motorapido

Short of rust, and short of flawed or faulty brazing, can a steel frame last nearly indefinitely? Mine is 39 years old, with many tens of thousands of miles on it, including 15,000 to 20,000 miles on rougher-then-paved road rail trails. I've always stored the bike indoors. I've ridden in lots of rain, but early in the frame's life I had sprayed frame saver all over the insides of the frame. I'm wondering if when a steel frame breaks, it breaks due to the manifestation of a factory brazing flaw or internal rust. And if a steel frame makes it for so many years and you can assume that there are no brazing flaws and the frame has no internal or external rust, will it go on nearly forever?

My only concern is that I cold-set the rear triangle about 17,000 miles ago. I'm sure that stresses the joints at the chain and seat stays and brake bridge. But so far, so good. Thoughts?

gregf83 

Sure, if you don't ride it. Mine lasted 8 yrs or so before cracking on the bottom bracket. A Colnago steel frame. The bottom bracket cracked.

cny-bikeman

My thought is that the question is silly. If we say yes, does that mean you ignore anything that indicates the frame is failing because you have our assurance? Or if we say no do you stop riding it for fear that it will fall apart during a steep, curvy descent? There's simply no way to tell. My Motobecane frame failed by the rear dropout cracking just above where the axle sits. Not a brazing defect or rust, just one of those things. Replaced on warranty, but I never liked another bike as much as that Grand Jubilee.

FBinNY 

Yes and no, and the answer is a bit ironic.

As a general rule, the pricier a steel frame, the shorter the service life. That's because pricier frames are built closer to the wall, with overbuild sacrificed on the alter of minimum weight. OTOH - low end generic frames don't worry about weight the same way and therefore are significantly overbuilt.

Lastly, forever is a long time, so while you may not need to fret over service life, there's no assurance that any one frame will outlast your attention span.

AnkleWork

Absolutely no one in the world can know in advance the fatigue life limit of that frame, but you can discover it by riding long enough.

fietsbob

Dutch Opa/Oma bike are literally grandfather's and grandmothers bikes still being ridden ,

occasionally thrown in a Canal, pulled out, cleaned up, and re used by succeeding Generations.

motorapido

I appreciate the responses. I should have also included info that I weigh 150 and the frame is a Schwinn-badged Panasonic 4130 frame (1976 Super Le Tour 12.2). This is definitely not an ultra-light steel frame. I do understand that a question of this type invites nothing but general speculation and theory. But I had also wondered if any manufacturers or Sheldon Brown types of people might have created some sort of collection of frame failure data that would point to objective statistics on more and less frequently occurring failure types and even information that might indicate that if a frame passes the xxxx thousand mile mark, an inherent manufacturing-flaw-induced frame failure would typically have occurred. This would be similar to human mortality tables that indicate, for instance, the likelihood of living to 100 if you have already made it to 75. I become curious about this type of thing, despite knowing that my results not just might, but WILL, vary.

I will be quite sad when this 1976 frame, which I bought brand new from the local Schwinn dealer with my paper route money, fails -- if it fails before I do. At the same time, it would give me the excuse to buy me a nice new titanium touring frame. I'm devoted so much to the old girl that I can't get a younger girlfriend on the side, so I'll stick with her as long as she is roadworthy.

Off I go on Sunday on a century ride, followed by a 450 mile tour staring on Tuesday. My Super Le Tour and I have had a happy 39 years together.

FBinNY 

I can't speak for that frame in particular, and in any case it's impossible to reason from the general to the specific.

BUT

Steel frames very rarely fail when there's no upset (dent, buckle or bend) from a high impact. It does happen from time to time, especially in highly stressed top end frames, but even that is rare. I'd be perfectly comfortable riding that bike if it's never been crashed (with visible evidence), and I weigh quite a bit more than you do.

So, I could almost say steel frames last forever, but it's not quite true. So while they have near in finite lives if nothing major happens, the only sure way to never have a frame crack is not to ride a bike at all.

WizardOfBoz

Those are good frames. Bike mfrs consider three properties in a frame material and construction. First is ultimate strength. That's the ability to take a one-time load. If you design a steel frame and an aluminum frame based upon meeting an ultimate strength goal, the aluminum frame is much lighter than the steel frame. But this ignores...

Fatigue strength. You can plot the number of cycles of stress to failure vs applied cyclical stress. If you plot applied stress (vertical axis) vs number of cycles of stress to failure (horizontal, using a log scale) you start with ultimate stress (1 cycle), and see the log of the number of cycles increasing linearly as stress is lowered. At some level of stress, the number of cycles for some materials (such as steel and titanium) goes effectively to infinity. This is the fatigue limit. The fatigue limit for the steel below is 300MPa:

If the actual load applied to a steel frame of the type shown in the figure is always below 300MPa, the steel should effectively last forever. But stress is force divided by cross sectional area here, and as a previous poster noted, the high end bikes have a smaller cross section and hence get closer to the fatigue limit. Depending upon the rider weight, riding style, road or trail conditions, the fatigue limit may be exceed at some point in the frame (typically in areas of high stress, as the bottom bracket story above demonstrates).

So the point is, if you have an old Schwinn Varsity, weight 150, and only ride the bike on the retirement community paved bike path on your way to bridge and church, it will probably outlive several generations of your family. Thick tubing, low stress. A fancy-schmancy Italian job with ultra-lightweight tubes and shaved lugs and BB, ridden by a gorilla like me on rough streets, and there is a possibility of fatigue failure.

So, the question of infinite bike life is answered with a "no, not always, but maybe with your bike". I set up a lot of LeTours in the shop back in my youth, they appeared well-made, but not ultra-lightweight. Depending upon history, you may be able to ride that for a long time.

BTW, to ensure that the stress is kept low enough not to cause aluminum bike frames to fail, one needs to increase the tube thickness and weight to around that of steel (see Bicycle Science, 2nd or 3rd edition). But this added thickness has a benefit (or disadvantage, depending upon how you look at it): increased stiffness.

catgita

Your old steel bike probably has more life left in it today than a new carbon bike does off the showroom floor.

2manybikes

I have a steel Schwinn from 1951. It's fine. I was born in 1951, my frame is no where near as good as the bike.

I have a couple of steel bikes from the early 1970's. One is high end and not very heavy. They are fine. When the dog is in the 1973 steel trike, the loaded trike is about 110 lbs. Last week the computer I put on it when I got it passed 3,000 miles. There are plenty of antique bikes around, don't know how much they get ridden. I would say a well made steel frame can outlast you or me.

Rowan

I think there are a few high-wheelers/pennyfarthings kicking around that are pretty old and still going, too.

JohnDThompson 

I still commute to work on my 1972 Raleigh Superbe.

Wingsprint

I am confident the frame will outlive you.

spdracr39

Is that forever at 100 miles a year or 100,000 miles per year. Is it on flat smooth roads, in the mountains, on the gravel ? Yes in the house hanging on the wall the lifespan will be greatly increased, abused and raced weekly no.

GravelMN

All materials have their limits, but a good chrome-moly frame that is properly cared for will likely outlast the owner. It also has the advantage of being one of the most repairable materials.


Just for fun, I figured that out and it came to averaging about 17 mph, 16 hours per day, every day, for a year. Sounds like a 2016 goal to me

2manybikes

True. There is a club, around here. Lots of riders.

Mandeville

I have a 25 plus year-old steel MTB. I used to ride the heck out it. Still use it for errands around town. (I now use a RB for training and recreation.) Finally three years ago the frame broke near the rear axle. Paid 20 dollars to weld it which took 3 minutes. Then road the bike heavily for another year or so. Still riding like new.

SquidPuppet

It's going to let go very soon.

When cold setting even the highest quality tubing, you are sure to get about 17,030 - 17,050 miles. Right in that range is where they are all guaranteed to fall apart.

motorapido

That made me crack up laughing.

gregf83 

I phoned around quite a bit but couldn't find anyone to weld it. I thought of keeping it to ride on the trainer but in the end I think I put it out with the spring cleaning.

LesterOfPuppets

Yeah, probably don't wanna weld that. You'd wanna sweat all the tubes outta the BB shell. Replace the seattube and BB cluster. Braze it all up again, then repaint.

Would probably cost just shy of a complete brazed frame.

swampyankee

I used to do fatigue testing for a living (helicopter control system components). First, every material has a fatigue limit. Every single one. People talk about an endurance limit for low-carbon steels, and it may exist, but people also stop testing after a few billion cycles, and fatigue failures have happened way out there on the right end of the graph.

How long any bike frame lasts depends on a number of factors, including how it's ridden, how it's constructed, and pretty finicky details of materials: vacuum-melt steel tends to have much better fatigue properties than an otherwise identical part -- shape, composition, processing history. Fatigue life is probably going to be reduced by braze-ons (they're probably going to increase the stresses right around them). Corrosion will, of course, reduce fatigue life. What is really important is how much warning you have after the crack starts. Cracks can propagate very fast in some types of steel: those in the WW2 Liberty ships (google "liberty ship structural failure") moved at something like 15,000 ft/s. What you want is something that will obviously crack before failure.

Aluminum frames, which are typically welded, may have problems if the welding isn't of high quality.

AlmostTrick

Not sure why you made an exception for rust. While steel frames can and do rust, rusting to failure seems quite rare.

habilis

Forever is a long time. Look up entropy. Meanwhile, let's enjoy our old bikes. I'm riding a 1960s or 70s Raleigh frame that I cold-set twice (once to make it a 10-speed and years later to take a flip-flop wheel). The sensation in my hands told me that the frame is mild steel and can take quite a lot of this abuse. Try breaking a coat-hanger wire by bending it repeatedly. You'll be working at it for a long time - but not forever.