I'm trying to find a new seatpost binder bolt for my Miyata 914. I loaned it (the bike, not the bolt) to somebody, then as I was tightening the bolt after raising the seatpost back to the right height for me, it just snapped under a normal amount of torque.
Anyway, it's not like the bolts on any of my other bikes. It's 6 mm in diameter and about 25 mm long. One end is an allen-head cap screw--takes a 5mm wrench, I think. The outside (of that end) is cylindrical and 10 mm in diameter--it fits into a recess in the seatpost lug. The other end is hex nut that fits into a hexagonal recess on the other side of the lug.
I found a 25 mm x 6 mm stainless steel allen-head cap screw at the hardware store that seemed as if it should fit. The barrel-shaped end with the allen head fits the frame recess perfectly, and the shank is the right size, too. The problem is that the nut I bought with the bolt--which measures 10 mm across the flats--is a fraction of a mm too large to fit into the frame recess.
What gives? Do I need a special proprietary nut and bolt? If so, where do I find one? Alternatively, where do I find a 6 mm metric nut that measures 9.5 mm across the flats? This is the kind of problem I would have expected with a French bike, not a Japanese one. Any advice or information gratefully received.
JV