broken seat post

I broke my seat post mounting yesterday. Not a huge surprise, I guess, with
all the hopping I've been doing lately, but I've only been hopping around for
a few months.

I broke the metal plate that the seat is bolted to and the seat post tube is
welded to. Snapped it right in front of the post, presumably from pulling the
uni up by the handle during hops.

Tom Miller will send me a new one for $20. Yay! My hero! He was apologetic about
charging me $8 for shipping and handling, but it's a better deal than I'd get
from a local metal shop, and I'm happy to help keep him in business.

He said that Miyata made that piece stronger around 1993 or so. Mine is from
September 1992 (as indicated by the "9" and "92" on the bottom of the seat), so
the replacement should last a bit longer.

Luckily, I can borrow a friend's Schwinn until mine is fixed. No
downtime for me!

Aah, Good old Schwinn comes through again!!

[color=blue]> Today my Miyata seat post broke, right below the three little tack welds by[/color]
[color=blue]> the big H-shaped plate. Has anybody else had this problem?[/color]

Me. The older posts were worse. More recent ones have a larger radius in the
part that breaks, but they just aren't made for the kind of abuse some of us
give them. From all the pushing down and pulling up on the seat, eventually
that part will fatigue and crack apart.

In the past, the nylon Miyata seat bases used to break across the front of where
the seat post plate ended. Since then, that plate has been extended and I'm not
aware of this seat cracking problem anymore. Now the weakest link in the Miyata
seat/post is right where yours broke. All of my posts have eventually died in
this area.

[color=blue]> Is there any heat treatment that will be affected by my welding it back[/color]
[color=blue]> together?[/color]

Unless you beef up that whole area, I think welding will be a waste of time.
It's low grade metal, and may not hold up well to welding at all. As far as heat
treating, I doubt that it was used on such a simple part. If you have the means,
I recommend making a stronger seat post. You might be able to keep the top plate
and just weld on new pipe, or start from scratch if possible.

I have a nice post on my DM ATU, made by local rider Terrell Williams. I would
have preferred aluminum, but he can only weld steel. We made our own seat post,
with a gusset on the bottom that leads up to a second plate under the front
bumper. This keeps the post rigid, so the same stresses are not being applied at
the spot where your post broke. It should last relatively forever. Also, the
Miyata seat base should also never break. Now all I have to do is replace seat
covers and bumpers when they wear out.

Sorry it's probably hard to visualize without a picture. I should get
some posted...

Stay on top, John Foss, the Uni-Cyclone http://www.unicycling.com

"Are we eating Chinese again tonight?" -- More than one rider in China
at UNICON X