semach.the.monkey said:-About -12 inches? I've always taken it to be exactly 12 inches 😄
He's doing a GCSE so he'd better start calling it 30cm.
semach.the.monkey said:Anyway, as far as exact measurements go, it will depend on the height of
the rider, crank length and saddle height preference. You could
calculate what height your saddle height would be for a 36" unicycle
based on your 20" unicycle - It's 8" more (Wheel center to floor is 10"
on a 20" uni, and 18" on a 36", therefore it's a difference of 8"😉.
STM
Surely that presumes he'd be running the same crank length on a 20" as
a 36". <=125mm is ordinary on a 20" but >=150mm is ordinary on a 36".
Then there's the tyre. His 20" could have a ~2.5cm and and a 36" have a
~5cm or even up to 7.5cm!
My advice, don't presume anything. Go to the extremes, calculate the
highest seat height for a 205cm guy on a 36" with 100mm cranks and a
low profile saddle and the lowest to be a 120cm child on a 16".
Build some mock-up wheel sizes / crank setups with cardboard and get
some people of varying heights to lay down while you measure their
inseam to pedal positions. You don't need actual wheels, just props of
the right length.
I used to prop my 20" on a guitar stand very similar to this one
[image: http://www.djmmusic.com/mmDJM/Images/3491-AI.gif]
The principle of an all-size uni stand is pretty similar IMO.
If you're going to go for any size of rider then you could either make
the centre piece a 3+ part telescopic, or try a design like
[image: http://www.djmmusic.com/mmDJM/Images/G39-AI.gif]
Though the weight of a 36" tilted slightly back will probably be a bit
severe so you'll want to give it a back leg. Also, you'd have to very
carefully consider the position of the pedals on this sort of model.
--
mattsmith
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