Spoke length?

[richiebozza]

Afternoon all,

I'm building some 20" wheels (I have Sun Big City Lite 48 hole Rims) but wonder how you know what length spokes I need. I have seen 218mm spokes, but how do you know what hubs they would fit, for example would they be wrong or right for high flange hubs like these:
https://www.ebay.co.uk/itm/184397799990

Are hubs maybe standard sizes? For example low and high flange being two standard set diameters? And if so, what length spokes would each need for a 20" wheel?

Thanks!

[Spen69]

There's a sticky on it mate 

Everything you need to know all in one place 

http://www.radbmx.co.uk/forum/index.php/topic,136816.0.html

[richiebozza]

Thanks Spen!