I'm restoring an old Atala for my son. The frame takes a 26.8 post. The binder clamp does have notches on both sides. I measured the outer distance and come up w/18.8mm. Nearly all the binder bolts I see are 19mm. Am I going to need to shim it with a washer or do I need a shorter bolt? And I measured with the post snugly in place.

Thanks for any help.

Obviously, only one side needs to be notched, use a washer on one side, grind the nut side shorter if you have to

I was hoping common sense would prevail.

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Are we talking about a seat lug with integral binder ears or the design with a separate seat binder collar?





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Here is a 17mm seat bolt:

Integrated like the top photo.

Thanks for the link!