I’m going to build a 20" freestyle uni
how do I know what size to get???
>Cranks
>Frame
>anything elce I might need to know reguarding sizes or building in general
Thx
Cranks you really can’t tell except for what you enjoy. I would suggest starting off with something around 110-115 mm long though.
For the frame, I don’t really understand your question.
Are you building the uni from pre existing parts or are you building it from scratch, custom and stuff?
custom and stuff… Not pre-exsisting…
all new
How advanced a freestyler are you? Most good freestylists would use 114mm or shorter cranks, and have the largest frame that they could fit on, but if you’re only just starting out I would advise longer cranks (like 125mm) and not to worry so much about the frame, having the high seatpost clamp doesn’t really have any effect until you start doing stand up tricks, and you porbably need to get settled with a seat heihgt that you like and then measure to find the biggest frame that will fit, obviously if you buy too tall frame you can’t out the seat any lower.
That helps alot really. 
Good one Ivan 
Unless you cut the frame’s neck. Do it only an inch at a time.
True, but then you also have to recut the notch for the frame to close around the seatpost, and it’s never going to look as good as an uncut frame.
I’m not about to cut my seatpoast any shorter and REDO the notch for the clamp… but ne wayz… ok… I was doing alot of thinking and looking and searching last night and I think I know what I’m getting… thankyou.
Dude what?
"You need at least this step length for this frames
300mm: 74cm
400mm: 84cm
500mm: 94cm"