Snapped main frame - Dawes ladies bike

[Crankarm]

Whilst I was in Ben Haywards in Cambridge today an old guy came in with a silver Dawes bike which I thought was a folder until he said to the sales chap it had literally snapped in half . I was tempted to get a quick pic but the other grumpy sales woman would have become even more grumpy.

It was bizarre. The main frame had snapped clean in half just about by the position G of the word Geneva although I couldn't be sure it was a Geneva model but this is where the break was. The guy who brought it in said it was his wife's bike (no cross bar) and the break may have started as a small fatigue crack which he pointed to. Anyway the sales guy said they would strip the bike down and send it back to Dawes under warranty. I was more concerned whether the wifey was ok as he said the failure had been sudden and obviously totally unexpected. Hubby said she had been very shaken up hitting the deck quite hard hurting her shoulder but she would be ok ! The ali frame tubing looked really thin couldn't have even have been 0.5mm thick. Looked just like egg shell.

I think it was one of these Dawes ladies bikes,

http://www.dawescycles.com/p-259-geneva-ladies.aspx

so if you or your wifey has one or similar check the main frame for any sign of fatigue cracks.

 

[Hilldodger]

That's pretty unusual and that frame is pretty generic to lots of brands. Hope it was just a bad one.

 

[RecordAceFromNew]

As the people from Rivendell never stop saying, aluminium and carbon are intrinsically inappropriate materials for safety critical bike components due to their crack/fatique characteristics and catastrophic failure modes... I admit I use them too, but I do worry. What gives me nightmares is this

http://2.bp.blogspot.com/_V54WWNeyy...QG6Zxln-0/s1600-h/2969039343_b70ce17c1d_b.jpg

from

http://www.bustedcarbon.com/2008_10_01_archive.html

 

[Davidc]

Reinforces my existing prejudice against aluminium for bike frames.

That said one of my bikes does have an ali frame and I do worry a bit about it failing. I'm not even sure what the visible symptoms are before aluminium fails catastrophically.

 

[tyred]

My understanding is that aluminium (and carbon) will fail suddenly and without warning whereas if a steel frame is to fail, it will probably slowly develop stress cracks long before it goes completely so you will hopefully notice when cleaning or servicing.

 

[Davidc]

My understanding is that aluminium (and carbon) will fail suddenly and without warning .

So presumably there's no way of predicting that the bike's going to collapse under you?

If that's the case what's the typical safe working life miles/years for a frame in those materials?

 

[raindog]

My God, this is scary stuff. I was talking to a pal about this a couple of days ago, and we both have carbon seat posts but agreed we would never use carbon stems and bars. But it looks as if even ali can fail suddenly too. But surely a failure such as the op is very, very rare?

 

[GrasB]

The thing is how many of those failures were accident related? Well most of them & from experience a CroMo frame may not stand up any better.

 

[Crankarm]

The thing is how many of those failures were accident related? Well most of them & from experience a CroMo frame may not stand up any better.

This one didn't appear to be. I couldn't see any sign of damage around the break or the frame. Frightening apparently the main tube broke without warning.

Aluminium, the right grade and thickness, structural design is pretty strong. Aluminium is use widely in aircraft construction.

I would never have a carbon seat post, stem or forks. I have heard of too many snapping. Probably wouldn't have carbon handle bars either. Ali T6061 or 7005 for me or steel for fork and frame.

 

[Tynan]

all materials, well nearly all, are safe for aything as long as you use enough of it properly

all that shaving weight and material is the problem

 

[GrasB]

Crankarm, I wasn't referring to the case you saw more the site with all the broken carbon. I also think that there's a breed of person who will see a crack in a frame, handle bar, seat post, etc & instead of being sensible & replacing it goes something like "oh it's fine for now" & rides on

I'm also with Tynan on material safety, with this current obsession (with both riders & thus bike manufactures) with removing every last gram of 'excess' weight frames become less resilient.

 

[Arch]

A friend of a friend of mine came across a chap sitting by the road with a Boardman that had snapped clean in half. I can't remember the material, but it shows, it happens...

 

[Crankarm]

Crankarm, I wasn't referring to the case you saw more the site with all the broken carbon. I also think that there's a breed of person who will see a crack in a frame, handle bar, seat post, etc & instead of being sensible & replacing it goes something like "oh it's fine for now" & rides on

I'm also with Tynan on material safety, with this current obsession (with both riders & thus bike manufactures) with removing every last gram of 'excess' weight frames become less resilient.

F1 cars would quickly fail if driven on normal roads, plus would be undrivable. Like wise for top end race bikes that have every last 0.1 gramme shaved from their weight. Whether car or bicycle the whole marketing of products is aimed at faster and lighter. But keeping cost low is invariably the hidden excuse. Hence bikes frames, stems handle bars etc when they break you see that they are frigteningly thin.

 

[Crankarm]

A friend of a friend of mine came across a chap sitting by the road with a Boardman that had snapped clean in half. I can't remember the material, but it shows, it happens...

A half-board man .

 

[Crankarm]

Crankarm, I wasn't referring to the case you saw more the site with all the broken carbon. I also think that there's a breed of person who will see a crack in a frame, handle bar, seat post, etc & instead of being sensible & replacing it goes something like "oh it's fine for now" & rides on

I'm also with Tynan on material safety, with this current obsession (with both riders & thus bike manufactures) with removing every last gram of 'excess' weight frames become less resilient.

Candidates for a Darwin Award .........