I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a divorce
and to lower his stress he has taken to riding his bicycle a lot. He called me
last night with a problem. His bicycle seat post - raised way up due to his
height - is bending on him. He bought a replacement and it too is bending. He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the design
goal. (A google for some exotic turnkey solution has quickly ruled out such due
to really high cost - I had no idea you could spend $200 plus on a bicycle seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

Grant Erwin wrote: (clip)Anyone "been there, done that" or have any good
ideas or input?
^^^^^^^^^^^^^^^
For minimum weight and maximum strength, he should check out titanium
seatposts. Very costly, but I believe there is no better. Does his bicycle
fit him? For a road bike, the top tube should be an inch or so below his
crotch as he stands flat-footed over the bike. If the frame is too small
for him, and he is compensating by raising the seat, that's asking for
trouble.

Two other "kluge" (sp?) fixes may be possible. One would be a sleeve that
slides over his existing post, to increase stiffness. Unfortunately, if the
post is bending just above the frame clamp (very likely,) a sleeve may not
do much good. The other possibility would be an insert to go into the post,
increasing the stiffness. Possibly a close-fitting insert at the bottom,
supplemented by a sleeve over the outside, would solve the problem.

If his bicycle frame is too small, and he doesn't want to buy another bike,
possibly a tube could be welded above the clamp, part-way up the seat post,
to add stiffness. Welding bicycle frames can be very touchy, however, and
should be done by someone who understands it.

This might look a little wierd, but would he consider a diagonal brace from
the top tube to a point somewhere below the seat (clamped at both ends--not
welded)?

Slip a piece of tubing up inside the original post to double it

"Grant Erwin" wrote in message
...
I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a
divorce
and to lower his stress he has taken to riding his bicycle a lot. He
called me
last night with a problem. His bicycle seat post - raised way up due to
his
height - is bending on him. He bought a replacement and it too is bending.
He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going
to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the
design
goal. (A google for some exotic turnkey solution has quickly ruled out
such due
to really high cost - I had no idea you could spend $200 plus on a bicycle
seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

In article , Grant Erwin says...

Anyone "been there, done that" or have any good ideas or input?

Heh - that problem happened to friend of mine years ago.

There are two solutions: 1) larger frame, 2) replace the
seatpost with solid steel, turn down the end that the
seat clamp attaches to.

Avoid aluminum in this case.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Note the common thread: "get a bigger bike!"

At 6'5" he's not in the exotic-frame catagory (quite). He should see if he
can trade his good used bike for a bigger good used bike -- using a bike
that's the wrong size is just a bummer. There should be plenty of shops in
the Seattle area that have used bikes and will do some sort of a trade.

"Grant Erwin" wrote in message
...
I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a
divorce
and to lower his stress he has taken to riding his bicycle a lot. He
called me
last night with a problem. His bicycle seat post - raised way up due to
his
height - is bending on him. He bought a replacement and it too is bending.
He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going
to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the
design
goal. (A google for some exotic turnkey solution has quickly ruled out
such due
to really high cost - I had no idea you could spend $200 plus on a bicycle
seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

Grant Erwin wrote:

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong.
... He called me
last night with a problem. His bicycle seat post - raised way up due to his
height - is bending on him. He bought a replacement and it too is bending. He
asked me to consider designing and fabricating him a suitable replacement.

I would suggest getting one of his damaged posts and measuring the wall
thickness. Hit it with a grinder and a file to at least estimate what
sort of steel and hardness you are dealing with. (The strength of
steels is very closely related to hardness.)

If it's fairly thin wall mild steel, you might just try using tube with
double the wall thickness. This will almost double the strength. I
don't think solid aluminum is likely to be very good since once you are
past a certain wall thickness you get into a region of diminishing
returns.

Don't use too hard material! This is the sort of part where failure in
bending is *much* less serious than failure by breaking.

Ted

Grant Erwin wrote:

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in
a divorce
and to lower his stress he has taken to riding his bicycle a lot. He
called me
last night with a problem. His bicycle seat post - raised way up due
to his
height - is bending on him. He bought a replacement and it too is
bending. He
asked me to consider designing and fabricating him a suitable
replacement.

Of course, for a piece maybe 18" long the cost of the material isn't
going to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in
the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the
design
goal. (A google for some exotic turnkey solution has quickly ruled out
such due
to really high cost - I had no idea you could spend $200 plus on a
bicycle seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

I have solid aluminum handlebars on my offroad motorcycle. They are 7/8 inch
diameter and virtually indestructable. If you go this route, I
recommend rounding
the edges of the hole that the seatpost slides into with a file.
Probably should do
that anyway, it prevents a stress riser.

Fred

On Mon, 16 Feb 2004 13:19:12 -0800, "Tim Wescott" wrote:
Note the common thread: "get a bigger bike!"

Most good posts have a marking for maximum height, dont go above it. If neccesary get a longer post. I have a kalloy uno one one of my bikes, its very long.
Is it a mountain bike or road?
If the problem comes from a small frame, have a look at the handlebarstem. Make absolutely sutre that its not overraised above the max marking. Failure on the
seatpost is nothing compared to a failed stem (ive seen it happen)
Henning

In article , Ted Edwards says...

Don't use too hard material! This is the sort of part where failure in
bending is *much* less serious than failure by breaking.

Ouch.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

"ff" wrote in message
...
I have solid aluminum handlebars on my offroad motorcycle. They are 7/8
inch
diameter and virtually indestructable. If you go this route, I
recommend rounding
the edges of the hole that the seatpost slides into with a file.
Probably should do
that anyway, it prevents a stress riser.

Fred


If you go with aluminum and the frame is steel be sure to use some grease on
the portion of the seatpost inserted into the frame. Bimetal fusion as it
is called in bike shop lingo corrodes the two metals over time making it
difficult to impossible to separate the two. Anyone remember the Bicology
Catalogs?

Kent

In article , Grant Erwin
wrote:

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a
divorce
and to lower his stress he has taken to riding his bicycle a lot. He called me
last night with a problem. His bicycle seat post - raised way up due to his
height - is bending on him. He bought a replacement and it too is bending. He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the design
goal. (A google for some exotic turnkey solution has quickly ruled out such
due
to really high cost - I had no idea you could spend $200 plus on a bicycle
seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington



I would go for a solid bar of 7075 aluminum machined to fit.
He will also need a beefy seat bracket to grab the seat itself.

How about thickening it by pressing a tube of smaller diameter into the
seatpost?


"Grant Erwin" wrote in message
...
I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a
divorce
and to lower his stress he has taken to riding his bicycle a lot. He
called me
last night with a problem. His bicycle seat post - raised way up due to
his
height - is bending on him. He bought a replacement and it too is bending.
He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going
to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the
design
goal. (A google for some exotic turnkey solution has quickly ruled out
such due
to really high cost - I had no idea you could spend $200 plus on a bicycle
seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

REC.BICYCLES.TECH

They would agree with get a bigger bike for starters.


"Grant Erwin" wrote in message
...
I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a
divorce
and to lower his stress he has taken to riding his bicycle a lot. He
called me
last night with a problem. His bicycle seat post - raised way up due to
his
height - is bending on him. He bought a replacement and it too is bending.
He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going
to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the
design
goal. (A google for some exotic turnkey solution has quickly ruled out
such due
to really high cost - I had no idea you could spend $200 plus on a bicycle
seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong.

The guy must be jumping tall buildings or something to bend his seat post like
that. Up until 1999 I was riding my mountain bike to and from (10 miles daily)
work plus pleasure riding any day there wasn't snow over 4 inches deep and I
NEVER had a bent seatpost. Unless he had a really cheap bike I don't see how he
could bend a post. Oh I weighed about 260 give or take ten pounds at the time.
Dennis

If it were me, solid metal. Tubing is to save cost and weight.
solid steel.

Overseas - in the Marshall Islands - we had Goose neck steering and
high seats. It was great on the back and such. Sadly they, the high handlebars
and high seats are not allowed in the states.

Some extremes were inverted frames and weird stuff - nothing to do, just dream and do.

Martin

Grant Erwin wrote:

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a
divorce
and to lower his stress he has taken to riding his bicycle a lot. He
called me
last night with a problem. His bicycle seat post - raised way up due to his
height - is bending on him. He bought a replacement and it too is
bending. He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't
going to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the
design
goal. (A google for some exotic turnkey solution has quickly ruled out
such due
to really high cost - I had no idea you could spend $200 plus on a
bicycle seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington



--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a divorce
and to lower his stress he has taken to riding his bicycle a lot. He called me
last night with a problem. His bicycle seat post - raised way up due to his
height - is bending on him. He bought a replacement and it too is bending. He
asked me to consider designing and fabricating him a suitable replacement.

Of course, for a piece maybe 18" long the cost of the material isn't going to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the design
goal. (A google for some exotic turnkey solution has quickly ruled out such due
to really high cost - I had no idea you could spend $200 plus on a bicycle seat
post!)

Anyone "been there, done that" or have any good ideas or input?

Thanks,

Grant Erwin
Kirkland, Washington

If it were me, I'd make it *solid*. It won't add *that* much weight,
and he sounds like he's big enough to peddle the little bit of extra
weight that it does add to the bike... but it won't break.
Ken.

Leo Lichtman wrote:

Grant Erwin wrote: (clip)Anyone "been there, done that" or have any good
ideas or input?
^^^^^^^^^^^^^^^
For minimum weight and maximum strength, he should check out titanium
seatposts. Very costly, but I believe there is no better. Does his bicycle
fit him? For a road bike, the top tube should be an inch or so below his

Carbon fiber.
Might be worth going to a good bike shop, and asking for a new one to fit.

"Martin H. Eastburn" wrote in message
...
If it were me, solid metal. Tubing is to save cost and weight.
solid steel.

Overseas - in the Marshall Islands - we had Goose neck steering and
high seats. It was great on the back and such. Sadly they, the high
handlebars
and high seats are not allowed in the states.

Some extremes were inverted frames and weird stuff - nothing to do, just
dream and do.

Martin


Actually, there is no law preventing any choice of steering or seats, with
the exception of the fact that most states and
cities do require the use of both hands on a handlebar of some type.
It's probably just the case that whatever you rode over there isn't popular
here.
Folks here have been building some pretty shoddy examples of "tall bikes"
for some years now.
You can start here to get an idea - no regulations against wierd designs (or
shoddyness!)
http://www.geocities.com/ratpatrolhq/BikesTall.html

Brian

Brian Smith wrote:

"Martin H. Eastburn" wrote in message
...

If it were me, solid metal. Tubing is to save cost and weight.
solid steel.

Overseas - in the Marshall Islands - we had Goose neck steering and
high seats. It was great on the back and such. Sadly they, the high

handlebars

and high seats are not allowed in the states.

Some extremes were inverted frames and weird stuff - nothing to do, just

dream and do.

Martin



Actually, there is no law preventing any choice of steering or seats, with
the exception of the fact that most states and
cities do require the use of both hands on a handlebar of some type.
It's probably just the case that whatever you rode over there isn't popular
here.
Folks here have been building some pretty shoddy examples of "tall bikes"
for some years now.
You can start here to get an idea - no regulations against wierd designs (or
shoddyness!)
http://www.geocities.com/ratpatrolhq/BikesTall.html

Brian



Maybe it was were I lived in Texas. Here in Ca. - skate boards are banned most places
as no one wants a kid to fall in there parking lot.

The basic one is a long Bolt - and steel (blake pipe IIRC) - The bolt was typically
a thin rebar or other steel rod, the handle bar bolt cut off and welded on the ends
of the rebar - long bolt! - cut the bottom of the pipe and- hum forget about the handle bars -
were they welded or drawn by the pipe. hum. Someone will figure -

Maybe I can dig up a picture and scan it in. :-) It was only 40 years ago.

Martin

--
Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

On Mon, 16 Feb 2004 09:36:32 -0800, Grant Erwin
vaguely proposed a theory
.......and in reply I say!:

At 240 lb, why bother about light weight parts? Solid steel or very
thick pipe would make little difference. Aluminium would be useless
IMO, solid or not. It would bend easier than a steel pipe.

I have a friend who is about 6'5" tall and weighs maybe 240 pounds, a big
solid blue-collar type, very strong. He has recently been involved in a divorce

Of course, for a piece maybe 18" long the cost of the material isn't going to
bankrupt anyone. I was thinking chrome-moly tubing if I can find it in the
right diameter, and forging a swaged-down neck area. He is thinking solid
bar of aluminum. Minimum weight and cost with maximum strength is the design
goal. (A google for some exotic turnkey solution has quickly ruled out such due
to really high cost - I had no idea you could spend $200 plus on a bicycle seat
post!)

Anyone "been there, done that" or have any good ideas or input?

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