What annoys me is when you find a manufacturer quoted ERD and then other websites (SJS Cycles springs to mind ... ) quote a completely different figure.
This just isn't helpful.
well it depends who is correct...?.
Several manufacturers (mavic and rigida/ryde spring to mind but there are others) have form for quoting an ERD figure which is actually a NSD figure. Use that and you will end up with spokes that are ~2mm too short, which is no good at all.
FWIW when some vendors (Spa and SJS spring to mind) state an ERD on their website for a well-established product I'd be inclined to trust that if it differs from the manufacturers figure, since they also build with the rims they sell. IIRC when Spa sell rim, spokes and hubs together they provide some kind of guarantee that they will fit?
cheers
