dugay

i bought a bike then saw this when i took out seatpost wot can i do to fix this plz

oops
plz

Geepig

Oops indeed...

Is it steel or some other metal?

One of the options is to grind, a bit brutal, might be to grind away the whole clamping part to recreate a traditional tube + separate clamp situation.

dugay

its alloy i like that idea don't see any other choice really

alo

I agree. Grind off the existing clamp, and use a clamp over it.

Amt0571

If there's enough tube, i'd just cut it just below the clamp and attach a separate clamp.

freeranger

Agree with Geepig. I also have a GT with integrated clamp. Older chro-mo frame. Hoping that never happens. Seems like an integrated clamp with "ears" are a bad idea-would much rather have a seperate clamp around the post. Hope all works out for ya!

'02 nrs

if not enough metal for a clamp after trimming you can do a quill type post.American Classic,Suntour,Campy made them at 1 time.



https://www.bicycles.net.au/forums/v...ic.php?t=98366

Litespud

I agree with the others - remove the ears and use a separate seat post clamp. I wouldn't cut off the top of the tube, regardless of your available seat post length. You may end up having to extend the slot to give the seat tube enough "flex" to clamp the seat post, but then you'd be getting a bit close to the welding at the top tube junction. In your situation, I would also use a small hacksaw or Dremel cut-off wheel to remove the bulk of the ears before carefully using the Dremel or a hand file to finish the job. Alloy is relatively soft - a full-size grinder will go through it like butter if you're not careful. You want to preserve as much of the original tube material as possible.

Cyclist0108

I would skip the grinding and just try that first. That is a great idea. I never knew such a thing existed. Where do you put the Di2 battery?

Edit: Maybe it doesn't? Dead link.

dugay

Thanks guys hack saw then hand filed it and fit was perfect for a 31.8 clamp

JoeTBM 

Nice job, should work well

sweeks

This might work. The only problem I foresee is that the slot in the rear of the seat tube might be too short to include an adequate stress breaker (the hole at the bottom of the slot).

Just saw the picture. I would enlarge the base of the slot to a diameter at least twice as wide as the slot. It won't affect the strength of the tube, or the retentiveness of the clamp. If you don't do this, be sure to check regularly for cracks branching off from the bottom of the slot. If you catch it in time, you can then enlarge the bottom of the slot to include the crack. See the attached before and after images of one of my bikes' seat tube.
The good news is that if the fracture eventually circumnavigates the seat tube, you won't have a catastrophic event. The seat will just pull out if you lift the bike by the saddle. It'll probably oscillate a bit when you ride as well.

Also attached is an image of my "winter" bike. There's a pretty obvious separation of the top part of the seat tube. It's held in place by home-made stays, and has been like this for over half of the bike's 13,000 mile life. I wish I had modified the stress-breaker in a timely fashion.

One more comment: My bikes are folders, and the seatpost clamps are cycled at least four times a day. So they're going to rack up cyclic fatigue a lot faster than you will on a seat that's rarely adjusted. Still a good idea to keep an eye on it!


The stress-breaker at the bottom of the slot has a radius that's too small. This will eventually separate the top of the seat tube from the lower part.



Here's the result of enlarging the stress-breaker with a Dremel tool. It's paints to match the frame and has survived over 1,000 miles with no further cracking.




The seat tube has fractured 360 degrees, starting with cracks at the (too small) stress-breaker. There is no danger from this, but it looks like crap!

Amt0571

The slot should be enlarged with a drill and a file if he cuts the tube.

BTW, my Dahon had the same issue as yours. I also enlarged the hole and made a drill stop on one of the cracks that was further away. Had no more issues so far.

sweeks

A drill would work well. A Dremel tool also works, and allows a measure of "chamfering" of the edges.
I have crack-stop holes in several places on another Dahon (Helios XL). Also, see the attached!


Crack-stop holes on the handlepost of my Dahon Mu XL. No progression for several years.

Amt0571

I was sure Dahon have serious issues with their warranty (mine cracked with 2500km ridden, and they didn't honor their "lifetime warranty"). Now I also know they have serious issues in how they make frames and components.

I bought my Dahon because I needed a folding bike with wide gearing range at a non-prohibitive price (mine has a DualDrive), but now I only keep it because I barely use it. If I needed an everyday folding bike as I did when I bought it, I wouldn't buy one again.

Not sure what I would use though... I tried a Brompton S6L long time ago and I could put up with the gearing and overall flex, but stability when going +50kph was crap.

makshima

Pardon my ignorance, but don't Dahon's have lifetime warranty on their frames?

veganbikes

A simple search on the googles brought this up:

DAHON Limited Warranty (excluding China)

We warrant our bicycle frames, handle posts and rigid forks to be free of defects in materials and workmanship for a period of 5 years. In addition we warrant all non-wear components for a period of 2 years. Certain individual component warranties and local law may supersede this warranty policy.

This warranty is limited to the repair or replacement of a defective frame, handlepost, fork or component, and is the sole remedy of the warranty. This warranty applies to the original retail purchaser of the bicycle and is non-transferable. This warranty only covers DAHON bicycles sold through authorized DAHON resellers, and maintained per the Scheduled Maintenance explained above. Any replacement item is covered by the original warranty term, being from the purchase date of the complete bicycle.

Your warranty does not cover normal wear and tear, abuse, stunt riding, commercial use, improper assembly or maintenance, installation of parts or accessories not originally intended or compatible, installation of power systems such as engines or electric motors, damage due to accident, weather or neglect, or modification of the bicycle.

A defect in material or workmanship is defined as; “A flaw, failure or cosmetic blemish caused by the manufacturing process or material that was not consistent with the original design”. This warranty implies no strength or fatigue value beyond regional government standards. This warranty does not mean “indestructible” as all materials can fail if pushed beyond design and manufacturing limits.

Wear items are defined as; tires, tubes, brake pads, brake and gear cables and housing, chains, gears, grips, and saddles. All of these items are subject to varying wear life depending on use, load, weather, road conditions etc. Premature wear or “defect” will be taken into account in any claim involving a wear item.

Exclusions

All damage resulting from Commercial use, accident, misuse, abuse, neglect, improper maintenance, or from anything other than normal and ordinary use of the bicycle.

All damage resulting from off-road or stunt riding, multiple passengers, or cargo hauling.

Any paint damage, rust, or modifications made to the bicycle.

DAHON bicycles sold in mainland China fall under a separate policy which is non-transferable outside of mainland China.