seat post size

i have a 26in inseam should i get a 300mm or a 400mm for a

When in doubt then use common sense: you can’t make short seatpost longer, but you can make long seatposts shorter.

i am just trying to save asmuch as i can

Well, if you look thoroughly at your own link, you can see that 28" is the minimum inseam length required for 300 mm. So it seems that you can save $5…

400mm is probably overkill

I just bought that same uni although not the signature model. You know the only difference between the signature model and the regular is black spokes and white rim. Easy way to save $20 if you are pinching pennies. I got the 400mm post because I’m 6’1’’. The bottom of the seatpost is about an inch above the tire. I could have easily gone with the 300mm. Also make sure you get the moments. I got the 125’s because I’m a pretty casual rider, and I like to cruise around.

i am 6’2

Ask UDC when you buy it. The will take into account what frame it is and how tall you are. And has been said it does not take a lot to cut down a seat post.