I cant’t seem to find this anywhere, but does anyone know the inner diameter of a 5 bolt 110 mm bcd chainring?
I need to make a chainguide/bashring and can’t seem to find the numbers anywhere.

It’ll vary by crank – hence you sometimes have to file the tabs down a bit. The bolts are M8, so I assume the holes are very slightly larger than 8mm, plus say 3 mm of material inside the bolt, so… 96mm or so, maybe.

Yeah, that’s what I came to. It’d be reasonably easy to make it under size and take it out I suppose.
I just assumed it would have been a fairly standard dimension.

measure the OD of a crank?

Difficult to do that with any real accuracy as no two opposing holes. A quick bit of trigonometry would get there, but I’d measure the chainring you’re taking off.

It’s a bit difficult on a 5 arm crank. I’m at work anyway 😆
just wondered if that information might be at hand

Same problem with the chainring as it’s “armed” rather than a solid circle.
I think I’ll just measure back from the bolt holes…

Same problem with the chainring as it’s “armed” rather than a solid circle.

Nah I meant measure the hole diameter and the amount of material on the inside of the hole.

Yeah, surely you’d assume the BCD of 110mm and just measure from the entre of one chainring hole to the inner edge of the chainring and you’d get the figure to take off the 110mm (twice this value obviously 😛 )

It’s a bit difficult on a 5 arm crank.

measure the radius and double it. 8)