Fahrenheit531 

Now that I've settled on three bikes that I really like, riding each regularly, I've noticed they seem to differ in stiffness even though they're all butted 531:

'79 Competition GS is by far the most whippy.
'71 Paramount is still pretty flexy, but less so than the Raleigh.
'78 Volare is the stiffest of the three, but still with some flex.

Is this variability a product of geometry? Brazing technique/materials? Builder's geographic location? My imagination?

Just something ricocheting around my skull on a Saturday morning; science, speculation and/or unfounded opinions are all welcome.

TenGrainBread 

"Butted 531" came in a variety of gauges and butts. That could be part of it.

I suspect the lugset, especially the bottom bracket shell, also has an effect.

Not too mention how stiff the cranks are. That might affect it.

If the geometry differs that might affect your pedaling style and therefore frame flex.

Salamandrine 

Yeah, 531 came in multiple gauges, and if the builder spec'ed a thicker gauge for whatever reason, the bike will be stiffer.

Chainstay crimping and length also affect stiffness, as well as oval vs round, overall frame size, geometry, etc.

Fahrenheit531 

The compounding of small differences. That makes sense. It still amazes me how differently two bicycles can feel and perform when they appear, on paper, to be nearly identical.

Cougrrcj

If you were to put the same wheelset on each bike, that would eliminate that variable. With a properly-tuned and properly-tensioned wheelset, just about ANY frameset feels more 'sprightly', 'responsive' or 'faster' than the best frameset on a junk wheelset. If you don't believe me, just TRY it!

Take the most 'sluggish' bike you have and re-tension the wheels properly. Then you do the exact same ride. Which feels faster or more responsive? You'll also notice the increase in speed and less effort is used to achieve that faster speed.

Wildwood 

2nd @Cougrrcj = tires first, wheels, cranks (when under power), handlebars, seatpost (maybe), etc.

What's the clearance on the FD when in your sprinting gear?

Lots of things make a frame feel whippy or sturdy. Including of course tubeset, size of frameset?

case in point: SLX Merckx Corsa Extra, SLX DeRosa Pro - maybe 1year different, maybe 1cm different. Major difference in feel.
But it may be a case of tube substitutions on large frames, and\or fork differences.

Cougrrcj

Yeah, tires, too. I almost forgot that. I had bought my '86 Miyata 710 used, with cheap tires. It rode like crap. Turns out the PO had put one of those very thick/heavy 'thorn-proof' tubes in the front in a 23mm tire. When I replaced them with lighter/more supple 150tpi tires, it felt entirely different. The puncture-resistant tube alone weighed more than my new tube/28mm tire combo.

samkl 

A fellow on the Internet-BOB message board uses some kind of ultrasonic device to measure the wall thickness of tubing. He created a spreadsheet with the results for all sorts of bikes. Check it out.

Slightspeed

I have 2 Raleigh Super Course bikes, a '73 and a '78. Both are 531 3 main tubes, and same size, and similar gearing. Both have great ride quality, yet the '78 feels more lively, and seems to have a lighter, more racy feel, where the '73 has kind of a "Cadillac cruiser" type of ride. I love them both, and think the change is mostly due to different geometry. Viewed side by side the frame differences are slight, but it probably doesn't take much. I've never taken the time to take measurements, except seat tube length and handlebar reach, for fit, mostly. Some day I'll get around to comparing actual measurements. From the below pictures you can see how different the tire diameter is to the seat tube, like the gold '78 is more upright. Both bikes have 700c x 28 tires. The seatstay to seat tube angle looks a lot tighter on the gold '78, which leads to shorter chainstays. I keep meaning to swap wheels, to see if the tires make that much difference. Gearing is the same, except for the triple on the '73.

The '73 "Cadillac cruiser".

The "racy" '78.

mstateglfr 

I've seen that before and have to question the accuracy, based on a few of the frames I know.
If what's listed that sound wrong is actually accurate, I'm shocked.

samkl 

What looks wrong to you?

clubman 

The absolute lack of consistency with the tubing specs perhaps? Doesn't seem possible.

repechage

ok those two bikes may share a brand and model name but are apples v oranges
they Should ride and behave differently.

one item to note is the variability of assembly quality that you cannot see- beyond overheating of tubes and or gaps in the brazing, the quality of the tube metering or on a production bike notching can vary widely.

Salamandrine 

A quick check with pixelstick (mac app) plus my eyeballs says the '73 looks to be 72ª parallel vs about 74º for the '78. That's just from the photo. An actual protractor would be needed for accurate measurement. Even with that rough info, it explains the different feel. Early 70's bikes were meant to be able to handle gravel, as pro racing at that time still had gravel portions. I like 72 parallel bikes. They do have a cadillac sort of ride typically, but aren't quit as intuitive if you're trying to really shred a descent.

That's geometry and handling though, which is a different thing than stiffness. Stiffness differences are frankly blindingly obvious with a short test ride. I suppose as a mechanic I test rode thousands of bikes. I feel that I have a pretty good understanding of the differences. The stiff bikes just get up and go quicker. Flexy bikes feel heavy even if they are very light, and generally respond like a wet noodle.

repechage

But Jan states they "plane"...

I too got to ride a bunch, mfg differences are just there. There was a California Masi that the shop could just not sell, decent size 58cm as Masi measured. I rode Masi bikes exclusively at the time, this one just felt Dead. Power zapping even. That was the only one like that. Weird. Would have been interesting to remove the paint and look for "cooked" tubes.

samkl 

It seems generally correct to me. I assume whatever device he's using can't be totally accurate to 1/100th of a millimeter. Add in manufacturing tolerances, paint, rust, who knows what else, and it seems plausible.

mpetry912 

Seems like Bicycle Quarterly did a test with 3 identical frames using different tubes and the riders could tell the differences. It was a good test methodology that eliminated most of the biases. Bikes were all painted blue, just numbered 1,2, 3.

The frame design - angles and dimensions - as well as the tubing guage, wheels, and tires have a far greater impact on ride feel than does the type / manufacturer of the tubing.

Mark Petry
Bainbridge Island, WA USA

Fahrenheit531 

Thanks for saying that much more concisely than I was about to.

All the non-frame variables discussed above impact the overall ride. I think we all get that. I've swapped wheelsets, tires, saddles and posts, all kinds of stuff between my bikes out of curiosity or in pursuit of some elusive noise and yes, the ride changes. What doesn't change is what I'll call the "elastic response" of the frame itself (most obvious when, say, charging up a hill or aggressively taking off from a standstill). And that response, even in frames of the same size and material, which is what I've got over here, is what interested me.

I had no idea lug choice made any difference, for example. Always figured they were selected for aesthetics, along with maybe weight, and that was it.

Doug Fattic 

As a frame builder I've learned that the stated specs on any tube and their actual measurements are often different. In the old days when using Columbus SL was a popular choice, I would weigh each chain stay and they would vary from 145 to 175 grams each. I could then pair the common weights together and select which pair would better fit a customer. Another common variation is that a tube's wall thickness does not agree with whatever it is supposed to be. It can vary either a little more or less. And again another common difference between tubes of the same manufacturer and model is where the butt is located within the tube. It can be off by over 10mm. Furthermore manufacturers purposely make tubes with differing butt lengths and steel hardness for different applications.

To add another variable beyond these manufacturing variables is that the builder can choose where to miter the tubes in relation to the butts. I teach my frame building class students to mark where the butts are located and roll them on the flat table to find where any curvature may be located before mitering. They can be bent up to an 1/8th of an inch. Some builders locate the long butt at the head tube while others on the other end and some pay no attention at all. Lots of variables.

The Golden Boy 

There was the Bruce Gordon article:

Tubing Article ? Nothing is better than a bike that fits

The Golden Boy 

I’ve run across this with “similar” bikes-

To my way of thinking, in comparison- a bike with CrMo stays and fork should feel less “compliant” and ride “heavier,” if not more “stiff” than a bike with 531 stays and fork-

While they’re not identical- the geometry is similar between the 1985 versions of the full 531 framed Trek 720 and 531/CrMo framed Trek 620. I would lay money on the 620 feeling lighter and riding lighter and feeling more compliant than 531c 720. Again, I recognize it’s not an apples to apples comparison-and that 531c is SUPPOSED to be stiffer than the average bear. I would just figure CrMo chosen for a touring application would be heavier.

Ive also noticed this between my 1978 Trek TX700 and 1978 Trek 730 frames. Of course, there should be a difference- I just figured at this time DB531 was DB531- the 730 is light and compliant- I expected the TX700 to be like that, but longer- this smoother and more stable. I even initially built the TX700 almost entirely from parts off the 730- the TX700 is noticeably more stiff- from the fork to the frame than the 730. Any difference in the wheelbase or chainstay length wasn’t reflected much in the “give” of the ride. IMO and all that.

jeirvine 

Great post.

One of the things I love about old steel bikes is how many variables there are, just in the frame/fork.

martl

i've noticed that the presence of the small bridge between the chainstays can make a huge difference in how stiff a bike feels.

Last ride 76 

Funny, different generations I guess. This is the one I remember Where the riders could not correctly identify the differences...https://www.thetallcyclist.com/wp-con...Seven-Test.pdf(link from thetallcyclist.com, and crediting habanero cycles with providing it)


Seems in this test that similarly built bikes using different tubing were sufficiently similar in ride as to not be reliably distinguishable from each other.

mpetry912 

Had not seen that one but thanks for sharing it. Tubing choice is an ongoing discussion with no clear answer, except "It all depends". I personally think (and I think an objective read of the articles does confirm) that other factors like tubing guage, frame design, tires and tire pressure have a lot more to do with how the bike feels than whether its Columbus, Reynolds, Tange, or other tubing.3

My new Mark DiNucci built "Allez 2.0" uses a special 853 tube set drawn specially for this bike, with very thin wall forks and stays and a somewhat unconventional frame design with a very relaxed head tube angle. Several forum members have ridden this bike and will confirm that it's unlike any other steel bike they've ridden.

So, steel still has some surprises in store for us, marketing trends be dammed.

Mark Petry
Bainbridge Island, WA USA