cudak888 

P.S.: As for the Basso, the previous owner kinked the top and down tubes. Guess I'm stuck getting another frame.

-Kurt

OLDYELLR

As an engineer, that was also my understanding. The tough part is determining under what circumstances this limit is exceeded on a bicycle frame. I'd guess that a frame that has been well maintained, protected from corrosion, not abused or dinged, and, of course, properly built in the first place, should last virtually forever.

Artkansas 

I have a early 70's American Eagle/Nishiki. I've owned it for 30 years now and put something like 40K miles on it and don't notice much difference in the ride. Steel is real.

Lewis72

Well, I have a degree in Mechanical Engineering (read Physics. They don't differ too greatly). Also, I do a lot of structural analysis as part of my job.

What has been stated here Re fatigue earlier is correct: steels DO NOT go soft over age. The saleman was talking tripe. It would have been interesting to hear his response when asked about the Young's Modulus of steels (they're all much of a muchness), Endurance Limit (as mentioned earlier in this thread) and even throw in a bit of Creep or Stress Relaxation (only occurs in steels at temperatures a cycle frame will never see in service) for good measure. A google search on these terms will probably explain them clearly.

Young's Modulus: This essentially defines how stiff a material is ignoring its shape. For steel, this will not change over many, many years. Only if the steel is subjected to very high temperatures or in yield (ie being permanantly bent) will the properties change.

How many times does a car wheel get loaded & unloaded? Hundreds of times a minute when driven.
Have you ever known one go soft? They'll only break or bend if you hit something very hard. Usual use they'll go on forever. Same with bike frames.

merlinextraligh

Unlike steel bikes, Golf clubs actually do wear out. Over time the grooves on the face of the irons wear thin and get more rounded decreasing spin on the ball, so you do owe yourself new golf clubs.

Dave Moulton

When steel is bent back and forth as a frame is when riding it actually becomes hardened and therefore brittle which is why it eventually breaks. Steel does not, and cannot become softer.

Having said that a quality steel frame can last fifty years or more depending on the amount of use, so a frame 15 years old has many miles left in it. Also a steel frame rarely fails suddeny; a crack will appear first and the frame will feel more flexible than it should be giving you fair warning. In most cases it will get you back home even with a crack in it if you ride carefully.

lotek 

just as a counterpoint,
I went into LBS yesterday for a new chain tool (I actually broke mine) and the 20something
wrench says "Marty, you've got to see this old Pinarello" (he mentioned the bike to
me before), brings me back to see this fantastic olive green 1975 Pinarello, one owner full
campy bike that was in for yearly maintenance and new pedals.
The wrench and I the proceded to discuss vintage steel which most of the mechanics
in the shop either lust after, are persuing, or ride.

Marty

OLDYELLR

To expound a bit on what Dave said, a properly designed and built frame will flex under use, but this flexing will be well within the steel's elastic limit; therefore, the steel will not be premanently damaged. I don't know what the design criteria for bike frames is, but in civil engineering, steel structures are designed with a safety factor of four, i.e., they are stressed only to a quarter of the steel's elastic limit under the maximum expected load. Under these circumstances, the steel will only fail as a result of corrosion damage or catastrophic damage, such as a collision. Another example, if you have a wire coathanger and only hange shirts on it, it will maintain its shape and last forever. However, hang a heavy coat on it and it will bend and not spring back because it has been stressed past its elastic limit. Bend it back and do this enough times and it will eventually break. Similarly, if you cold set a frame to change the rear spacing, you have stressed the stays past their elastic limit. There is no harm done, but if you repeat this hundreds of times, it will break. Perhaps the same thing can take place when riding a bike repeatedly on very bad roads and crashing it often, but this would not be normal. Looking at John E's frame failures, both cases could be the result of some sort of damage when the frames were built. I've always considered denting chainstays for tire and chainwheel clearance a very crude operation, better suited for cheap lawn chairs. These indentations have to be the weak points of the tubes. (The best bikes I've owned had round/oval or round/oval/round chainstays.) I'd be curious to know exactly how the bottom bracket shell failed. I suspect many frame failures resulted from poor brazing, either overheating, or poor braze metal penetration.

aadhils

I wonder when this bike had reached its fatigue life....50 years ago? And Sheldon Brown still rides it too...oolala...
https://sheldonbrown.com/ranger.html

OLDYELLR

Not likely Sheldon's bike frame would fail due to fatigue. It's built like a tank. It's some bikes built generations ago using very thin tubing in the quest for ultimate lightness that are more likely to fail. Nowadays you can find 15 pound bikes made of exotic materials, but I've heard people claiming they had 15 pound bikes in the fifties (undoubtedly stripped to fixed wheel configuration). I doubt if some of those are still in one piece.

Vo2min

I love the ride of my steel bikes, and my old 85' Centurion Ironman is still going strong. But can someone explain, if steel lasts forever, how the springs in automobiles weaken? All the guys back in the 60's and 70's that had old Plymouths would need to get their rear leaf springs "re-arced" when they sagged over time. Note that they don't break, but lose their "springiness". Is this the same as a steel frame going soft?

alanbikehouston

The "myth" that a steel frame can "wear out" or "go soft" has been around for about a century. And, of course, it is nonsense. The downtube of a 1975 Paramount has exactly the same stiffness and strength today that it had thirty years ago.

"Bicycling" had a discussion with some designers where some possible (but rare) exceptions were mentioned. A frame with a massive amount of internal corrosion that "thinned" out the walls of the tubes. A frame that had cracked. And, of course, a frame where the tubes were not properly joined when the frame was built.

This myth was so powerful that many Pro teams in the 1970's would give riders new bikes in March, May, and July...because the "myth" said that the March frame would be soft and flexy by July. The "worn out" bikes were sold off cheap. And, I suspect that there are folks riding happily today with some of those "used up" Pro bikes that are now more than thirty years old.

OLDYELLR

I've had leaves in leaf springs crack and coils break in coil springs. The reason, I believe, is that automotive springs are very highly stressed compared to bike frames. There is also damage from road salt and rocks getting lodged between coils. The reason for those sagging springs is probably because the heat treatment was on the soft rather than brittle side for safety reasons. A few years ago a manufacturer was recalling minivans because a front spring could crack, digging into the tire. Obviously, a spring that merely "sagged" would be deemed safer.

Blue Order

Steel doesn't wear out. He's full of that stuff you see in cow pastures all across America. So full his eyes turned brown.


Yeah, you walked in the door. Something I no longer bother with.

teambhultima

OK, so here's a point to consider...

The rear suspension springs on my 1967 Alfa Romeo are shot. And they are Italian! So, if these can wear out, as many automotive springs do, can a steel bike frame wear out eventually, or will we never hit the "fatigue limit" described above? (Good reference, thanks Scooper, plus I like your chrome Schwinn Paramount.)

I gladly volunteer for a scientifically controlled experiment. Send me your old steel-framed bikes. I will ride them a lot and try to wear each one out. I'll even rotate between bikes so as not to spend too much time on any particular frame or manufacturer. Please don't send blank frames - send only complete bikes - as I'll be too busy conducting this valuable data-gathering experiment to swap components from one frame to another.

Thanks in advance to all those willing to help. I'm on my way to the FedEx building to await your shipments!

cudak888 

I volunteer as well. I am willing to take in frames only, as I have sufficient parts to build each up for testing, and am willing to swap parts if nessesary.

Contact me for shipping address.

-Kurt

(And no, I'm not joking )

John E

Which model do you have? My 1971 Semi-Pro finally broke at about the 40k mile mark.

John E

The seat tube lug broke away from the rest of the BB shell. Others have suggested internal corrosion as a possible cause. This is evidently a common failure node on older Japanese frames.

I concur with your observations regarding the Peugeot and the clearance dimples.

Dogbait

...and the little voice told me; "you've read of this somewhere".....

And here it is:

Those old soft frames

Dogbait

jimmythefly

Idiot! Any good salesman would have gladly helped you modernize your Pinarello. The bike shop would make more through selling you modern parts vs. a whole modern bike, especially if you have them do the install and charge you labor for it.

Deanster04

I have a 1969 Cinelli SC that I still regularly ride. Just as good as the day I bought it. Have replaced the normal wear items a number of times but the bike is still 10 spd (2X5) and rides like a charm. The bikes has more than 100K on it (don't exactly know never had a odometer) but, the bike is still extremely sound. I just completed a complete rebuild and the frame was still in excellent shape. If you like your Pinerello (lugged I assume) go for it. I have a number of bikes from the Cinelli to a modern Dean el Diente CTi. Still like to ride the older steel bikes (lugs), a little slower especially in the hills but at my age who cares. Unless there is an identifible damage to the frame you shouldn't worry.