T-Mar, wow!

Have you ever considered writing a book on bicycle technical history, at least that to which you've had inside exposure? You seem to have the subject pretty well covered, going by your extremely knowledgable and detailed contributions to threads like this. :beer:

Thxs for the compliment. The subject has been raised before. I've considered it and have a few projects which I'm considering but will probably not come to fruitioin. So far, I've been content supplying technical and historical information for other people's books and websites (both credit and uncredited) and, of course, posting here.

Yes, I tried to edit out that sentence, right after I posted it, but you were too fast! :o

Good observation that cromo frames started appearing in just-above-bottom-level bikes in the 80's. However, they were about as heavy as bottom rank bikes, so the advantage seems questionable. Take something with the same strength-to-weight ratio as cheap stuff, and use the same amount of it. What's the result? I think it's something that's stronger than a cheap frame, but in general, the cheap frame was strong enough. So I think most of what it gives you is bragging rights.

T-Mar, please write a book! It's great to read this stuff.

This is what happens when one presumes too much. First, I have always been intrigued with my 1985 Peugeot PH 501. From the Peugeot catalog.

Until now lugless racing bicycles made with high quality lightweight tubing were produced on by a few very talented craftsman and priced way beyond the budget of most riders. Once again Peugeot has been the innovator making the first lugless bicycle using Reynolds 501 chromoly tubing. The result is out lightweight and affordable PH 501.

While I am highly skeptical of catalog hype, the bike was relatively light (23 lbs with pedals) and lugless. Since 501 was Reynolds butted version of their 500 CrMo it made sense that a lugless butted frame could be made as well as a lugged frame, as the lugs work as external butting. The mistaken post was meant to say the prior to 501, "Reynolds" CrMo frames were plain gauge or "straight pipe", instead I made the blanket statement that all bike frames prior to 501 were straight pipe, which was obviously wrong; but you quoted me before I could edit that out; you are very fast!

Anyway my post should have been Peugeot specific, but it certainly resulted in a plethora of information from T-Mar; not the result I was hoping for, but it turned out not to be a total loss. :rolleyes:

Maybe we should have a sticky with T-Mar's collected posts.

Junkers also built corrugated metal aircraft with metal frames in the First War (as early as 1915), but I doubt they were Cro Mo or anything like that. I think they were "electrical" steel or the like at first, then switched to duralum.

Tom, I'm going to have to respectfully disagree. Many tubing manufacturers offered seamed, butted, CrMo tubesets that used the same wall thickness and butt lengths as their seamless tubesets, resulting in comparable weights. The introductions of these seamed tubesets, in conjunction with component technology trickle down, allowed bicycle manufacturers to offer sub $300 bicycles in the mid-1980s that weighed around 25 lbs.

That's about a 3lb weight reduction with only a doubling of price over what was being offered a decade earlier. While some of it can be attributed to the components, notably the widespread adoption of aluminum rims and aluminum cotterless cranks, the deduction in frame weight is not inconsequenttial. Entry level frames with seamed, butted CrMo main tubes and hi-tensile stays were running around 5 lbs in a 23" size.

Making the post Peugeot specific would not have precluded any issue, as the Peugeot PH501 was not TIG welded as you suggest. These frames were internally brazed using doughnuts of brazing material that were inserted into the ends of the mitred tubes. When heated using a ring torch, the brazing material material reflowed and some was sucked through to the outside of the tube by capillary action. The resulting joint had a large fillet on the inside with a smaller fillet on the outside. One of the major benefits of this method was that it allowed for visual inspection of joint quality. The presence of the fillet on the outside indicated the quality of the reflow via the size of the fillet and the amount and size of voids.

Here's an illustration from an early eighties Peugeot catalog showing the type of lugless "internally brazed" joint T-Mar refers to.

http://i32.photobucket.com/albums/d7...psf9fb253c.jpg http://i32.photobucket.com/albums/d7...ps04ab5136.jpg

Of course, Peugeot managed to ignore the mass produced and affordable Lambert/Viscount lugless chrome-moly frames that were on the market a full decade before the PH 501...

The protoype Junkers all-metal aircraft reportedly used frames constructed from steel angle channel and I-beams. While I've seen nothing on the alloy designation, I suspect it was similar to what Fokker was using. The production model that served in the Great War used primarily aluminum tubing for the frame and a corrugated aluminum skin, though they did use a 5mm "chrome-nickel" steel sheet on the forward fusealge for engine and crew protection. I've seen the sole surving sample which resides in the National Aviation Museum in Ottawa.

You know as wrong as I was about all this, I never would have known the real story without posting. While I don't necessarily want to air my ignorance in this area, I certainly learned a lot. I don't plan on making a habit of this, but the "internally brazed" joint was something I actually saw in "How It's Made" one time, I just didn't know it was what Peugeot used also.

As apoint of interest, that How It's Made segment was actually filmed at a Peugeot manufacturing facility. It's the Procycle factory in Saint-Georges Quebec. Procycle had been manufacturing internally brazed Peugeot for the Canadian market since 1988, then took over the internally brazed manufacturing for the USA market in 1990. By then the process had been named DBS (Direct Brazing System). The video was made just about the time that Procycle's Peugeot license would have expired, circa 2000/2001. Consequently, the video features CCM bicycles, a brand that Procycle bought in 1983. Regardless, those are the actual manufacturing processes that would have been used to build many of the North American Peugeot.

You are a bike frame knowledge god!

I love that show!
and have learned so much about how hockey sticks, skates, gloves and snow-blowers are made...Oh, Canada! ;)

really, I do love that show!

I am relieved this thread has not dug up the tired and misleading old debate between Columbus/CrMo and Reynolds 531/MnMo fans. (Of course my 531-tubed Capo is "soft" and my Columbus tre tubi Bianchi is "stiff," but look at the difference in frame geometry, reflecting a 20-year evolution in European road surfaces and road bicycle frame design philosophy.)

American Eagle bikes were built by Kawamura circa 1970, with the top-of-the-line Semi-Pro and Road Compe models using an Ishiwata double-butted CrMo with extremely disappointing ride quality (heavy and soft -- been there, done that, even had a Nishiki t-shirt). Japanese tubing quality improved markedly during the 1970s, such that the higher-end Nishikis were world class by the end of the decade.

Okay, so, I read the comments related to my additional questions connected to the original posters questions. I agree with T-Mar's remarks to Tom's comments. 4130 Chromoly (aka bike tube chromoly) is 1.75 times stronger than 1020 high tensile (aka bike tube hi-ten). So, in theory, a frame made from chromoly could end up being 60% lighter. Chances are though, the difference is less. For one, standardized tube diameters and standardized tube wall thicknesses mean that you probably couldn't get EXACTLY the tubing dimensions that would be ideal. For instance, your calculations may say that the perfect seat tube (with a chosen wall thickness of .08") would have a diameter of .83467 inches. Well, .83467 isn't standard, so you would probably be forced to round up to the nearest standard diameter, say .875". Also, a lot of frames used chromoly tubing for the main tubes (which have approximately 1" diameter) but hi-ten stays (where, because of the comparatively smaller cross-sectional area of the tube, the weight savings would be more diminished, and the cost not worth the weight savings). I would like to know a comparative weight of a 23" size frame made with hi-ten tubing, anyone know? Plus, I have a KHS Classic bike, made with Tange #5 tubing (which I believe to be seamless) that has components with a 1981 manufacturing date. I assume that it was fairly "entry level" for it's era, with it's components being fairly closely matched to my 1977 Schwinn LeTour II (definitely near entry level specimen for it's day). So, I question whether the ability to create seamed chromoly tubesets was the driving factor for the reasoning as to why chromoly tubing became so affordable and widespread in the eighties. It seems to me, since Tange seamed chromoly tubing (like Tange 1000) showed up AFTER it's other tubing offerings (like Tange #3, which is quite similar in size/strength as Tange 1000, but seamless). So seamed chromoly tubing did provide lower pricing, but it did so after seamed chromoly tubing had already shown up. Any arguments to refute my claims (more like guesses than claims really)?

Be careful, guesses can really get you into trouble around here

You invited a response, so I'm going to try and use some bicycle tubing data from Columbus to take a slightly different tack. It’s just easier for me to go through the exercise this way rather than try to follow your train of thought. I apologize in advance for any confusion. I certainly don't know everything, but as an amateur framebuilder (limited so far to brazed lugged steel), I'm pretty familiar with standard tubing dimensions (diameters, wall thickness, weights).

Most bicycle tubing has wall thickness in the range of 0.5mm to 1.0mm in the center (non-butted) sections of the tubes. It can be as thin as 0.3mm (Reynolds 953) and as thick as 1.22mm (18 gauge non-butted 1020 carbon steel used in late seventies Schwinn Le Tours, Travelers, and World Sports). A wall thickness of .08" (2.032mm) would be almost a millimeter thicker than the 1020 steel tubing used in these late seventies Schwinns.

Standard Imperial O.D. for the main tubes in the 1980s (pre-O.S.) were:

Top Tube – 25.4 mm (1”)
Down Tube – 28.6 mm (1-1/8”)
Seat Tube – 28.6 mm (1-1/8”)
Head Tube – 31.75 mm (1-1/4”)

Since the density of all steel alloys is virtually identical, a tube that's twice as thick as another with the same O.D. and length will weigh nearly twice as much.

Columbus SL is a double-butted chromoly tubeset used extensively in the eighties for competition bicycles, and the diameters, butting profiles, and weight of a raw tubeset (not cut to length and mitered by the framebuilder) are shown in the data sheet below.

http://i32.photobucket.com/albums/d7...psd2fa6c6b.jpg

Notice the weight of the raw tubeset is 1,925 grams (4.244 pounds).

Columbus Zeta is a straight-gauge carbon steel tubeset used in the eighties for lower end sport bicycles, and the diameters, butting profiles, and weight of a raw tubeset are shown in the data sheet below.

http://i32.photobucket.com/albums/d7...ps3fe1238e.jpg

The weight of the raw tubeset is 2,440 grams (5.379 pounds), or more than 1.1 lbs heavier than the SL tubeset.

The Zeta tubing has a 0.9mm wall thickness, while SL is 0.6mm in the center part of the tubes and 0.9mm in the butts.

The 18 gauge 1020 straight gauge tubing in the late seventies Le Tours and Travelers had a wall thickness of 1.22 mm, which would add a bit more than a pound to the weight of the 0.9mm Zeta tubeset, putting it at about 6.5 pounds.

In contrast to the SL, Zeta, and 18 ga. 1020 tubesets, the new Columbus XCr for lugs stainless OS raw tubeset weighs 1,425 grams (3.142 pounds), or more than a pound less than SL.

http://i32.photobucket.com/albums/d7...ps6d4437fe.jpg

http://i32.photobucket.com/albums/d7...psc8ffd151.jpg

Of course, these weights are for full length tubing, so the differences between tubeset weights will be less for smaller frames. Also, for practical purposes, let’s specify that the weights of lugs, dropouts, and BB shells will be the same for each frame.

Basically, my point is that the weight of a raw 1979 Traveler 18 gauge 1020 alloy tubeset at 6.5 pounds is going to be more than twice as heavy as a raw Columbus XCr for lugs tubeset and more than two pounds heavier than a Columbus SL raw tubeset.

This thread is wonderful. :)

I think the optimization of tube OD vs wall thickness was in practice more easily approached from the other direction. Pick any one of the commonly avialable tube OD sizes which were available in 1/8" incriments, and then optimize the diameter to thickness by reducing the tube wall thickness. For high-quality tubing, a fairly wide selection of wall thickness was avialable, custom builders will oftern mix-and-match specific tubes from different tubesets in order to finely tune the weight & stiffness of the frame. Much easier to fit OD of tubes into available lugs and to match established aesthetics by sticking to commonly available OD sizes. THe only bike part that cares about the exact tube ID is the seatpost and that is easy to specify (or to ream-out). I think that vintage road bikes largely arrived at using 1" TT, 1-1/8" ST and DT because the tube diameters were fairly well optimized to available CrMo. Even thinner CrMo tubesets were available then (such as columbus KL) but by all acounts made bikes that were too limber with standard size tubes and too fragile to use at larger OD.
Thickwalled hi-ten tube bikes probably suffered a bit from trying to conform to the standard tube OD of nicer CrMo bikes. The hi-ten steel was not strong enough to use as a thinner wall but they were overly stiff and heavy because they used such thick tubing. Probably would be possible to have built a slighlty more optimized hi-ten bike using smaller diameter tubing throughout.
Also note that as steel strength increased beyond that of plain non-HT CrMo, it became necessary to bump up the tubing OD by +1/8" and later +1/4" OD in order to better optimize the strength-stiffness-weight ballance to the material.


I have run across a few older mid-low end bikes that proclaim that they used butted hi-tensile tubing. Interesting to see that it was at all economically viable to produce butted hi-ten tubes to compete in the same marketplace as strait-gauge CrMo.

Correct and a quick sanity check shows this to be true. Let’s look at two tubes of the same length and a standard 28.6mm outer diameter. If you look at a Tange #5, plain gauge, CrMo seat tube which has a wall thickness of 0.9mm you get a cross sectional area of 78.3 square millimeters. Now, if we take a high tensile tube which has an inner diameter of 25.4mm (which is fairy typical), we come up with a cross sectional area of 135.6 square millimeters. Since all steels vary very little in density, the relative cross sectional areas can be equated to relative weight and the CrMo tube is 57.8% the weight of the hi-tensile tube. That’s pretty close to the 60%.

Yes, the difference will typically be less. Even if the manufacturer used a full Tange #5 tubeset, they would probably use lugs and shells that weighed the same or very similar. This will cut down on the weight advantage of the CrMo frame.

The better material frame will probably also have more fittings. The rear dropout will likely have a hanger that adds weight while the hi-tensile frame likely has a hangerless, stamped dropout. The better frame probably has shifter bosses, which weigh less than the cable stops for the stem shifters on the hi-tensile frame. The CrMo frame probably has an extra water bottle boss. Basically, the better frame likely has more convenience fittings which add weight and further compromise it’s weight advantage over the hi-tensile frame.

However, the biggest compromise are the stays and forks. In these applications CrMo’s potential weight savings cannot be fully realized because the forks and rear triangle would be too whippy. Stiffness in a round tube is a function of the material’s modulus of elasticity, its outer diameter and its thickness. In the case of CrMo and 1020 hi-tensile, the modulus of elastic are similar and the stiffness primarily becomes a function of diameter and thickness.

A main triangle can maintain good stiffness, primarily due to the larger diameter tubes. But shrink the diameter, as in the stays and fork blades and things start to get whippy. In order to maintain the necessary rigidity, Tange used CrMo stays that are about 80% the thickness of their hi-tensile stays. So, in these regions you lose about ½ the potential weight savings of CrMo. This is why designers often substitute lesser grade material in the stays and forks. It saves money without affecting the weight as much.

Then there is the whole question of how much the designer wants to push envelope in either direction. Does he want to go heavier than the norm, knowing it is more likely to be abused and used in all sorts of applications? Or can he make it lighter, knowing that it will be used only in certain applications and that the extra cost will result in better care? A designer of an X-mart bicycle is going to build in a heavier safety factor than a standard hi-tensile frame, while a designer of a time trial frame will build in a lot less than your typical CrMo frame.

Back in 1983, Bicycling did a comparison of entry level bicycles. A Pansonic Sport with a full 1020, 21"frame weighed 6 lbs 9oz. An identically sized KHS Citation (notice how I found a KHS for you) with a Tange #5 main triangle, weighed 5 lbs 9 oz. Obviously there will be some differences in weight savings due to actual tubing gauges, geometry, choice of lugs, fittings, etc., but it looks like a roughly 1 lb weight savings by going to plain gauge, CrMo, main tubes over hi-tensile.

Now, here’s the bonus. I found a road on a 1985 KHS Fiero with a Tange 900, seamed, double butted, main triangle. Frame weight was 5 lbs 2.5 oz and it’s a 2" larger frame. So you’d get about an additional ½ lb saving by going butted CrMo in the main triangle.

You’ve missed one very important point of my previous posts. I was referring to the cost saving of seamed butted CrMo tubesets. Butting is the most expensive operation of tube making. While there are savings in going from seamless to seamed in a plain gauge CrMo tube, they’re relatively small compared to going from seamless to seamed in a butted, CrMo tube.

Let’s take a look at the two previously mentioned KHS bicycles. In 1983 a KHS Citation with a seamless, plain gauge CrMo main triangle cost $219. Two years later the KHS Fiero costs only $20 more, yet it’s got a ½ lb lighter frame, thanks to going seamed, butted CrMo. To top it off, the rate of inflation over those two years was about 7.5%, so the adjusted price increase was only about $5. The components were comparable and, if anything, arguably better on the Fiero. They were certainly lighter based on overall weights.

Seamless, butted, CrMo tubes were pretty much restricted to mid-range and higher models. The best you got for an entry level price up to the very early 1980s was a plain gauge, CrMo main triangle. The mid-1980s seamed tubesets brought butted CrMo butted into the entry level. You got the weight savings of butted tubes but perhaps more importantly you also got their more resilient ride quality. A couple of years earlier you would have had to pay a lot more to get the weight savings and resiliency.

After coming across another KHS bicycle this week and was hoping to find more info on via the WWW, I happened across this thread. Even though it's been four or so years, I just want to thank everyone who offered up insights and observations to my questions. I really appreciate all the help and knowledge given without any attitude towards this novice. It creates a great community here on the forum, and I hope that sometime in the future, I get to meet some of you and thank you in person for all good you have graciously given me throughout my years participating on this forum. Thanks once again, you make this the best of WWW for me.

I thought all the early high end steel sets grew out of technology used from the aircraft industry but I could be wrong on this.