Im after getting a 456 for my lad and hes 5,10" so am i right in thinking hed be best on a 16". Hell want to do a few jumps and stuff on it so probably best to be on the small size

16 ought to be OK if you want a chuckable frame
I am 5'11 and a 14 inch is way too small( my son has one).
I ride an 18"

DO a search this gets asked quite a lot.

Some people will recommend 16" but I'm the same height and ride the 18". Find it more than fine for a few jumps. There's not that much difference in the two except for the BB to TT height. Both have massive standover anyway.

I'm 5'10.5" and went with a 16". I run a 70mm stem and a lay-back post (needs to be a long-un) and it's a great play-bike. If he was doing longer rides then perhaps the 18" but Brant advised on the 16" for buggering about on and I think he was spot-on.

ok cheers ill go 16" i think

im five ten and have a 16 with 70mil stem and inline post long one mind lol i had an 18 before it but prefer the smaller one but either would fit tbh

A smidge over five ten here and went with a 16" as per Brants suggestion as well – absolutely perfect – plenty long enough tt length and loads of standover. Cracking bike!

another 5tenner here and i have the 16" its 'bob on' for everything

best bike i own