Originally Posted by
tomtomtom123
The threaded hole was meant to be future-proof in case I switched to a frame that only has one eyelet so that I can attach the mud guard strut to the hole.
The mounting hole is not threaded, but I made it 5 mm instead of 6 mm that the original strut had. I noticed that the original aluminum strut with a 6mm hole had indentations from the bolt threats that seem to imply that the 6mm hole being too large for the M5 bolt allowed it to shift around on the bolt.
Good reasons.
While you could have used a backing nut for the fender strut bolt, the thickness of your strut allows threading, and if you wanted, adding a backing nut anyway, helps prevent it coming loose.
Yeah a bolt clearance hole should typically be 1/32" larger which is 0.79 mm, so 5.79mm, but I prefer a closer slip fit, especially with smaller holes; A closer slip fit keeps the bolt a bit straighter when loaded in lateral bending. If I was making it, I would drill it 5mm and see if the bolt fit before going any larger. Typically, drill bits run out a bit and the hole is automatically a touch bigger than the drill bit.