Seat Post Suspension

“Antonio A. Ortiz” <aao4247@acs.tamu.edu> writes:
>I was at a bike shop the other day and I saw a seat post with suspension. Has
>anyone ever had a suspensioned Uni? Or is it not a good Idea?

I rode a bicycle with a suspension seat post (I think it was a “gas-spring” like
the ones used on car hatchbacks - they are preloaded by gas pressure so they
don’t move until you exceed the preload - then it is like a spring/damper…
Anyway, the point is IT WAS INCREDIBLE!!! I would have run right out and
gotten 2 for my tandem, except that they’re not made in the same small diameter
as my Schwinn seat post tube. Uhhhh, and they are over $100 each!

As I recall, you have to buy them to match your weight - so that the preload is
correct for you. Otherwise it would be too stiff or too soft.

Use one on a uni? It would probably work. I often wondered about building a uni
with a mountian-bike fork (the kind with shocks). Is that what a “muni” is?

Mark

I was at a bike shop the other day and I saw a seat post with suspension. Has
anyone ever had a suspensioned Uni? Or is it not a good Idea?

Antonio

Re: Seat Post Suspension

In a message dated 95-12-12 15:20:25 EST, Bierne Konarski wrote:

>If the goal is to have springy shocks to help with jumps, this won’t work
>because the crank is part of the wheel, not the frame. What am I missing here?

I don’t think they’re as interested in springy jumps as they are in having a
softer ride. Am I right? After riding 36 miles on New York City roads on a
hard-rubber tire big wheel you will try lots of things!

Somebody please build one of these, spend however much it costs, guinea-pig it
and tell us how it works out, okay? Thanks.

In the States there seems to be a common fork on some of the Cannondale mountain
bikes that has a single shock at the top of the fork crown. If using a mountain
bike suspension fork (instead of one made specifically for seat posts), make
sure it’s adjustable so you can raise the stiffness. The bicycle’s front fork is
not made to support the entire weight of the rider, and so a regular one would
probably bottom out just by sitting on it.

John Foss unicycle@aol.com

Re: Seat Post Suspension

> I don’t think they’re as interested in springy jumps as they are in having a
> softer ride. Am I right? After riding 36 miles on New York City roads on a
> hard-rubber tire big wheel you will try lots of things!

Right, I think the issue is ride comfort.

> In the States there seems to be a common fork on some of the Cannondale
> mountain bikes that has a single shock at the top of the fork crown. If using
> a mountain bike suspension fork (instead of one made specifically for seat
> posts), make sure it’s adjustable so you can raise the stiffness. The
> bicycle’s front fork is not made to support the entire weight of the rider,
> and so a regular one would probably bottom out just by sitting on it.

I have a Cannondale with the HeadShok (their spelling). It uses 4 vertical rows
of 22 needle bearings each (at the points of the compass), plus one of several
varieties of spring/damper mechanism. Some models use elastomer springs and no
damper, some elastomer springs and an oil damper, some an adjustable air spring
with an oil damper. The extremely cool thing is that, once you have the
headshock headset, the shock mechanisms are all interchangeable. For biking, to
my mind and backside, it works great and is an elegant solution to achieving
ride, control, and fork rigidity simultaneously.

I think it would be worth getting hold of a broken (for bicycling purposes)
Cannondale frame, and cannibalizing the head/fork assembly. However,
Cannondale also sells a suspension seatpost for about $100 US, that (I think)
uses needlebearings to control movement (but I don’t know what they use to
damp oscillations). As someone pointed out, the twisting we apply to the seat
riding a uni may exceed what the seatpost was designed for, but mountain
biking is not exactly gentle, and anyway, the only way to find out is to try
it and see how easily it breaks. Perhaps I will do this, but it’s not top of
my list right now. (I’m in the process of changing jobs.) I add my voice to
the chorus of recalcitrants encouraging other intrepid souls to experiment and
tell us the results.

-Mark

Re: Seat Post Suspension

Hi John Foss. I’m unicycling up here in Inwood? Where are you? Any ideas where
to get a giraffe here in NYC?

Shawn Hill.