I have a pair of new current production 86 BCD Stronglight chainrings that I want to mount on a Sugino crankset, but that's complicated by the fact that the chainrings aren't countersunk for the heads of the chainring bolts. As a result, when the "nut" half of the bolt passes through the inner chainring and the crank spider, it ends up flush with the outside face of the spider--it doesn't protrude beyond it the usual 1-2 mm to allow the outer chainring to engage the shank of the nut, keeping the ring centered.
One solution--the best one, really--would be to take the rings (at least the inner ring) to a machine shop and have the holes countersunk. I could do that and maybe will, but would prefer not to spend the $50 that's probably going to cost.
A simpler option would be to find some longer chainring bolts. All of the double bolts (or rather, the nut portion of each bolt) in my parts box measure 9 mm long overall, including the head. If I had a set of bolts with an overall length of 10 or 11 mm (again, I'm talking about the length of just the nut part of each nut/bolt) I could dispense with the countersinking and just bolt the suckers on.
Are bolts available in that length, does anyone know?
A third option, I guess, might be to cut down a set of triple chainring bolts made to mount the third chainring with spacers--at 16 mm, they're WAY too long to use uncut--but that seems like kind of a kludge.
Any suggestions gratefully accepted.
For what it's worth, I bought the chainrings from Spa Cycles in England. They're the dural version, which are a few dollars less than the Zicral version, which are supposed to be more durable, and also come with countersunk bolt holes. My bad luck, though: the Zicral rings have apparently been discontinued, and they didn't have them in the sizes I needed. Dang it!
JV

I didn't know that Sugino ever made an 86bcd crankset.

I've seen only SR-Apex and stronglight cranks with the 86bcd.

Couldn't you just countersink the small ring enough to let the nut reach through?

And I believe that on occasion I've had to set up cranks with just the heads of the bolts securing the big ring counter-bored holes on location, and that it actually stayed put, presumeably since steel chainring bolts can be heavily tightened.

I've even re-located chainring bolt holes using a rat-tail file, and also trimmed the tabs to rest on the ledges of the crank spider arms using a bigger half-round file.
It didn't seem to be such a critical issue as far as everything lining up perfectly, and I did it entirely by hand and by eyeball with seemingly excellent results on a Triomphe crankset for example, so as to fit a 36t MTB chainring.

You're right, it is an SR crankset--my mental chain skips sometimes. Unless someone tells me where to find some slightly longer bolts, I probably will have the bolt holes in the small ring countersunk by 1.5 mm or so.
JV