is a preference for a "hidden" fabrication. The joint is hidden from view, as is the braze. It looks "clean" because you see no evidence of the joining process. The lugs are geometric unlike a TIG weld bead or bare fillet.

I understand this but it seems silly to me because the frame's quality is mostly about the skill of the framebuilder in joining the tubes, not how good they are at filing and sanding away the evidence. I think a well-laid TIG bead is far preferable aesthetically to a lug because it bares the welder's work for all to see.

TIG welding is cleaner, faster, and takes more practice than lug or fillet brazing. This is why TIG welding is the preferred joining method in the high-end fabrication industries, whereas brazing is all but non-existent. It remains in custom bikes because consumers have an aesthetic preference that trumps functionality, and because many custom framebuilders don't have formal training in fabrication and welding so prefer to use an easier construction method that requires more cleanup time.

Having said that, an interest in vintage road bikes necessitates lugs. I'm not against them on my vintage bikes and like the look.