Need serious help with seat binder!

So I brazed on a seat binder bolt. Cleaned it all up, threw in a seat post to test it out, and the bolt gets super tight before it actually pulls the seat tube tight on the post. Like super tight. I cleaned up the threads too after brazing to ensure the threads were good and smooth. The bolt goes in nice and smooth but it won’t clamp the post at all. Not even a little bit.

I’ve never experienced this before and not sure how to fix this.

Any thoughts as to what the problem could be or how to remedy this?

I cut the slot after I brazed on the binder. Could this be the issue? The bolt goes in very smooth and then it hits a wall and get extremely tight without clamping down on the post.

Thanks in advance.


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You got any pics of the binder/slot? And specs on the seat tube being clamped ? It can take a surprising amount of force to close up a seat tube, especially thicker/larger diameter seat tubes/welded in collars of modern bikes. Usually a slot with a drilled relief at the bottom would allow enough flex but I’ve seen a few builders use a T shaped slot to allow for more movement in the ‘wings’ of the clamped section. I have a hardtail with this style slot so will upload a pic when I get home.

Yeah I’ll get a pic up here. It’s weird. I can compress the area with some large pliers but for some reason I think that binder is literally getting bound up from the bolt.

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Here’s a pic from the rear. Seat tube is a 29.8 external butted number. I can insert the post, take large pliers and clamp the tube on on the post with no issues. Whatever is happening, it’s coming from the bolt. Like I said it seems like the binder is binding up when the bolt starts to tighten up.

Is there a bit of thread remaining in the bolt head side that the fastener is tightening on? might just need to get in there with a drill on the non threaded side if there is


I was going to say the same thing. It’s one of those little things that you can just completely miss and tear your hair out trying to fix, then feel like a bonehead when you spot it (sanity check: the binder piece on the right should be a straight hole that the bolt can pass through easily, the piece on the left should be threaded).

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Thank you guys. I drilled it out and it works like a champ.

HAHAHA! Ok I’ll admit it’s been a while since I’ve used a binder but damn, this post makes me look like an idiot. Can I delete it?! I don’t recall ever having this problem prior. Maybe I didn’t even think to check the bolt head side. Hell, I went and looked at the other binders that I have and some are fully threaded and some aren’t. Weird.


Don’t delete, some other builder may be able to learn from this.


I’ve had this same thing happen and never figured it out! Ended up cutting it off and using a seat post clamp. Thinking back after reading this post, I’ll bet it was the same issue.


Glad you found the issue. Defo don’t delete this thread. I reckon I would 100% made the same mistake so this is good learning for others.

For the record here’s the ‘T’ shaped slot I was on about. It’s an old image courtesy of Darren over at Larkin Cycles.


I wasn’t totally serious about deleting, but I definitely feel silly after getting it sorted.


I bought the same binder once and had the same confusion until I realized I needed to drill one side out to make it work. No shame in posting stuff like this! But seriously, I don’t know why a binder was ever sold like this unless it was a mistake.