I know what bolt to put in the starfangled nut, but what size is it? I had always though it to be M5 (takes a 5mm allen key) but it would appear that the bolt is actually 6mm, meaning it’s an M6 – which suggests that the bolts holding mudgards in place are M5, since they’re 5mm bolts. Is that right?

M5 = 5mm dia, uses 4mm allen key
M4 = 4mm dia, uses 3mm allen key

see here

Star fangled nut is M6

Most brazed lugs will be M5

So yes, you are correct.

Sounds right to me. It’s certainly an M6 bolt for the star fangled doofer.

you can really start confusing things when you get onto thread pitch as well though… 😉

M6x1.0mm for a SFN 😉

M6x1.0mm for a SFN

mine’s a lot longer than that?

igmc.

okey doke. It’s just that I ordered two packs of M5 bolts for another purpose and was surprised that they weren’t the same size as my SFN bolt. 😳

this was supposed to be a cheaper way of fitting a mudguard than buying a mudhugger but given my ineptitude at measuring and knowing what size bolts to order, it’s becoming quite expensive. Eejit.