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Robbos
06-30-2016, 02:46 PM
Looking for some advice knowing very well it is hard to say with any real precision. But I'll ask none the less.
I've had my Cervelo Prodigy for over a decade now, and I've ridden it pretty regularly, with a very rough ball park of 20 000km on it (there are other bikes in my arsenal!). The paint job, which was never good to begin with is really starting to look rough. I've thought about repainting it, and maybe even getting my local builder to replace the head tube cable guides with down tube stops and maybe a new downtube. With the mileage I described, under 185 pounds of rider, one accident with a car (I took the brunt of the collision), and a downtube bottle mount that once got ever so slightly squished to the left), is it worth putting money into redoing the frame? I love the ride of this bike and I don't need or deserve better. I'm just nervous that investing roughly $200 to give it new life might be wasted if the thin Columbus Foco tubes (main triangle, don't know what the arse end is made of) decide they've had enough. Again, I know it is next to impossible to know when that might be, but feedback from the wizened council of forumites would be appreciated.

mg2ride
06-30-2016, 02:56 PM
That frame will likely last you forever.

sandyrs
06-30-2016, 02:57 PM
A decade is not enough time to kill a steel frame. See: the thousands of 70s and 80s steel bikes still on the road.

That said, if you're going to pay to get a new downtube welded on there, I'd consider getting a new frame instead and keeping the cervelo as a beater. Maybe keep the geo but go with a different tubeset because variety is the spice of life.

icepick_trotsky
06-30-2016, 03:18 PM
I think any bike you've put 20,000 km on is worth your $200 to keep it rolling. Even if it was a Schwinn Varsity.

upon3
06-30-2016, 03:27 PM
You know, back in the 90s there was always loose chatter that steel MTB frames had a finite life span. A number of miles on the clock that would turn the frame immediately into a useless pile of tubes. Not having teh internets or people around me that could set me straight, I sold the best bike I have ever owned with less than 6,000 trail miles on the odo. I felt like I needed to move it before it was worthless.

Serves me right for believing in it as I still am searching for that frame today. :crap:



Eventually, the Earth will reclaim everything, but steel bikes will most certainly outlast all of us if they are taken care of properly.

Robbos
06-30-2016, 03:29 PM
My other steel bikes with thicker tubes, well I wouldn't have asked the question. But Foco tubes are just so darned thin!

Mark McM
06-30-2016, 03:31 PM
Steel (or aluminum or titanium, for that matter) don't just suddenly "give up". The material can fatigue over time, but fatigue can be spotted before it gets to far. Fatigue is due to the slow growth of cracks, which start very, very small, and grow larger over usage/load cycles.

Inspect the frame carefully for the presence of cracks in the tube. Cracks tend to start in the areas of stress concentrations, such as joints and/or corners in the tubing. If there are no cracks present, then the frame should be good to go with no immediate worries. (If there is a crack present, it may be possible to repair - preferably sooner than later, before it grows any bigger).

icepick_trotsky
06-30-2016, 03:41 PM
The basics of steel as I understand it, and granted, I'm not a metallurgist, is that there's no such thing as cumulative fatigue or failure for steel.

In other words, steel has a stress threshold after which it will fail, but up to which it will not. Any amount of stress you put on the frame up to that threshold does not result in permanent damage. That is, it doesn't matter how many times you repeat those below threshold stresses -- you can repeat ad infinitum, and it will not cause failure. Repeated minor stresses don't stack or add up to major stresses.

Only stresses above the threshold result in permanent damage and eventual failure, like crashing it.

Mark McM
06-30-2016, 04:52 PM
The basics of steel as I understand it, and granted, I'm not a metallurgist, is that there's no such thing as cumulative fatigue or failure for steel.

In other words, steel has a stress threshold after which it will fail, but up to which it will not. Any amount of stress you put on the frame up to that threshold does not result in permanent damage. That is, it doesn't matter how many times you repeat those below threshold stresses -- you can repeat ad infinitum, and it will not cause failure. Repeated minor stresses don't stack or add up to major stresses.

Only stresses above the threshold result in permanent damage and eventual failure, like crashing it.

Mild carbon steel theoretically has what is called an endurance limit. The endurance limit is the threshold magnitude of cyclic stress below which the material will never fatigue.

However, bike frames are typically not made from mild carbon steel, but are made from high alloy steel, which does not have a true endurance limit. In addition, load cycles in actual use typically are a bit random, so there will still be occasional load above the theoretical endurance limit.

In the real world, all the metals used for bicycle construction (steel, aluminum, titanium) can suffer from fatigue.

unterhausen
06-30-2016, 04:52 PM
if you don't let rust kill it, a steel frame will probably last forever. That is, absent any construction flaws. The Italian racing frame I bought in the early '80s lasted me until about 5 years ago. I developed an irrational fear that I had let it rust too much.

Having said that, there are plenty of fatigue failures on steel frames. It's best to monitor for them and also use something like framesaver to combat internal rusting

johnniecakes
06-30-2016, 08:00 PM
Not an answer but an option. I have been searching for a prodigy for a long time. IF you decide to retire it let me know. As an opinion I rode my Bill Boston for 20 years till a collision bent the front end more than I wanted to repaƬr. The Cora Extra still sees regular duty.

Tandem Rider
06-30-2016, 08:12 PM
I would just watch the rust and ride the snot out of it. I have yet to see or experience a catastrophic crash inducing failure on a steel frame, and I've broken a bunch of them.

Louis
06-30-2016, 08:13 PM
What some folks are talking about above is the shape of a given material's S-N curve. S = stress, N = cycles to failure.

Basically the S-N curve for most steels tends to flatten out at high cycles, so at stresses below that it can take an infinite amount of cycles. That's called the "endurance limit" of the material.

For AL the curve doesn't flatten out, so if you get enough cycles at some stress level it will fail.

However, more important than whether or not there is an endurance limit is level of the stress itself. Given a high enough stress (due to say, a crash, bad design, or bad manufacturing) anything will fail.

As has been pointed out many times, there are plenty of AL aircraft flying around, some of them quite old.

http://www.efunda.com/formulae/solid_mechanics/fatigue/images/fatigue_SN_01.gif

rustychisel
06-30-2016, 08:15 PM
if you don't let rust kill it, a steel frame will probably last forever. That is, absent any construction flaws. The Italian racing frame I bought in the early '80s lasted me until about 5 years ago. I developed an irrational fear that I had let it rust too much.

Having said that, there are plenty of fatigue failures on steel frames. It's best to monitor for them and also use something like framesaver to combat internal rusting

This. Rust will be the killer, and I think you've had it long enough to rule out obvious construction flaws.

My main riding bike is Reynolds 531db and was made in 1964. That's right, 52 years ago. A race bike for a decade, then a ride to work beater for about 25 years, then after I'd had her for a few years (2nd owner) I had her totally refurbished and fully rebuilt - fixed gear. The ride is sublime and I'm confident she'll be with me until the end.

Llewellyn
07-01-2016, 12:42 AM
My main riding bike is Reynolds 531db and was made in 1964. That's right, 52 years ago. A race bike for a decade, then a ride to work beater for about 25 years, then after I'd had her for a few years (2nd owner) I had her totally refurbished and fully rebuilt - fixed gear. The ride is sublime and I'm confident she'll be with me until the end.

Would love to see a pic.

Peter B
07-01-2016, 01:04 AM
The frame will likely outlast you unless you let rust get the best of it. If you know of a reputable builder who will braze cable stops, replace the DT and paint for $200 I'd say go for it. My guess is you'll be hard pressed to repaint only for that price. Basic powdercoat is more likely. Bottle braze-ons can usually be repaired w/ Rivnuts. Not sure I'd bother with the major metalwork on that bike. Put your money towards some sort of replacement or bank it instead.

dgauthier
07-01-2016, 03:01 AM
I seem to recall reading that a steel bicycle frame (that is not raced or rusted) has a lifetime of about 70,000 miles. I do realize that is a sweeping generalization...

rustychisel
07-01-2016, 04:18 AM
Would love to see a pic.

Don't have any at the mo due to computer death, backup files being somewhere else, that kinda thing. Will find. :beer:

soulspinner
07-01-2016, 06:40 AM
My other steel bikes with thicker tubes, well I wouldn't have asked the question. But Foco tubes are just so darned thin!

Have a Strong foco built in 2003 with about 35000 miles on it. Its been refinished by Carl a long time ago and remains a keeper. Frame before that was a custom foco with lotsa miles and my neighbor is racing it in the Wed nite worlds around here so his S series Cervelo doesn't get wrecked. Clean and check it once in a while but don't be afraid of it. :beer:

Black Dog
07-01-2016, 08:40 AM
I seem to recall reading that a steel bicycle frame (that is not raced or rusted) has a lifetime of about 70,000 miles. I do realize that is a sweeping generalization...

Some one writing it does not make it factual. Steel has a lifespan that is determine not by miles alone. That lifespan can exceeded 70,000 miles by an order of magnitude or fall short of 7000 miles.

El Chaba
07-01-2016, 09:09 AM
The definitive answer:
It all depends....

srice
07-01-2016, 09:17 AM
I decided to move on from steel frames this year. I used to believe that a quality steel frame had a very long life if rust was kept at bay. I no longer believe that. After suffering 2 broken forks and a cracked head tube in about 70,000 miles on a single high end steel bike, I have decided to move on from "trophy bikes" to more utilitarian bikes that fit me well and are comfortable for the number of miles that I ride. If you want to keep a "trophy", that's great but don't plan on it lasting a long time if you ride it a lot.

martl
07-01-2016, 09:19 AM
Steel (or aluminum or titanium, for that matter) don't just suddenly "give up". The material can fatigue over time, but fatigue can be spotted before it gets to far. Fatigue is due to the slow growth of cracks, which start very, very small, and grow larger over usage/load cycles.

Erm.... no. As Louis pointed out, Aluminum behaves fundamentally different than steel for fatigue. The bit about those "micro cracks" is a myth.

AngryScientist
07-01-2016, 09:21 AM
as has been gone over above, there is no way to make any generalizations about the lifespan of steel bicycles, as there are simply too many variables to isolate a conclusion of any sort.

i say that if you like the bike, check it thoroughly in all the high stress areas for cracking, and if you find none, have it re-sprayed and ride it happily.

Joxster
07-01-2016, 09:25 AM
My 1988 Daccordi was a race bike for a season (circa 10,000 miles) then became my training bike for a season (roughly 500 miles a week) then became winter bike with mudguards for about 10yrs before becoming a fixed hack bike till 2010 and it's still going strong :beer:

weisan
07-01-2016, 10:08 AM
If only people can be as trustworthy, loyal and dependable as old steel bikes....

bobswire
07-01-2016, 10:29 AM
Those are really really nice frames and if not rusted would be worthy of repair/new paint. I owned one, light agile frames but like you said the paint
on them was not the best.

I have a Jeff Richman late 70's or early 80's frame that was in need of repair and new paint which I had done by Allan Wanta in March 2013 and I'm still riding that bike today. It is a special frame to me and well worth the upgrade.

> http://forums.thepaceline.net/showthread.php?t=126552

In its current configuration.

http://i63.tinypic.com/35a7vco.jpg

Mark McM
07-01-2016, 11:08 AM
Erm.... no. As Louis pointed out, Aluminum behaves fundamentally different than steel for fatigue. The bit about those "micro cracks" is a myth.

You should probably check your facts before trying to correct someone.

Several modern research studies like this (http://onlinelibrary.wiley.com/doi/10.1046/j.1460-2695.1999.00183.x/abstract) one show that in fact, there is no such thing as an infinite fatigue life in metals (i.e., even steel doesn't have an endurance limit).

Even when it was thought that steel might be an endurance limit, practical engineering found that you couldn't rely on the endurance limit in real-world situations (http://www.epi-eng.com/mechanical_engineering_basics/fatigue_in_metals.htm):

Unfortunate experience has taught engineers that the value of the Endurance Limit found in laboratory tests of polished, optimized samples does not really apply to real-world components.

And yes, metal fatigue (https://en.wikipedia.org/wiki/Fatigue_(material)) really is the initiation and grown of cracks (which start out at the microscopic level):

Fatigue occurs when a material is subjected to repeated loading and unloading. If the loads are above a certain threshold, microscopic cracks will begin to form at the stress concentrators such as the surface, persistent slip bands (PSBs), and grain interfaces.[1]

MattTuck
07-01-2016, 11:13 AM
Steel frames go dead after 5-10 years. It is indisputable. Please send to me for proper decommissioning.

MikeD
07-01-2016, 11:14 AM
Plenty of steel frames fail at stress risers, making this discussion of endurance limit moot. The most reliable frames of any material are the ones that have been made for a number of years so the problems that cause early failures have been worked out. I remember when Trek used to sell bonded Aluminum road bikes. The Trek rep told me that they had the least warranty claims of all the bikes they sold at the time.

Joxster
07-01-2016, 11:36 AM
1697922487

My old steel hack :)

martl
07-01-2016, 02:19 PM
You should probably check your facts before trying to correct someone.

Several modern research studies like this (http://onlinelibrary.wiley.com/doi/10.1046/j.1460-2695.1999.00183.x/abstract) one show that in fact, there is no such thing as an infinite fatigue life in metals (i.e., even steel doesn't have an endurance limit).

Even when it was thought that steel might be an endurance limit, practical engineering found that you couldn't rely on the endurance limit in real-world situations (http://www.epi-eng.com/mechanical_engineering_basics/fatigue_in_metals.htm):



And yes, metal fatigue (https://en.wikipedia.org/wiki/Fatigue_(material)) really is the initiation and grown of cracks (which start out at the microscopic level):

Every single failure (=crack without prior accident) of a steel bicycle frame in the history of the vehicle was either because of bad design (couldn't handle the stress), a load it wasn't designed for, or because of a manufacturing failure (mostly overheating of the tubing material thru faulty frazing or welding causing the material to lose its strength. A well designed and built steel bicycle frame is as strong at 120.000km ridden as it was when new. I have owned and do own a couple of very well-ridden samples in my garage to provide anecdotial evidence, like a Kessels-Merckx that possibly has been battered around countless Kermesses by a big guy and still rides as rock-solid as they come. Or an "Altinger" RH64 made from SLX/TSX ridden by a guy of 6Ft4 and 185lbs for documented 100.000km+. And I have never heard a story of an aged bicyle frame that cracked while under no higher load than usual that would hold up to fact check.
That is all the fact i need to know.

cheers,
Martl, Dipl-Ing (FH) Fahrzeugtechnik

Bob Ross
07-01-2016, 03:30 PM
And yes, metal fatigue (https://en.wikipedia.org/wiki/Fatigue_(material)) really is the initiation and grown of cracks (which start out at the microscopic level):

Damn, I was certain your embedded link was going to point to this (https://www.youtube.com/watch?v=g_TxIBJ7T0M)!

bigbill
07-01-2016, 03:50 PM
I've got steel GTs from 93 and 97, a MX Leader from 99, and a Big Leg Emma from 2006. I expect each to outlast me. If I bought a new BLE, it would look just like the one I've got.

ColonelJLloyd
07-01-2016, 03:53 PM
I ride a Jack Taylor from the late 40s or early 50s. The BB shell was replaced some time in the early 50s for some reason. I see no reason it can't be ridden for several more decades.

Mark McM
07-01-2016, 04:31 PM
Every single failure (=crack without prior accident) of a steel bicycle frame in the history of the vehicle was either because of bad design (couldn't handle the stress), a load it wasn't designed for, or because of a manufacturing failure (mostly overheating of the tubing material thru faulty frazing or welding causing the material to lose its strength. A well designed and built steel bicycle frame is as strong at 120.000km ridden as it was when new. I have owned and do own a couple of very well-ridden samples in my garage to provide anecdotial evidence, like a Kessels-Merckx that possibly has been battered around countless Kermesses by a big guy and still rides as rock-solid as they come. Or an "Altinger" RH64 made from SLX/TSX ridden by a guy of 6Ft4 and 185lbs for documented 100.000km+. And I have never heard a story of an aged bicyle frame that cracked while under no higher load than usual that would hold up to fact check.
That is all the fact i need to know.

Nice back-pedaling. First, you say steel won't fatigue, and now you say that it can, but only due to design/construction/usage errors. But that's also not necessarily the case.

Example: The Ritchey P-21 was an ultra-lightweight steel MTB racing bike from the early '90s. It was made from very thin walled tubing and low weight was its primary objective. It was sold with no warranty, and was only expected to last about 1 season of racing. Many of them broke - but if it took more than a year or so to break, then it did exactly what it was designed to do.

John H.
07-01-2016, 04:44 PM
I'd continue to ride it- I'd even hang new parts on it as stuff wears out.
But I wouldn't put any money into the frame- when it is done, move on and get something else.
They were nice riding frames but not super in terms of finish or workmanship- you can buy a nice used steel frame for not much more than repair or refinish would cost.