My bike broke in half......

[simon the viking]

I can't believe that people are suggesting mending this with gaffa tape or superglue! Its a weld gone! Wheres the safety factor! It would break again as soon as he sat on it..

Everyone knows for a break like this cable ties and a wooden stick are the answer... sheesh... bodgers

 

[12boy]

Frank, I presume you have read Sheldon Brown on Raleigh 20s? Bitchin rides in there.

 

[FrankCrank]

Frank, I presume you have read Sheldon Brown on Raleigh 20s? Bitchin rides in there.

....yeah, no worries, I'm a fan of them now for sure. Twenties were Raleigh's best selling bike, there must be so many languishing in the back of garages looking sorry for themselves. It is 2020 after all, so dust off that Twenty and give it a new lease of life - definitely deserves it

 

[doginabag]

If it is going to fail, it's not an unexpected place for it to happen. When aluminium is welded, it's limit stress reduces to around 50%, depending on the grade.

when you stick a hinge int he middle of a the frame where the bending stresses are at their highest, you will end up needing a tube sizes twice the size of what you would need if the frames was continuous without any welded joints to compensate.

 

[12boy]

Here is my Al folder, a Xootr Swift. It's frame is fairly stout and the seat post, which holds it together is fairly thick. Earlier Al Swifts had breaks where the chainstays crossed the seat post and later ones such as mine, have beefier ones. Note the gusset below the head tube/top tube.
This is a very rigid little bike, although the wheelbase is actually the same as many hybrids.
area.

 

[Schwinnsta]

If it is going to fail, it's not an unexpected place for it to happen. When aluminium is welded, it's limit stress reduces to around 50%, depending on the grade.

when you stick a hinge int he middle of a the frame where the bending stresses are at their highest, you will end up needing a tube sizes twice the size of what you would need if the frames was continuous without any welded joints to compensate.

I think it likely that the heat treat takes place after the welding.

 

[doginabag]

I think it likely that the heat treat takes place after the welding.

It's possible, and maybe more likely in a high end product, but in my experience it's not the norm.

It isn't an issue as long as it is considered during the design, but if there is going to be a failure, the heat affected zone is where you would expect a failure to occur.

Some info and strength tables here, I would expects most bikes are made from a 6xxx grade.
https://www.esabna.com/us/en/education/blog/the-haz-in-aluminum-welds.cfm

 

[confusedcyclist]

I wouldn't buy an aluminium frame again.

The only two alu bikes I've had - both the frames cracked.

Luckily neither was a complete through-and-through like that.

Glad you're OK.

You might be disappointed to hear this, but all frame materials fail... eventually.

 

[Kell]

You might be disappointed to hear this, but all frame materials fail... eventually.

Of course, but as said, with steel it's never quite as dramatic and is often repairable.

Of those bikes, one had been ridden for less than 4 years, the other for less than a year. I don't really see that as acceptable.

The only caveat is that I found out later (i.e. after both bikes had cracked) that the rider weight limit was 95kg. Which is/was my weight almost to the gram.

 

[confusedcyclist]

Aluminium, if constructed correctly should give many years of service, rider weight not being pushed to the limits of course

I agree though, I personally opt for steel as I'm not a weight weeny, and durability and repairability are important factors in my choices, and I'm no feather weight either.

 

[Drzdave58]

I have had many aluminum and steel frame bikes...I much prefer how my steel frame bikes ride...way more comfortable imo...

 

[Smudge]

In aluminium framed bikes and steel framed bikes, both can fail if they are poor quality. I just dont buy that reasonable quality alu framed bikes will break easily, many alu bikes have been around for a long time. I've never had one one break on me, or fracture at the welds yet and i'm not exactly a lightweight rider.

 

[FrankCrank]

Back on hols in Koh Chang, where my folder snapped in two. This time with my trusty R20, a '77 vintage, and wouldn't be surprised if it kept going for another few decades.........

 

[the_mikey]

What makes you think its a rebadged Dahon ?
I've never seen a Dahon with a frame like that, or a Tern come to that. I know Tern had a spate of their folders breaking at the main hinge, but this was after they parted from Dahon.

I owned a Tern from 2011 that was subject to a recall, (2013) the weld on the hinge part was suspected and I had the frame replaced free of charge as part of the recall.

 

[Smudge]

I owned a Tern from 2011 that was subject to a recall, (2013) the weld on the hinge part was suspected and I had the frame replaced free of charge as part of the recall.

Good that they did a recall. I guess they didn't want to be stuck with the reputation of frames breaking. Although i expect it cost them a lot of sales around that time.
Have you still got the folder ?