Ispd!!!

gordito8me said:

I think, just as unicycling companies have done with the ISIS hubs, they
should do the same thing with seatpost diameter! I'm looking at frames
to replace my lx and there are just tons of diameters. I'm setting the
standard at 25.4 mm seeing as on udc, that's what most of the seatpost
diameters are.

their are lots of people who ride with different size seat posts and
and they either don't care what size or they ride with a given size for
a reason. it would be immpossible to get everyone to ride with a given
size because I don't think Kris Holm would start making 25.4 seat
posts/frames just to set a standard.
with the hubs, they are producing a new model each year, so they are
constantly changing so it is easy to get all the brands to a certaint
style.
but with the seatposts they are mainly only reinforcing them, not
rebuilding them

--
torkerdx

GILD said:

If it was a naked young lady, would we be shouting about sexual
objectification?

gordito8me said:

it's like running across the highway at rush hour. Dangerous, stupid,
but not really that fun.

skrobo said:

i would rather ride a brick than have a folding tire

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You're missing the point slightly, crank standards are necessary because
to define a crank interface you need a lot of factors i.e. axle
diameter, number of splines, spline profile, taper etc. Seatposts are
defined by a single factor i.e. diametre so there's no need for a
complex set of definitions. In the same way that not every crank is
ISIS, not every post is the same diametre, and a good thing too,
different posts do different jobs, why on earth would you want to
constrain a freestylist and a triasl rider to have the same size post,
when their needs are clearly so different?

--
kington99

Dave

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International seatpost design? 😄

I usually see 25.4 and 27.2mm seat posts. Those are two most common
sizes I have noticed.

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The reason there are so many seatpost diameters is that not all
unicycles (or bicycles) use the same frame tubing and frame material.
Some tubing has thicker walls, some is double butted, some is a stock
size while some is custom. Different materials (different alloys of
aluminum, different steels) need different wall thickness and diameters
for the needed strength.

There is much in terms of engineering design and available tubing sizes
that influences the choice of a seatpost size. Specifying a specific
size to be the standard will limit the design choices available to
frame designers trying to optimize their frame design for weight,
strength, and other features. It will limit the material choices. It
will make some unicycles more expensive because they'd need to use
custom tubing just to get the standard ID for the standard seatpost
size. Standardizing on a single seatpost diameter is not a good idea,
especially for higher end unicycles.

Standardizing on a common size for the low end unicycles would be
possible and we've already got that for the most part. Most low end
unicycles use 7/8" (22.2mm) seatposts. 1" (25.4mm) is more recent and
getting more popular. So there are two common sizes available that
covers pretty much all low end (and many high end) unicycles. That's
reasonable.

27.2mm is a common size for aluminum frames. Aluminum frames need
larger diameter tubing due to the nature of aluminum (strength, etc.).
So you end up needing a larger diameter seatpost with aluminum frames.
Most aluminum unicycle frames use 27.2mm seatposts.

So in the unicycle world the most common sizes are 7/8" (22.2mm), 1"
(25.4mm), and 27.2mm and that covers the majority of frames. Some
others (like Hunter) use different sizes. That's more sane that the
bicycle world where there are lots of other sizes in common use.

--
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