i have just gotten my first 29" unicycle and its a muni (i wont be doing much offroad but some light to very light offroad) and i must say that there is a giant height difference between the 29" and the 20" (my only 2 unicycles). now in terms of seatpost height, the lowest i can make the seatpost go makes my leg perfectly straight when reaching for the pedal at the lowest point of rotation. that being said my foot reaches the pedal, and i dont have to go on my tiptoes, but it just perfectly touches it when my leg is fully extended, is this a good height? many people say that your knee should be bent a little bit, and ive been having just a little trouble keeping my balance on this thing, especially seeing as i was able to ride my 20" unicycle for 2 blocks without falling, and on this 29" i can barely make it 20 feet. help anyone?
I’ll give the two cents out of my experience:
A slight bend is what I’d want for an easy distance ride; like a sidewalk, greenway, or relatively smooth fire road.
Edit: I’ll get rid of the long winded thing I wrote about muni seat height. I reread your post and saw that you aren’t interested in that for now.
Stick with the 29er. I went from a 24 to a 26, then to a 29 so I had a smoother transition. At first the 29er felt off, I could ride it just fine but it felt like I was constantly fighting the thing to keep if from veering off to one side. With time it became my preferred uni. Maybe I just had to wear the tire down to even it out?
IMO the slight bend in the knee suggestion is really to help alleviate pains that can crop up when you start doing distance. It’s easier to learn/adjust to a new size uni with the seat lower than the ideal setting and gradually raise it until you find that sweet spot. You really don’t want to learn/adjust with the seat too low but it sounds like that isn’t the problem. It sounds like you could really benefit from lowering the seat but it also sounds like you don’t even have that option. Can you lower the seat at all? How tall are you?
i am 5’ 9" and my inseam length is 34 inches, when i bought the unicycle it said the minimum inseam requirement for the post i bought (300mm) was 33.5 inches, so i thought it would be alright. still the question remains, will it hinder me in terms of learning or speed if my leg isnt slightly bent?
I think so… hopefully others will chime in shortly. Everyone is a bit different but I like bend in my leg. I don’t like the feeling that I have to reach as far as I can with one leg when the pedals are vertical, it introduces some vulnerability into the equation for me. A slight bend gives you a little “standing room.” Sometimes you need to absorb a bump with that bend in your knee, sometimes you need to ride a few seconds out of the seat to promote blood flow, etc. If your leg is already extended as far as it will go you’d have a hard time standing on the pedals when they are in the vertical position.
It sounds like you are more than tall enough for a 29er. Did/can you cut the seat post down? They are really meant to be cut down and not accepted “as is.” The recommendation is to have at least 2" in the frame. With that recommendation I like to leave enough post to have at least 2 inches in the frame when the pedals are slightly out of reach, that way I make sure not to cut off too much - which can be a costly mistake that would make you buy a new post - but you definitely want to cut off enough so you can comfortably ride.
yea the other day whilst i was trying to cope with it, i dropped off a curb and tried to stand up to no avail, the brunt of the force went were the sun dont shine 
i instantly fell off, hehe. i am able to cut the post down but like you said, if i cut off tooo much it could be a costly mistake, which obviously worries me. and just so you know i have the seatpost well over 2 inches in, i have it so low that if i lowered it any more the seat will touch the tire (it is already poking out of the bottom of the slot in the frame). thanks for your opinion, it really helps.
I did the same, jumped from a 20 to a 29 and yes, the difference was huge. I found that when I was starting out I needed the seat set up with my leg nearly straight - if I put the flats of my feet on the pedals I’d have no bend in my knees at all, but a slight bend with my the balls of my feet on the pedal. IMO, this is as high as any seat should ever be, bike or uni.
As I’ve gotten better (can now ride basic trails, get over maybe 2" rocks & roots) I’ve found it easier to ride with the seat a lot lower, maybe 2". I think the big difference was that I did not have the strength to stand up and pedal for very long then and now I can, so I can get more power for short bursts even with a lower seat.
Bottom line: if I were you I’d cut a couple of inches off the post - at some point you’re going to want to try lower; it sounds like you couldn’t try higher even if you wanted to.
thank you for your opinion, seeing as i have 2 other people with the same advice i guess ill be trimming off like 1" then testing it, then 2". thanks guys!
Yeah I was paranoid when it came time to trim my seat post as well. I bought a used 29er and the post was too short, so that meant an immediate $50 investment. I cut off a half inch at a time I was so paranoid about having to buy another… that said I could still easily lop off another 2" from where I settled and probably need to trim it down another inch or so.