I have SKS fenders on a couple of bikes -- a 1972 Puch with non-threaded eyelets and a modern (2004) Felt with standard eyelets. The Felt takes the SKS M5 bolts without issue, and the Puch works just fine because I have the fastening nuts.

However, when I try the SKS bolts in the threaded eyelets of my 72 Motobecane Grand Record and my 86 Univega Gran Premio, the bolts don't thread in. Do these older bikes have a different thread pitch and/or diameter for their eyelets?

I found this thread that alludes to arcane threading in older bikes, but could find no further discussion:

http://www.bikeforums.net/bicycle-me...ifference.html

Thanks so much...