bikeworkshop
Senior Retro Guru
I'm sure there's loads of experience of frame failure amongst posters here. I've looked at hundreds over the years so I thought we could share our knowledge
I've seen plenty of beautiful 60s racers- paint in good condition, but holes in the stays rusting from the inside.
Early brazed mtbs too, lugged or brazed.
Its hard to wash out all the flux from brazing - that doesn't help.
Some framebuilders didn't do a good job, some didn't care as it won't matter for a decade.
Some craft builders weren't even aware of the problem
Sometimes the steel near the dropouts becomes granular with age - makes replacing the dropout a real challenge!
Early alloy frames are prone to fatigue - initially they were guaranteed for only 2 years!
Later alloys address this issue - as far as they can. I don't think it ever goes away though.
It's part of the reason alloy frame tubes got bigger and the bikes got stiffer.
A little used alloy frame will be much better than a well used one.
A cheaper frame would probably outlast a race- level model.
Titanium could last for ever... but rarely does.
The material shares qualities with both steel and alloy, leading to fatigue cracks along the tubes or through the joints (as opposed to across the tubes and along the joints)
I put this down to our lack of historical experience with ti.
Steel we know well.
Carbon ought to be stable, being a mesh of fibres set in epoxy - but some low quality epoxies weaken and crack, and many carbon frames aren't built to last anyway so occasional impacts can kill them quick.
My favourite carbon frame failure was a customer put his fancy summer bike in the shed over winter, and when he got it out in spring it had broken in two!
The dealer told him it was overexposure to heating/cooling cycles.
Love it.
And we all know of bonded frames coming unbonded. Often corrosion on the tube breaking the glue away, rather than the epoxy failing.
(Seen a few of them too, although if course people bring old bikes in to us because there's a problem, so I'm shown many more broken bikes than museum pieces
)
Brazed frame tubes can pull out of the lugs too if the brass didn't achieve good flow at the molecular level...see the flux issue above
I've seen plenty of beautiful 60s racers- paint in good condition, but holes in the stays rusting from the inside.
Early brazed mtbs too, lugged or brazed.
Its hard to wash out all the flux from brazing - that doesn't help.
Some framebuilders didn't do a good job, some didn't care as it won't matter for a decade.
Some craft builders weren't even aware of the problem
Sometimes the steel near the dropouts becomes granular with age - makes replacing the dropout a real challenge!
Early alloy frames are prone to fatigue - initially they were guaranteed for only 2 years!
Later alloys address this issue - as far as they can. I don't think it ever goes away though.
It's part of the reason alloy frame tubes got bigger and the bikes got stiffer.
A little used alloy frame will be much better than a well used one.
A cheaper frame would probably outlast a race- level model.
Titanium could last for ever... but rarely does.
The material shares qualities with both steel and alloy, leading to fatigue cracks along the tubes or through the joints (as opposed to across the tubes and along the joints)
I put this down to our lack of historical experience with ti.
Steel we know well.
Carbon ought to be stable, being a mesh of fibres set in epoxy - but some low quality epoxies weaken and crack, and many carbon frames aren't built to last anyway so occasional impacts can kill them quick.
My favourite carbon frame failure was a customer put his fancy summer bike in the shed over winter, and when he got it out in spring it had broken in two!
The dealer told him it was overexposure to heating/cooling cycles.
Love it.
And we all know of bonded frames coming unbonded. Often corrosion on the tube breaking the glue away, rather than the epoxy failing.
(Seen a few of them too, although if course people bring old bikes in to us because there's a problem, so I'm shown many more broken bikes than museum pieces
)Brazed frame tubes can pull out of the lugs too if the brass didn't achieve good flow at the molecular level...see the flux issue above
