ISO hanger bolt for Suntour Cyclone rear derailer
 

I found a Suntour Cyclone rear derailer in a box of parts at a yard sale, pretty dirty but cleaned up very nicely, I was pretty excited. Ready to go now except it is missing the hanger bolt.
The thru hole is about 11mm, there is a counterbore of about 18mm that the bolt head would settle into. The thickness at the thru-hole (the "grip" of the bolt) is about 6mm.
It looks like the one here: disraeligears.co.uk/Site/SunTour_Cyclone_GT_derailleur_5905_2nd_style.html
except no black color.
Would have posted in the Want to Buy forum but it wont let me.
Any pointers would be appreciated

didnt measure correctly, counterbore is 17mm dia, not 18, for what its worth

That's going to be hard to find. And even if you do find one from a cyclone or v-series derailleur that looks similar, it may not be a perfect fit. Your best bet is to find a cheap donor derailleur.

It doesn't have to be perfect. But it does have to be real close to perfect. For example, if it isn't quite long enough, and the derailleur locks (doesn't swing freely) when the bolt is tightened, you might be able to use blue loctite to keep the bolt in place even with it not secured all the way down. I have done this with success with a Sprint derailleur.

Agreed with SR. Some bike bolts are industry standard in their relative dimensions, others are not. Der mounting bolts tend to be rather specific. Andy

If you have a friend with a lathe it is not difficult to make one out of 4130 cr-mo steel. You may have to use a die for the threaded portion if the lathe is not equipped for making metric threads.

I have seen (and still see) hanger bolts on ebay, but listings don't give information about bolt diameter or grip length, and sellers often can't help when I contact them to ask.
I measured the thru-hole as being .435 inches, just a shade over 11mm. Started looking for an M10-1.0 button head cap screw, wrap a 5mm wide strip of soda can aluminum around it to make up the extra mm.
Seems those bolts are not all that common either, Grainger and the like only have M10-1.5, but they have to be somewhere

Dont know anyone with a lathe, there are small machine shops where I live but they are probably $100/hr at least, having one specially made wouldn't be an option

Try posting in the Classic and vintage ISO/Trade thread: https://www.bikeforums.net/classic-v...rt-5-a-43.html

You might get lucky.