[Closed] Frame longevity - when do they become unsafe ?

It's a guide and not really a very good one at that.

Steel frames should go on indefinitely if well designed as should Ti

Aluminium is harder to quanify. After 5 years of regular riding, I'd be checking regularly for cracks but it could easily be ok for another 5+

And as for carbon, again, that just totally depends. In theory, if well treated then it could go on indefinitley.

if well treated then it could go on indefinitley.

which means literally "anyone's guess" :o)

exactly... I guess my point was that there isn't a definite lifetime in the way that there is with Aluminium which will snap through fatigue eventually (though it could be a long, long time...)

Isn't that new Meridia sub 1KG carbon frame guaranteed for 5 years for people who would need to be winched on to it?

no-one can give a guide on durability like that, there is no guide as tube wall thicknesses + diameters, fork used and rider style all need to be considered. just check the frame every 6 months or so.

mode of failure is more the issue - an old rusted or cracked steel frame will be more likely to go with enough warning to come to a controlled stop than a cracked alu frame.

When do they become unsafe?

About 100m before they fall apart!

no-one can give a guide on durability like that, there is no guide as tube wall thicknesses + diameters, fork used and rider style all need to be considered. just check the frame every 6 months or so.

Other variables to consider are the particular type of steel or aluminium used and its heat treatment, frame design etc etc...

I've a background in materials science (metals) and I agree with what james-o says, there are just too many variables to give prescriptive 'safe times' for frames - just check the frame for cracks and corrosion now & again.

A 10st. rider could have a bike and use it once a fortnight riding round local roads bridleways and towpaths
The same bike could be used by an 17st. rider jumping/dropping off of stuff and riding into everything going 3 times a week

Even as a rough guide a fixed period of time simply for a material is ridiculous. One could be a really thick walled beefed up frame and another a thin walled frame too

I had my 1998 Marin Pine Mountain frame resprayed last year - tis fine.

Anyone quoting even vague lifespans of frames based on materials is suffering from a serious case of "a little knowledge..."

There are just too many variables to take into account even in a general sense.

They are unsafe when they snap and you face plant the floor.

Im currently running an 2002 Foes Fly - DH bike which i ride 3/4 times a week and still hit big drops and jumps and a 2003 Zigzag HT that i dirt jump and ride 4X.

I'll stop using them when they crack.

I imagine road bikes take a bit less stress, but my Dad's steel road bike is still riding fine. I think he said the other day that it was 52 years old. He was riding it to commute every weekday for many of those years and it's still his main form of transport round town.

A horrible thing to ride mind, it has a super uncomfortable saddle, horrible pedals, 5 shonky gears, dodgy bottom bracket bearings and hasn't been oiled for years.

Joe

my maxlight xc pro after five years of thrashing... 9stone rider btw.

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no big jumps or anything, just hammered round trail centres and the like. Went all wobbly on me one day.

Kev

I have two old Ali bikes, a '93 Ridgeback & a '97 Zaskar, both have been raced Cyclo cross, cross country & down hill & haven't fallen to bits yet.
I ride with someone who has a '99 carbon hardtail (Giant) which still gets hammered & rode with someone at MM a couple of years ago who's Merlin Ti sanpped after 2 years.
Far too many variables to give any real life ages.