I have a 96 Marin Rocky Ridge, the nipples are all breaking, they have a slightly thinner tread to normal bike nipples, your info about them being 1.8mm makes sense - do you know where you can buy these? ebay/amazon etc?Length or diametre? Length would depend on the number of spokes and hub/rim combo. If you mean the diametre, Marin used 1.8mm nipples on those bikes just to make life difficult :~)
hey thanks man, I've just bought these https://www.ebay.co.uk/itm/264893261413?var=564737201355DT Swiss and Sapim make 1.8mm nips. Off the shelf from amazon, st john street cycles, ebay.
Still used for lighter wheels.....i may even have a bag of used marin wheelsmith ones.....will have to check.....stand by....