I love steel - I'm curious about the longevity of steel frames - particularly 1980's Italian (de rosa, colnago, etc)

How long can you ride and keep a steel frame before it starts to become unroadworthy.

GG

A steel frame has no "use by" date to it... It can be overloaded to the point of fatigue, but will usually show signs of it; cracks, bulges, etc. If inspected regularly, and taken care of, it will last a LONG time. I do have a steel frame damaged from being overloaded (not by me). This one was used as a fully loaded tourer by a heavy rider... and lasted for many years and many thousand miles before starting to crack behind the lower head lug. It was still being used by the previous owner, and he didn't even know it had a crack. I bought the frame from him, and he refunded my $$ when I convinced him the frame was no longer safe... I kept the fork, which still looks perfect (Reynolds 531/Campagnolo drops).

used to be called the "racer's paintjob"...get a new frame because this one is "getting soft". I know a little more about metallurgy nowadays; don't you believe it. If a steel frame "gets soft" it is because it has a crack in it somewhere. Steel has a good fatigue life, titanium too, except for chemically pure grade. Another matter entirely for aluminum, which has no practical fatigue life at all (something to reflect on next time you're watching the wings go up and down while you are flying on a 757).

A steel frame from the 1980s will be roadworthy for far longer than you will, so long as it is not mistreated! Regular riding will not fatigue the metal - with a steel frame, age of the steel is far less of a factor than hard use, and steel can take some pretty hard use!

luker, something else to reflect on is that the wings of a 757 (and any airliner) are fully intended to flex like that. This kind of fatigue is fully accounted for in determining the service life of an aircraft. "No practical fatigue life" is not at all an accurate statement when talking about aluminum, either in an aircraft or a bicycle. The difference between steel and aluminum is that aluminum has no fatique threshold, meaning that any stress at all, even from regular daily riding, will fatigue the metal. Steel, on the other hand, will not fatigue due to stress, up to a certain point. That doesn't mean that aluminum is prone to sudden and catastophic failure at any point - an aluminum bicycle or an aluminum aircraft will have a useable lifespan measured in decades, so long as they are not over-stressed... just like steel.

We took a 1900 mead,converted it to a motor bike(wizzer eng) and the crew was to build springer forks but didn't.So the bike was "driven"/road from san francisco to new york city.At bike speeds (5mph and under)28" roadster tires can take most of the road impact,but at speeds of 30+ the frame took all the pounding---lasted to the NY state line!

Just think; a bicycle from the 1980s could still be around in a thousand years if optimally kept... Long after our great grandkids have turned to dust, someone may wonder if that DeRosa can still be ridden... or maybe even question what the heck the thing is...

I have broken four steel frames, but two of them don't really count, because they had been straightened following front-end bend-back-the-head-tube collisions.

1960 Capo Modell Campagnolo (db Reynolds 531): front of downtube, just behind the butting, where it had been bent and restraightened;

1962 Bianchi Corsa (plain carbon steel): same;

1971 Nishiki Competition (db Ishiwata CrMo): seat tube lug broke off of top of BB shell;

1973 Peugeot UO-8 (plain carbon steel): right chainstay cracked between the tyre clearance and chainring clearance dimples

My other five steel frames (see signature) are still going strong.

sorry, you are absolutely right. Fatigue life and fatigue threshold are two different things, and I was being lazy (I have a technical document in peer review, so I should know better!). All that said, you must engineer an aluminum bike so that it doesn't flex or a failure will eventually occur. Cannondales and Kleins are two examples of such beasts. But I can watch the forks on my Vitus flex as I ride over bumps. Not much, probably not more than steel, but you know it has to be bending ever so slightly. Well, I ride it gingerly. and those long wings aren't flexing much either, but they are bending - aircraft are regularly inspected and removed from service when they reach their design life - but I still sit gingerly -

Anyway, something's gotta kill ya - and an airplane crash has the hidden blessing of being quick! (and kind of stylish - The Other Guy's great grandkids would talk about how he went out, I'll bet)

Fork or steering tube failure would indeed present a SERIOUS safety hazard, but I was never endangered by any of my four frame failures.