Can someone help me with my question? Does titanium weaken with use and age? I am thinking about buying an older (mid-90's) used ti road frameset, but don't know whether or not to 'trust' the bike and therefore am seeking your advice. I am a bigger rider, 100kg or 220lbs, who will be using it for a long day (smooth) rides in very hilly terrain, and therefore will be forced to put down some good torque on the bb area etc and don't want it or anything else to fail..If it is a quality frameset from a reputable builder should this be a concern or is it 99-100% as strong as it was 15 years ago? Thanks.

I am no smitty nor am I trained in the art of metalurgy but I am going to say you should have nothing to worry about. I do not think Ti has a fatigue factor that something like a Aluminium bike would have

No.

No. But how is the frame constructed?

I can speak from personal experience that Ti bikes are very resilient. What frame are you looking at?

Like the man stated NO. Unless whe're talking about the welder screwing-up here so the answer as it pertains to the material is no on account of Titanium's fatigue rate is practically incalculable. They been tryin' to break it for years under thousands of tests, aircraft and otherwise. Even the Russian stuff is good.
The OP's referring to a mid-90s, to my knowlege very few "bad" frames were sold. I know of one and only one that's been disparaged, even that's questionable. Don't know the brand, can't vouch for the welder. Perhaps only the OP will state such.
One things for sure, Ti creates enormous controversy here at the forums.

Fellow here in Bham is still riding his 70'sTeledyne Titan. Sample size of one, I know.

No. Titanium does not fail like steel with long use. As long as any flex stays under the limit, it'll never fail. If it looks good, and sound, it's a fair bet all will be good with it forever with proper care.

They say quality Ti frames will last you a lifetime.

Be sure to test ride one before you buy it, as they are expensive, and 200+ lb riders sometimes find the ride too flexy.

What I meanis this: steel weakens with repeted flex over time( I think it's called modulus of elastisity). If you flex a paper clip over and over it'll eventually break, even if you don't flex it very much. Titanium though can be flexed up to a point without any damage, for ever. Stay under that flex amount, and it'll never fail. if the frame is straight, and has no noticable flaws, it's probably fine.

Thanks guys/gals.

I almost mentioned this but the post was for a mid '90s Ti bike and I thought someone else may bring it up. the only know issue with any Ti frame was the imfamous Teledyne Titan. but this was related to (as I understand it from what I have red) design issues dealing with the type of alloy and the crimping of the tubes to allow standard size clamps to be used.

I would still buy it if I came across one that was a good deal

Some of the Teledynes had a problem with cracking. I'd say if you got one from the 80's or later, it'll last longer than you will.

I think you are looking for the phrase "notch failure". This is only an issue with CP (commercially pure) titanium...failing along a stress riser. CP is made for chemical piping applications. Teledynes, and a lot of early titanium bikes, were made of CP. The builders realized the problem early and went to alloyed Titanium, like Ti-6AL-4V or 35AL-2V. These alloys are not prone to notch failure.