Plan on losing the outer ring on my daughters bike and will need to pad out the chainring bolts. - will m10 washers suffice? How thick is a chainring usually - >5mm?
Washers tend to be too big in diameter and interfere with the spider arms, Wheels Manufacturing make proper spacers for this, but I'd just buy some shorter chainring bolts, just because it looks neater.
I have used copper sump washers successfully - can't remember size (useful, I know) but were dirt cheap for a pack on ebay. They have a small outside diameter compared with standard washers.
I've used washers but had to file flats on them to get them to sit straight on the cranks.
Or just cut the tabs off the outer chainring and use them as spacers?
As per Wwaswas... been going strong for 12 years now....
DrP!!
I've used M10 spring washers. Nice and small outer diameter. You do need to do them up tight to sit flat but it won't rattle loose