cpsqlrwn

Looking for a seatpost binder bolt for a Merckx Century. Prefer Campagnolo. The one that broke appears to be a 10 mm across the bolt head. Never used one of those before but I think replacing it with an 8 mm might not be a good idea. All the splines are in place and look good.10 must be on there for a reason. If anyone is willing to chime in on that I'd appreciate it. Thanks for any help or info

malcala622 

Check out this item on OfferUp. https://offerup.co/g2RhaL72fDb

Chombi1 

Be aware that the newer (not sure of the cut off year. I think the older ones with the coarser serrations were supossedly better.) seatpost binder bolts from Campy have a tendency to crack and break. Some people had such bad experiences with them constantly breaking that they switched over to a more reliable binder bolt like the ones from Sugino.
Might not be Italian, but it might avoid a sudden bout of PITA on the road.

cpsqlrwn

So I have been fiddling around with these Campy splined seatpost binder bolts (having broken 2 of them) and for anyone that is interested, I think I stumbled into a somewhat more reliable solution for making them work a little bit better. The broken bolt I removed from the bike and the one that I am using as a replacement is the one having a 10mm bolt head, and when fully threaded, the length inside both bolt heads is 19 mm. The bolts come with a washer, so after you have broken one or two of these bolts, you then have one or two extra washers on hand. It appears that applying an extra washer or two to the non splined end relieves a little of the stress to the threaded bolt as it tightens down on the binder. The threaded area of the bolt does not travel as far into the female housing of the splined piece and any minimal misalignment of the two binder ears seems to result in less stress to the threaded area because it is not threaded as far into splined housing where it is more likely to bind up. I used two washers total, which seemed like the best balance between relieving the stress on the threaded piece as it was tightened and insuring there was adequate threading inside the splined piece to insure a strong install. Just thought I would pass this on.

merziac

You can also grind down the female side so it does not bottom out and break itself. the other thing is to use a small dab anti-seize so it doesn't break from seizing either. The added washers also lower the friction of tightening it as well.

repechage

@merziac is correct, BUT, sometimes the seat lug ears are not aligned. Not good.

merziac

And that can aggravate the problem while the fix can often mitigate some of that, especially if its not very severe.

I've seen very few that were not helped quite a bit by a little lube and a proper bolt even with some misalignment.

cpsqlrwn

This was the biggest problem with mine. You could look at the ears from a short distance directly behind the seat tube and see that they were not quite aligned. My screw was never close to bottoming out in the splined half. The problem was that the further the screw went into the splined half, the more the misalignment stressed the screw. As the length of the misalignment was shortened through the tightening process, the pressure created by the small misalignment became slightly more extreme. The deeper the screw went into the misaligned area the greater the stress of the directional pressure being placed upon it. Putting the additional washers outside the ears on one side allowed the bolt to be tightened the necessary amount with the distance between the bolt ends being a little longer than before (the screw did not go in as far) and the additional length slightly reduced the stress on the screw. Stated another way, the misalignment of the screw was made less compact and therefore, less severe, through the lengthening of the entire distance of the bolt assembly, slightly reducing the stress.

repechage

Time for a traditional bolt and nut, maybe a socket head cap screw and a nylock nut. I have used that from time to time.

cpsqlrwn

That was my fallback strategy if I couldn't make the Campy bolt work. A steel M6 allen head capscrew, 20 or 25 mm in length, a washer or two, and a hex nut. Not the most eloquent solution, but at that point, functionality rules.

TimmyT 

cpsqlrwn I think I have one in the parts box. I will look for you tonight.

repechage

there are M7 cap screws and nuts. AN washers often can be found with reduced outer Diameter compared to SAE.