Deda SuperCarbon and their patented semispherical head bolt

holybinch

Hi guys,

on the Grand Fondo Luciano last Sunday, 3 miles from the end, the bolt from the saddle clamp of my seat post, a Deda Super Carbon, snapped in 2 halves.
I have to say it was a pretty scary thing, but I survived, and now I have to fix the mess.
The bolt snapped very nicely, in halves, like it had been cut (must think of interrogating the gf, you never know...)

Anyway, now I'm looking for a replacement bolt, and can't seem to find the said semispherical head bolt.
Anyone has an idea?

Ta

Monty Dog

I get small quantities of stainless fasteners from Stagonset.co.uk - but their site seems to be suspended at present. Most bike fasteners are standard metric.

holybinch

Problem I have is that the damn bolt is somewhere on the road.
Was a bit shaken when it happened and just threw the damn thing away.
And now I'm screeeeewed!

term1te

Why don't you just contact Deda, or who ever makes them, and asking for a replacement? I'm sure they would want to hear about a potential fault in one of their products.

Captain Fagor

I have a Deda RS Supercarbon seatpin in amongst my collection of unused spares. I could photograph / measure the extracted bolt and post it on this thread if that's of any help.

holybinch

Thanks Captain Fagor, it could be really useful.

Oh, and Deda's reply was "it was certainly the result of exceeding the maximum recommended torque of 22Nm on the bolt"

Captain Fagor

Here is the photo / measurements you require:



Note that my seatpin is 31.2mm oversized diameter.

Personally, I have my doubts about Deda's advice. It's a 6mm allen bolt, which would take some over-tightening in axial tension. Add to that the absence of any knurling or teeth on the parts of the seatpin that accommodate saddle tilt and I think it's much more likely that the bolt failure came about through not being tight enough, which could lead to fatigue failure.

Good luck finding a replacement.

balthazar

If the bolt failed in such a way that the two parts would fit back together precisely, then it was a fatigue failure, which isn't caused by over-tightening. Such a fatigue failure could be considered a manufacturing or design defect.

If you tightened that bolt until something failed then I'd bet one or other CFRP part would deform first– not the steel bolt or nut. Even if the bolt did fail that way, it would "neck out" at the failure point, resulting in two parts that cannot be fitted together again.

BTW, nice work Captain Fagor on the photo (and analysis).

Captain Fagor

i]Elvis[/i Thank you very much i]/Elvis[/i

holybinch

Thanks a lot guys, I've forwarded the picture to my supplier in case he needs more information.

About Deda, I guess it's the standard canned answer trying to not get involved.

moonshine

Term1te wrote:

Why don't you just contact Deda, or who ever makes them, and asking for a replacement? I'm sure they would want to hear about a potential fault in one of their products.

yip...i'd try that too.

Irrespective of cause of failure, it should be a no brainer for Deda to pop one in the post - sure, they may make a nominal charge to you, but so what..... if so pay it and geo on the road again.

have they offered that or have they point blank refused to send a bolt?

holybinch

They sent me back to my supplier.
Which I have done, he should post one for me.
Don't care about paying a couple of squids for it, as long as I can get back on the saddle.

moonshine

Sounds like a result.

Fingers crossed for a quick turnaround.

Those photos were excellent & really helped visualise the problem.

holybinch

An update on this.
So, my LBS doesn't have a spare for the bolt.
Their supplier don't have bolts either (?!)
So they're sending me back to Deda.
Am I the only one thinking their taking the pish?
Deda customer service are, it seems, on holidays till the end of August.
It is now my second week without my (4 months old) bike.

My plan:
- Write to Deda, explaining the situation
- if they refuse to pop one in the post, start raising hell with my LBS AND Deda.

Eventually, one of them will crack and GIVE ME MY *BIIIIIP* BOLT!

Rodrego Hernandez

Deda = italian = 4 weeks off through august for holiday.

keef66

It's not only the Italians. Most of my colleagues are French or German, and getting anything done in August is futile.

I'm off to check on my saddle clamp bolt; the photo looked horribly familiar :shock:

holybinch

Stupid grmbl mumble...

I HAVE to have that stupid bolt in a couple of weeks at most, I don't really see myself doing L2P on my commuter, no matter how nice it is, when I have a much better bike at home.
And I don't really feel like changing an under-warranty seat post either.

feicin' hell!

andyrr

Is it a std size post ?
Should be able to get a pretty cheap one if you get desperate then sell-on with minimal usage afterwards.

holybinch

I guess I could.
But hell, it is annoying...

crankycrank

Go to the LBS and ask if they have a similar bolt from another brand of seatpost that may work until you get the correct replacement. Although I've never seen one identical to your Dedas' there still may be something that will work. Any decent mechanic should be able to help with this.

holybinch

Quick update on this:

Deda's still completely useless.
I didn't want to go through the bodge job of using another type of bolt, especially with a 3 days ride coming, with a bad knee.
Epic Cycles have been once more faithful to their reputation and provided a seat post to do the job while we're waiting for the donkeys at Deda to do their effing job!