due ruote 

I need to replace the bolt on a Campy single bolt post. Should I just buy a bolt that fits at the hardware, or does it need to be something special? Thanks.

(edit) A quick check online informs me that this isn’t going to be easy to find. Maybe a new post is in order.
I believe the size is M8 x 35 mm fine thread. Can anyone confirm that? And if a source is known, I am all ears.

miamijim

They’re a very odd thread. Every blue moon during a solar flare, if you get lucky, eBay’s crystal ball gets a hit.

I see there’s a few listed now started at $25-ish. If it’s M8x1.0 pitch then try Amazon or Home Depot. I saw 50mm length on Amazon.

merziac

That sucks, is the broken piece stuck in the cradle?

We had this a few weeks ago on an older version with the regular hex head bolt, snapped just like this once the OP was able to get a hold of it right proper.

I have one that was slipping and wouldn't tighten enough. I got it apart, cleaned and burnished? the threads on the wire wheel, anti-seize and a well fitting 6 point wrench FTW.

Seems like these and many others need to be serviced better, more often if we want them to keep going.

due ruote 

Nope, not stuck at all. In fact, I just unscrewed it with my fingers.
This one broke while I was riding - an interesting sensation. At least I found the clamp bits without too much trouble.
The bolt broke where the threads begin, which I suppose was predictable. Maybe it was over-torqued at some point.
I will probably wind up ordering a bolt from Italy. Worst part is the delay, but I guess that's why we need multiple bikes.

merziac

Excellent, as we know even and sometimes especially Campy can be cursed, sounds like it had a good run. I personally would massage all parts similar to as I outlined above.

I would also be inclined to explore a better substitute to avoid this going forward, maybe even rethread the cradle for a common bolt and maybe even add a locknut on top of the cradle.

We know from the SP binder bolts and these that Campy may not maintain fasteners at the same level as the parts and pieces themselves.

As noted in the other binder bolt thread, they are cut threads instead of rolled and from my observation not that well done IMO being sharp and jagged creating many stress risers therefore doomed to fail as they often seem to do.

The wire wheel and anti-seize or grease can go a long way towards preventing this.

Bobjackson

https://www.mcmaster.com/screws/syst...d-type~socket/

Mc Master Carr, they are a good place for fasteners as in 8×1.0 seat bolt/screw.

merziac

This is a very good workaround,

https://www.bikeforums.net/22642405-post19.html

due ruote 

That's cool, but I think maybe that's a C-Record (?) post and what I have is a Victory. The post has a cavity where the bolt head goes so it's not visible from that view.
As luck would have it, I went to the hardware and used their thread board to determine that it is in fact a M8 x 1.0 x 35mm bolt that I need. And although they only stocked coarse thread, I was able to find one on Ebay for $7. Cool, right? Almost. Only then did I realize that I had found all the bits except the contoured thrust washer (or whatever it's called) that goes under the bolt head. I returned to the scene of the crime and did a few slow passes, but no luck finding it.
So now I am looking at this seatpost and thinking OK, I will never find one of these bits, but really how hard could it be to fab. one?
Does anyone have a Victory post laying around? I would love to see a picture of the wedge piece and get a couple measurements. I tried Velobase but keep getting security warnings, so I haven't actually seen what's there.

merziac

I may have one, I'll check and see. Also might be able to fab or modify the UNO parts, maybe?

Really shouldn't be that hard to cobble something, even if temporary.

merziac

@due ruote

Mine is the style with a slot like yours I think, has a big stout bolt, may have been changed and the little concave/flat squarish washer, its good hard stuff so....

Might be a challenge to fab a really good substitute but wouldn't stop me from trying.

due ruote 

Is the concave washer alloy or steel?

merziac

Steel, serious, hard and very well made.

due ruote 

Thanks. That’s what I was afraid of. I don’t really have the facility for something like that.
(Edit) I gave this a little more thought, and perhaps I will give this a go after all. I found a chunk of 1/2" steel rod laying around, and it looks like a decent fit. I do have a vice, angle grinder, files and a drill press... @merziac, if you (or someone else) are able to post a photo of the piece, that would be very helpful. If the post is installed and you don't want to unsaddle it, I get it. Thanks.

merziac

Atta boy

On it, standby.

I don't think it really has to be that hard but it and the bolt on this one seem to be what you would want long term, weight weenieness not withstanding and not ever a concern for me.

merziac

@due ruote

So yours didn't have this as it should, pic of the underside?

12 x 14mm

Hondo6

Velobase updated their site's SSL certificate yesterday evening, so you should be able to visit it now without issue/warnings.

due ruote 

Thanks a lot for posting that. I am not sure we have the same seatpost.
Mine is decidedly concave where the washer sits, which is why I mentioned trying to use round stock to make the part.
I am pretty sure mine had some type of washer in there, but I didn’t have the presence of mind to search for it when the post exploded. Probably got picked up by a car tire and is who knows where by now.
Pics:

due ruote 

Thanks for that.
Here's a clue to what it should look like from Velobase. It sort of looks to me like it's alloy after all.

merziac

DOH! Yep, you're correct, the UNO workaround might work by turning the half round 45 degrees. I would hesitate to make one out of steel as the wedging might hack on the SP if it has to be good and tight as they usually do., I would get some alloy rod or an UNO that would have all you need to get back on the road even if you had to rework the half round to fit yours.

due ruote 

Yep, I think once I get my hands on a bit of alloy rod stock, it will be a snap. I'll report back for posterity.

due ruote 

Something compelled me to go back for one more look and voilà:



And btw it is steel.

Thanks for going along - sorry it was all for naught, but who doesn’t like a happy ending?

merziac

No worries, like I said, Atta boy.

Not surprised the original is steel, I was concerned about fabbing one and having it be off enough somewhere to get stuck or blow up the program.

Factory stuff can be sneaky "oh *****, I thought it could be a little smaller, bigger, longer or shorter", snap, crackle, BANG!

Glad you found it.

LeicaLad 

I'm sorry that I come to the party late. If you are still seeking a replacement bolt, Jim Merz has made some of titanium. I have one from Jim on the same seat post. I no longer worry about that seat post.

He did have a few on hand, last I knew. When he makes a custom bit (like Ti crank bolts), he generally makes a few. Ask him.



Cheers!

due ruote 

Thanks. The one I ordered is steel, grade 12.9, which is supposed to be pretty darn strong. It's black, but it won't be visible. Hoping it will suffice. I'm not very large and generally not super hard on gear.