Custom Frame Materials & the Builder’s Advice

It never fails that a customer that wants a custom bike also wants to pick the tubeset that bike is built with. And for good reason – they’re paying a lot of money and deserve to get what they want, right? Well, sort of. As a frame builder, part of what they (customer) are paying for is my knowledge, which includes tubesets. Why? Because the bike has to ride as good (or better) than it looks. Or else it’s just wall art. Instead of going on and on about this Reynolds this or Columbus that, let me educate you with a small piece of history, that way when I say “trust me”, you’ll know why.

The following article was written by John Schubert for Bicycle Magazine in 1987 and has been rewritten here for your reading pleasure.

Steel vs. Steel

Ever wonder what a difference the brand of steel makes in a frame? Find out in our blind comparison between Tange Prestige and Columbus SL

We spend endless hours pondering an old question: what are the actual performance differences between different steel tubesets? What is the rider’s real preference and how much is swayed by pretty decals and advertising? And what have the new developments in steel really accomplished?

Once upon a time, I was pondering these questions with frame builder Bruce Gordon and Shimano’s John Uhte, who promotes Tange tubing through the Shimano-led JNM group of bicycle component manufacturers. Uhte was frustrated: Tange Prestige, the company’s flagship tubing, is a stronger, lighter alloy than most bike steel, yet it wasn’t getting the publicity he felt it should. Many of us have respect for the qualities of Tange Prestige, but we didn’t have much to say about it except that it ultimately produced a frame a few ounces lighter than conventional tubesets.

“What about a blind test in a magazine?” Uhte suggested. “Bruce here will build two bikes. I’ll throw in the Tange tubing and components. You write it up. You won’t know which bike is which. Write it the way you see it.”

Thus a great idea was born. Columbus SL was nominated as the baseline tubeset. Uhte supplied the Prestige and the Shimano 600 components. Gordon built 2 frames. Some months later, two bikes, identical to the eye but the color, appeared at my door. The bikes, by the way, are absolutely beautiful. Of all the custom frames I’ve seen and ridden, these are the very best. The metalwork is absolutely flawless; the stylistic touches elegant and tasteful. The photos show that better than words can tell.

The baseline tubing, Columbus SL, is popular with good reason: it works. It’s chromoly steel alloy doesn’t distinguish it from many other bicycle tubesets, but Columbus SL wins “the one to beat” designation because its metallurgy and physical dimensions have been verified and reverified by rider preference, instrumented bike test and that sincerest form of flattery: other tube manufacturers from all over the world, including Tange (in their No. 2 tubeset), copy it.

Compared with SL, Tange Prestige is more expensive and has superior metallurgical performance by dint of special heat treatment. What performance benefits do we get from that? Prestige weighs the same, volume for volume, as any other kind of steel. It is also equally stiff – one rule of conventional metallurgy is that all alloys of a metal share the same modulus of elasticity, and that modulus cannot be changed by adding alloying ingredients or by heat treating.

Prestige is, however, much stronger and somewhat harder than non-heat treated steels. Tange’s brochure says it has 30% more tensile strength and 12% more surface hardness than either “C Company” or Tange’s own No.2 chromoly tubing. These qualities have been verified by every frame builder I’ve talked to. It bends and cuts less readily. “It’s an SOB to cut in the machine,” Gordon said. “And when you align a fork, it takes more tugs to move the Prestige fork blade. You have to yank harder to move it or is springs right back.”

This extra hardness doesn’t help the rider any – it just gives your frame builder something to talk about. But the increased tensile strength allows Tange to reduce the wall thickness, and hence the weight, of the Prestige tubeset without compromising durability or crashworthiness.

Other than high strength, ultralight tubesets have appeared before. Reynolds 753 has been around the longest; Ishiwata, Vitus, and now Excell also have them. However, Tange Prestige is the only one that’s been a commercial success. It’s been marketed well by the Shimano juggernaut and it comes in a variety of wall thicknesses, including some excellent configurations in mountain bike tubing. And, unlike Reynolds, you don’t need special factory certification to build with it; it can be assembled as the builder prefers – brass or silver brazed, welded, lugged or lugless. Its surface hardness is less severe than that of other premium tubes, so it’s not so difficult to machine. Uhte says that’s due to Tange’s non-oxidizing computer controlled furnaces.

The book says that the reduced wall thickness will make the Prestige tubing less rigid. For the midsection of a 1 1/8” down tube, skim 0.1mm of wall thickness and you lose 16% of your tubes rigidity; skim 0.2mm and you lose 32%. The rigidity loss is favored by many riders for its effect on the way the bike feels on rough roads. Some cyclists bemoan any lost rigidity for climbing, and others say it doesn’t matter. That particular debate will never end.

Of course, the skinnier tubes will reduce the weight a bit. Gordon said that on the finished frames, the weight difference was an insignificant 5oz (about 148g) – one third of a water bottle. Our Tange frame had the same wall thickness as the Columbus SL frame in the seat tube (0.9/0.6mm) and fork blades (0.9mm), and skinnier walls everywhere else. The Columbus down tube was 0.9/0.6/0.9mm, Tange’s was 0.8/0.5/0.8mm (that was Gordon’s request: most Tange Prestige frames are 0.1mm thinner than that). The Columbus top tube was 0.9/0.6/0.9mm: Prestige 0.7/0.4/0.7mm. Chainstays and seatstays were 0.7mm for Columbus and 0.6mm for Prestige.

Tiny differences, five ounces of metal stretched out over six tubes. And when I rode the bikes, I hadn’t been told which was which. And yet, there was a definite difference between the bikes and it took little time to notice. Once when I went on a side by side with Imre Barsy, our former industry editor who now works at Specialized, he took all of 100 yards to notice the differences and voice his preferences for the pink bike.

Barsy’s preference was due to the single most striking difference between the bikes: the pink once seemed to transfer fewer vibrations to the rider. The minute vibrations that result when you roll over a slightly rough asphalt road are a source of fatigue and bother. They were much , much lighter on the pink bike.

Indeed, I preferred the pink bike too. In addition to feeling smoother over minor pavement roughness, it had a lighter “feel” to it. I should set this difference in context – it was small enough that you couldn’t detect it except by comparing two identical bikes. Once, I replaced the Specialized Turbo S tires with a slightly pudgier set; it resulted in far greater change in riding qualities. Other, smaller changes, such as a padded saddle or padded handlebar tape, would have muddied the waters too.

And yet, the pink bike’s list of small but discernible advantages grew. It tracked the pavement better on my favorite descent – a steep nine percent grade with potholes, lumps and patches in the pavement. This demands white-knuckled bike handling to be a very challenging test (I’ve clocked 43 mph there with my Solar Cateye). The pink bike felt more secure on this hill – a difference you’d never notice on smoother or less steep roads. When the aqua bike went over a bump, it took longer to regain full weight, traction, and control on the front wheel. The pink bike felt more inclined to stay glued to the road.

One place where I didn’t notice an advantage was on rougher surfaces. On roads where the asphalt mix uses especially large stones, the pink bike’s slight comfort advantage was lost, and both bikes told the rider all about the poor pavement underneath.

I could detect no difference in climbing. I rode both bikes up a 21% grade, among lesser hills, and both got to the top in better shape than I did. We know from our calculations that the Prestige bike, whichever it was, had to flex more, but it didn’t seem to matter much in practice.

From all these findings, I assumed the pink bike was the Tange bike. It rode a bit nicer and felt a bit springier. Must be the lighter tubing, Barsy thought so too.

Now, may I have the envelope please?

The pink bike, the one Barsy and I preferred was the Columbus SL bike! Builder Bruce Gordon wasn’t surprised. “Louis (BG Cycles Plant Manager at the time) agreed with your preferences. He rode the bikes and liked the pink bike better. Said it just felt a little more right.”

Uhte was surprised. He mentioned that the beefier Prestige down tube specified by Gordon may have hurt his cause. “I’ve had lots of reports of 0.7/0.4/0.7 down tubes give an especially smooth ride,” he said. He added that Tange is investigating the possibility of lightening the fork blades to 0.8mm to increase shock absorption and reduce vibration.

Another interested party was John Kennedy, the country’s exclusive Tange distributer. “What you say is contrary to what all the builders I sell to say,” Kennedy said. “You’ll stir up some controversy and get some letters. I get comments that it smoothes out the road better than Columbus, and it’s stiff where it needs to be. It does well in the hills, yet rides smoothly over rough roads. The people using Prestige just love it. I have had both Columbus SL and Prestige frames, made by different builders. I agree with what I hear – that would be my judgment.”

So how do I reconcile my and Barsy’s wrong guess? Our logic must have been thrown off by something more fundamental than tubing gauges. Was a dynamic vibrating mode the culprit? Any mass, such as bike frames, has various frequencies at which it stores energy and resonates, and other frequencies at which it dampens vibration. Changing the mass changes the frequencies. It’s a complicated question because the frame has several major vibratory modes; including front fork, fishtailing, and something call the hammock effect. The front and back ends of the frame can have different vibratory modes. The coupled resonances of the frame and fork can interact. Only a massive research program could sort through this complicated network of vibratory modes.

I was astonished. I was so sure the pink bike was Prestige. Maybe the flashy color influenced me. No, that’s not it. Maybe my build was better suited to the SL bike. It was a 54cm bike and I’m 5’8” and 155lbs. Other riders, other frame sizes and other wall thicknesses are going to yield difference preferences. True road racing ectomorphs may be better served by the lighter frame.

In any event, the results of this comparison, hair-splitting thought they may be, proves two points: first, building a frame out of lighter, more flexible tubing doesn’t necessarily increase ride comfort; second, that small differences in frame flex may not be noticeable while climbing. The results also speak much about the current state of steel frames. The gauge of steel frame tubes has been refined over many decades, not by any sophisticated structural analysis, but by using the simplest and most sensitive of computers: the human body. Trial and error and many thousands of miles ridden have yielded tubing gauges that deliver a remarkably good ride. I think it can be safely said that improving the traditional steel frame is neither simple nor easy.