I have an old fuji touring bike I have restored. It has threaded fender/rack mounts on the frame and fork. I am wondering if there is a standard for tread size for rack mounts on vintage bikes. Or at least common types. I would like to avoid walking my bike into Lowes if I can avoid it. Thanks for the help!

The older the bike, the bigger the chance of non standard threads. Some older bikes use the next size up metric. I think m5 is standard.

IME, the vast majority are 5mm x 0.8mm (which happens to be compatible with SAE 10-32). A few oddballs are 6mm x 1mm. And a few are unthreaded.

Yeah, probably M5, possibly M6, and in the case of some 70s Schwinns a few actually had imperial threading for the fender mounts.

Thanks for the feedback.

My frame has three sets of mounts, a set on the forks and two sets on the rear dropouts. The set on the forks and one set on the dropouts are M6. The other set on the back is M5. I got some nice black allen keyed screws for all three sets for a few bucks at Lowes.

Thank you for the help!

Cool, i had a miyata like that. Never understood it but hey if it works youre good.