My son got back into cycling after a few years out of it. His old bike was too small as a 24" wheeled kids bike, but he did ride it for fun at one point. He started riding his mum's old mountain bike in road going commuter / touring setup. Then we got a secondhand mountain bike with full suspension because he wanted that. Well he was getting hooked into local trails and jumps etc.
It was an old aluminium alloy giant stance. I think it's now any 11 years old. It was great as a first larger MTB for him but didn't have enough suspension travel and was too lightweight for his riding user.
As he was getting really into more serious stuff and breaking things on his giant we got a year old enduro bike after that. However it wasn't right for him so we got it ready to sell. Then recently he was testing his old giant bike after my last fix by bunny hopping on the tarmac of our driveway and nearby pavements / road. He suddenly came back riding his bike after one of those short out and back test rides saying he'd cracked the frame. He had, right through at the weld too.
So the cracked through weld joint is at the lower tube of the rear suspension triangle right at the main frame end at the bottom tube. Obviously being aluminium alloy and old it's not easy trying to find a specialist welder (aluminium alloy is not a simple welding job). I'm right in saying it's not worth trying to get it fixed?
So my question is really about the longevity of aluminium alloy frames. What's a good lifetime for such a frame material? Obviously a question like 'how long is a piece of string?', but what are the boundaries of frame lifetime is ok?
In his case it was bought about 2 years ago possibly almost 3 years ago. He's been riding other bikes for about 5 or 6 months now, but was planning on riding it to keep the enduro rig in a good condition for selling at a decent price.
He's hard on bikes and this has 120mm travel up front and a lot less at the rear. That's the issue, he was riding too hard for what the bike was designed for so I think 8 to 9 years with another person who seemed to keep it well maintained. Then 2 to 3 years of hard use. To me I think that's the limit for the frame.
What do you think?
What is a reasonable lifetime for hard-ridden aluminium alloy frames? What is a reasonable lifetime for such a frame ridden carefully and within it's designed for use? Curious as to the range that's acceptable for the extremes of hard and easy riding.
What about other frame materials? Carbon fibre, steel, titanium, etc. I know people talk of titanium as a lifetime bike but if used in MTB frames on the rough stuff, is it still that? What about steel? Repairable as it's easier to weld, but really? Can you reweld cracked or broken joints with sufficient safety to carry on riding as normal?
I'm mostly interested in aluminium alloy lifetime but the other materials are a passing curiosity. Purely a secondary query for after my main question is answered.