My crack

[Venod]

A replacement frame is the way to go if under warranty but a cracked frame isn't always a write off, @davidphilips offers some good advice up the thread, I had a very thin Titanium frame repaired because of a crack and rode it for a year before selling it.

 

[SkipdiverJohn]

Dropped seat stays are to try and improve comfort, by ‘disrupting the transmitted shock’s pathway’ they do have a tendency to fail at that point though.

A classic case of poor engineering practice, which seems the norm on a lot of modern bikes. Having stupidly long seatposts sticking out of undersized frames is another example.

 

[Racing roadkill]

A classic case of poor engineering practice, which seems the norm on a lot of modern bikes. Having stupidly long seatposts sticking out of undersized frames is another example.

Very true.

 

[Cycleops]

A classic case of poor engineering practice, which seems the norm on a lot of modern bikes. Having stupidly long seatposts sticking out of undersized frames is another example.

You missed out the wisdom of using aluminium at all in such a configuration.

 

[Drago]

And seatstays terminating down the seat tube instead of level with the crossbar. Looks trendy, creates a massive fulcrum point for the seat tube to flex around.

 

[Vapin' Joe]

And seatstays terminating down the seat tube instead of level with the crossbar. Looks trendy, creates a massive fulcrum point for the seat tube to flex around.

And all in the cause of some dubious bollocks about comfort or stiffness, or whatever the latest fad is.

 

[bpsmith]

Nothing wrong with any of those designs, they just have to weld it properly.

 

[Drago]

Its not the weld that has cracked.

 

[Tim Hall]

Never mind all that, can you sort your rear brake cable out please? The way it enters the adjuster is making me itch.

 

[I like Skol]

Never mind all that, can you sort your rear brake cable out please? The way it enters the adjuster is making me itch.

I was going to say that this morning but didn't want to kick a man while he was down......

 

[Gravity Aided]

Its not the weld that has cracked.

But it's not the prettiest weld I've seen, either. It looks pretty inconsistent.

 

[bpsmith]

Its not the weld that has cracked.

Looking at it again, you’re right, of course. Actually, if anything, the weld is in pretty good shape and clearly the tube has cracked above the strong weld. First look suggested otherwise, which is my mistake.

EDIT: Looking a third time, is it the tube cracked or the top of the weld between tube and weld?

So are we all thinking the design is what caused this?

 

[Drago]

Possibly, but I guess we don't really know.

 

[3narf]

You missed out the wisdom of using aluminium at all in such a configuration.

I would tend to agree. It's all very well designing in some flex, but aluminium has a finite fatigue life and Chinese factories only have quality control if a customer rep is watching.

 

[Venod]

Looking at it again, you’re right, of course. Actually, if anything, the weld is in pretty good shape

The weld looks fine but sometimes the Heat Affected Zone (HAZ) of a weld is compromised by mistakes when welding.

http://weldinganswers.com/why-welds-crack/