Is there a science to building metal bike frames?

[qnz]

There are a lot of bespoke steel and titanium bike builders out there now-a-days. How do you differentiate between all the builders and trust that the shape, material, and geometry they choose is better than the next company?

With carbon frames from big name companies, they test the frame in wind tunnels and have teams riding the frames to provide feedback.

Is there the same kind of testing from smaller builders? Can Joe Welder build the same quality frame out of his garage as Big Name Company Here if he copied the geometry and used the same tubing?

[joevers]

Ride quality of a steel frame comes mainly from the tubing blends and outer diameter. Other things that play a role are construction (lugged, brazed, welded), tolerances and geometry. Geometry is the big one imo.

Take for example my Ritchey Swiss Cross. If you used the same tubes (or at least similar steel type, similar wall thickness, and the same outer diameter) and you build it with the same geometry, I think they'd ride pretty indistinguishable, whether built by Tom Ritchey himself or someone's third frame. Of course this assumes you end up building it to within the same tolerance- though I'm not sure tolerance has much of an effect on ride quality. There's a Richard Sachs post on F10 I believe about the time he got a surface plate and decided to check his earlier frames to see how close to straight they were. They weren't. At all. And that's not uncommon, and I believe he doesn't even check anymore because it isn't worth it to him.

A lot of what you're paying for is the design and geometry, the finish, and the features a frame has. You're paying for the experience of the builder to design a bike *for you*. To pick the tubing, the diameters and shapes, the geometry, and to put it together professionally. Firefly will even butt tubes for you. Yep, that's why they're 5,500. Even then, I'm not sure there's much science to it aside from butted tubes ride nicer and they're as light as they can be.

I was reading a Richard Sachs post the other day regarding why someone would pay for a Richard Sachs and his response was something along the lines of- If I could automate this, I would. If a machine could make these bike they'd be indistinguishable. But a machine can't, so you have to buy it from me, and this is what I charge.

Another good one is from Dario Pegoretti, that "I am just a blacksmith". Someone on one of these forums has it as their signature I think. It's really just that, he just happens to be repeatably good at putting frames together, and people overwhelmingly seem to like his geometry, tube choices, and paint.

[Kirk007]

art and science. The great builders figure out where to put the rider between the wheels, what tubes and geometry to choose for the rider's desired type of riding. That's the science. And different "scientists" have different opinions.
Just to pick three, compare an English to a Kirk to a Pegoretti.

The art is in the welding or brazing, getting the frame straight and everything aligned and doing it over and over again for rider after rider. And then there are the flourishes, and the paint.

You can't go to Specialized or Pinarello or Trek etc. and tell them exactly what you want the bike to do and on what terrain. You can with custom metal builders (and carbon for that matter). And your not wondering about what voids etc. might be inside those swoopy carbon tubes that came out of a mold from some factory that you've never been to nor can go to.

[nmrt]

As much as I liked to spend my money on metal frames from quality builders (Moots, DeSalvo, Seven, Engin, T-Lab, Merlin, Dean, BlackSheep, No22) that I have owned, part of me realizes that if I were blindfolded, I could not tell the difference between these different bikes from different builders had they had the same geometry. As I said, I could not. Maybe someone else could.

As I see it, after a certain point among quality builders, it is not about the quality of the frame itself and the ride attributed to it, but rather an ineffable romance between you and that bike. It is a game of the heart and not the head.

I know there was a study in the 80's with steel frames that proves my point. I will let someone else find that study.

[zmudshark]

Originally Posted by nmrt

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I know there was a study in the 80's with steel frames that proves my point. I will let someone else find that study.

The study proved it was the builder. In that case, Mondonico.

I have owned more than a couple steel frames and more than a couple of the same model. Sometimes the builder has a good day, some days the builder transcends.

[cgates66]

Originally Posted by qnz

There are a lot of bespoke steel and titanium bike builders out there now-a-days. How do you differentiate between all the builders and trust that the shape, material, and geometry they choose is better than the next company?

With carbon frames from big name companies, they test the frame in wind tunnels and have teams riding the frames to provide feedback.

Is there the same kind of testing from smaller builders? Can Joe Welder build the same quality frame out of his garage as Big Name Company Here if he copied the geometry and used the same tubing?

More or less, yes, assuming Joe Welder has the jigs to keep everything straight and is a similarly-skilled welder. There is nothing magic in the welding (steel, at least). If you use the same materials, same geometry etc. - they'll be the same.

If you get into custom geometry or exotic materials, then it's a different story. Worth noting, that two builders may propose different geometries for the same rider and the same requirements. There is judgment here, and beyond judgment, preference.

In all of this, the only thing I know for sure is that bare metal is faster than red.

[GregL]

Originally Posted by nmrt

I know there was a study in the 80's with steel frames that proves my point. I will let someone else find that study.

http://www.thetallcyclist.com/wp-con...Seven-Test.pdf

[duff_duffy]

http://kirkframeworks.com/2012/02/27...esting-or-not/

This is why its worth going with quality builder in my opinion. Design, build, test and back to beginning. This is how you do it. I say its science and art.

[bicycletricycle]

Bicycles are not rocket science, metal bicycle especially. Best practices are relatively easy to follow.

[bikinchris]

The irony is that big companies making carbon frames can't experiment with different geometry very easily. I would cost tons of money to make each set of new molds for a one piece frame.
The reality is that the big companies are copying geometry that steel builders have used for decades.
The really great steel builders are artists more than anything else. They work in metal instead of marble or clay.

[parris]

Bikinchris,

You hit on something with what you said about geometry. If we look at old catalogs in many cases we'll see very similar if not the same geometry has been used for decades to good effect.

GOOD custom builders do a great job with cyclists that have fit issues due to size, injury, body type, etc. They also will listen to what the cyclist wants ride quality wise in their next bicycle and tweak the geometry to give it to the cyclist. There's tons more of course but your comment was pretty spot on.

[qnz]

That was a good read about the Mondonico frame test.

So the writer couldn't tell the difference between some of the frames, and if he did the test over again, he would probably pick different frames as winners.

What about different geometries? Same material frame, but a 73* seat tube here, extra 10mm top tube there, and this bottom bracket instead of that bottom bracket. Would the differences be just as subtle?

[martl]

Originally Posted by qnz

With carbon frames from big name companies, they test the frame in wind tunnels and have teams riding the frames to provide feedback.

Let me correct: the big brands have the marketing budget to rent a wind tunnel and shoot a few nice pictures for the ads, and pay some. Dude to write some cattle manure "study" why their design will save you any amount of watts, and they can sponsor a pro team.

[BdaGhisallo]

Originally Posted by qnz

That was a good read about the Mondonico frame test.

So the writer couldn't tell the difference between some of the frames, and if he did the test over again, he would probably pick different frames as winners.

What about different geometries? Same material frame, but a 73* seat tube here, extra 10mm top tube there, and this bottom bracket instead of that bottom bracket. Would the differences be just as subtle?

I recall reading of a blind frame test back in the 1980s when Columbus was introducing their SLX tubing, a stiffer version of their ubiquitous SL tubing. They built otherwise identical frames and very few (pro) riders could tell the difference.

I also remember reading about some 7-11 pros being unable to differentiate between tube sets in otherwise identical frames and that Davis Phinney, said to enjoy stiffer frames as a sprinter, actually preferred a frame that measured as being less stiff than one that he rejected.

[Jef58]

I think the science is in the geometry that the builder suggests for you. Most times the customer is picking someone who is aligned with a builder's philosophy on how the bike will ride. That is the reason I chose Bixxis. The experience and ability to take a few basic measurements and get it right. Doriano does have a particular platform, mechanical shifting, skinny tire, racing bike. Though he just added the gravel model... When you buy a Sachs, you are buying a bike that has been relatively unchanged and the customer is seeking that as compared to a Sarto where the customer has a lot of input and control of the final product.