Death wobble in front bars!

kjparker wrote:
On Oct 21, 9:30�am, Jay Beattie wrote:
On Oct 20, 2:35�pm, kjparker wrote:





Hello,
I have an elderly (circa 1978) Raleigh Grand Prix road bike that I am
using for my daily commuter. �It is in other wise fantastic
condition,
but just recently it has developed a wobble in the front end.
It manifests itselft when riding as for lack of a better description
a
wobble in the handle bars, with the wheel moving (slightly) side to
side.
If I were to tap with my palm on the side of the head tube, I can see
a slight bounce coming from the lower part of the headset, where the
fork goes through. �I have dropped the fork, inspected the bearings,
re-packed them etc, yet the problem persists!
I also repeated the palm tapping just on the fork with the wheel
mounted, and it was solid.
Any advice on how I could resolve this? �I really love this bike, and
would love to keep riding it!
Keith
Check your front wheel bearings -- and I assume you do not have any
broken frame tubes. �When you get shimmy with a broken tube, the frame
is about to fail. �If nothing has changed with your bike (and it
previously did not shimmy), then the shimmy might be rider induced. I
fell and broke some ribs on a descent a few years ago, and for a
period of about six weeks, I would get terrible shimmy any time I
descended more than about 40mph. �It was a little PTSD and rib pain
from my fall that caused me to stiffen up through the shoulders while
descending. It went away. Any reason why you might be stiff through
the upper body? -- Jay Beattie.- Hide quoted text -

- Show quoted text -

The wheel has (as part of the trouble shooting process) had it's
bearings re-packed / replaced. Axel is perfectly fine, not broken.
Wheel spins true.


I did turn it upside down and check the lugs, and I noticed that on
the underside of the bottom tube, there is a gap, about the thickness
of a hair in between the lug and the tube. I assume that if this was
a "factory" gap, it would have been filled with paint, and not have
been a gap.


This makes me assume that there is a crack


What would be my options now?



paint can't stop cracks from opening and closing. and if it's doing
that, the paint will crack also. is the paint cracked or merely absent?

oh, wait, to sell you on my big tube frame theory, i need to tell you
yes! the frame is cracked! it needs to be replaced immediately!

alternatively, you can post a pic of what you describe so we can be more
sure.

On Oct 21, 3:14*pm, jim beam wrote:
kjparker wrote:
On Oct 21, 9:30 am, Jay Beattie wrote:
On Oct 20, 2:35 pm, kjparker wrote:

Hello,
I have an elderly (circa 1978) Raleigh Grand Prix road bike that I am
using for my daily commuter. It is in other wise fantastic
condition,
but just recently it has developed a wobble in the front end.
It manifests itselft when riding as for lack of a better description
a
wobble in the handle bars, with the wheel moving (slightly) side to
side.
If I were to tap with my palm on the side of the head tube, I can see
a slight bounce coming from the lower part of the headset, where the
fork goes through. I have dropped the fork, inspected the bearings,
re-packed them etc, yet the problem persists!
I also repeated the palm tapping just on the fork with the wheel
mounted, and it was solid.
Any advice on how I could resolve this? I really love this bike, and
would love to keep riding it!
Keith
Check your front wheel bearings -- and I assume you do not have any
broken frame tubes. When you get shimmy with a broken tube, the frame
is about to fail. If nothing has changed with your bike (and it
previously did not shimmy), then the shimmy might be rider induced. I
fell and broke some ribs on a descent a few years ago, and for a
period of about six weeks, I would get terrible shimmy any time I
descended more than about 40mph. It was a little PTSD and rib pain
from my fall that caused me to stiffen up through the shoulders while
descending. It went away. Any reason why you might be stiff through
the upper body? -- Jay Beattie.- Hide quoted text -

- Show quoted text -

The wheel has (as part of the trouble shooting process) had it's
bearings re-packed / replaced. *Axel is perfectly fine, not broken.
Wheel spins true.

I did turn it upside down and check the lugs, and I noticed that on
the underside of the bottom tube, there is a gap, about the thickness
of a hair in between the lug and the tube. *I assume that if this was
a "factory" gap, it would have been filled with paint, and not have
been a gap.

This makes me assume that there is a crack

What would be my options now?

paint can't stop cracks from opening and closing. *and if it's doing
that, the paint will crack also. *is the paint cracked or merely absent?

oh, wait, to sell you on my big tube frame theory, i need to tell you
yes! *the frame is cracked! *it needs to be replaced immediately!

alternatively, you can post a pic of what you describe so we can be more
sure.- Hide quoted text -

- Show quoted text -

I'm at work atm, so cant take a pic, but there is a bit of both.
Missing paint inside lugged area, and cracked paint.

Happy to buy a big tube frame, but my budget currently wont stretch
there, which is why i'm riding a 30 year old roadie!

On 21 Ott, 05:15, "Leo Lichtman" wrote:
Keith Parker wrote: (clip) just recently it has developed a wobble in the

front end.(clip)
^^^^^^^^^^^^^^^^^^^^^^"jim beam" wrote: (clip) this is function
of that old frame having skinny main tubes. (clip)

^^^^^^^^^^^^^^^^^^^^^
Jim, I'm curious how you figure that this frame developed skinny main tubes
as it got old.

By repeatedly experiencing relativistic contractions, you stupid
idiot.
It's all written, open source through internet.

Sergio
Pisa

On Tue, 21 Oct 2008 03:15:08 GMT, Leo Lichtman wrote:

Keith Parker wrote: (clip) just recently it has developed a wobble in the
front end.(clip)
^^^^^^^^^^^^^^^^^^^^^^
"jim beam" wrote: (clip) this is function
of that old frame having skinny main tubes. (clip)
^^^^^^^^^^^^^^^^^^^^^
Jim, I'm curious how you figure that this frame developed skinny main tubes
as it got old.

jim beam mode on

You idiot, that's what shimmy /does/ to frame tubes.

jim beam mode off

kjparker wrote:
On Oct 21, 3:14�pm, jim beam wrote:
kjparker wrote:
On Oct 21, 9:30 am, Jay Beattie wrote:
On Oct 20, 2:35 pm, kjparker wrote:
Hello,
I have an elderly (circa 1978) Raleigh Grand Prix road bike that I am
using for my daily commuter. It is in other wise fantastic
condition,
but just recently it has developed a wobble in the front end.
It manifests itselft when riding as for lack of a better description
a
wobble in the handle bars, with the wheel moving (slightly) side to
side.
If I were to tap with my palm on the side of the head tube, I can see
a slight bounce coming from the lower part of the headset, where the
fork goes through. I have dropped the fork, inspected the bearings,
re-packed them etc, yet the problem persists!
I also repeated the palm tapping just on the fork with the wheel
mounted, and it was solid.
Any advice on how I could resolve this? I really love this bike, and
would love to keep riding it!
Keith
Check your front wheel bearings -- and I assume you do not have any
broken frame tubes. When you get shimmy with a broken tube, the frame
is about to fail. If nothing has changed with your bike (and it
previously did not shimmy), then the shimmy might be rider induced. I
fell and broke some ribs on a descent a few years ago, and for a
period of about six weeks, I would get terrible shimmy any time I
descended more than about 40mph. It was a little PTSD and rib pain
from my fall that caused me to stiffen up through the shoulders while
descending. It went away. Any reason why you might be stiff through
the upper body? -- Jay Beattie.- Hide quoted text -
- Show quoted text -
The wheel has (as part of the trouble shooting process) had it's
bearings re-packed / replaced. �Axel is perfectly fine, not broken.
Wheel spins true.
I did turn it upside down and check the lugs, and I noticed that on
the underside of the bottom tube, there is a gap, about the thickness
of a hair in between the lug and the tube. �I assume that if this was
a "factory" gap, it would have been filled with paint, and not have
been a gap.
This makes me assume that there is a crack
What would be my options now?
paint can't stop cracks from opening and closing. �and if it's doing
that, the paint will crack also. �is the paint cracked or merely absent?

oh, wait, to sell you on my big tube frame theory, i need to tell you
yes! �the frame is cracked! �it needs to be replaced immediately!

alternatively, you can post a pic of what you describe so we can be more
sure.- Hide quoted text -

- Show quoted text -

I'm at work atm, so cant take a pic, but there is a bit of both.
Missing paint inside lugged area, and cracked paint.

Happy to buy a big tube frame, but my budget currently wont stretch
there, which is why i'm riding a 30 year old roadie!

understood. my commuter is built on one of these:

http://nashbar.com/profile.cfm?categ...eid=&pagename=

zero frills but utterly stable. for a clydesdale that used to think
shimmy was just a fact of life when i rode steel, this is the frame that
changed my mind. and encouraged me to do some homework on the subject.

Hi,

This makes me assume that there is a crack

What would be my options now?

Please in your own interest, assume there is a crack and don't ride the
bike until this is resolved. You'll add to the damage and you'll
endanger yourself if you ride.

As to the options:
(1) have a frame-builder exchange the cracked tube. If this is an
old-fashioned bike, it's likely a lugged steel frame and can be
repaired. This will take a few days and cost between twenty and a few
hundred dollar.

(2) get a new frame. Completely dismantle your old one and use the parts
to build up the new bike. You might want to replace the fork,
head-bearing, bottom bracket and some other parts. Make sure the new
frame fits your geometry and your old bikes parameters (otherwise
re-using old parts gets difficult).

(3) get a new bike - which might be cheaper than (2) if many parts of
your old bike would need replacement and/or you would have the bike shop
do the work.

Don't mind having a classic steel-frame. They're great *if* you like
them, no matter what some people try to make you believe. I would never
want to use an aluminium or plastic frame for my upright touring bike
(which has to carry me and lots of luggage), but would be fine with an
alu.-frame on a recumbent bike or a sporty race bike (though I dislike
oversized tubing on any upright frame just for the looks).

If you decide to go for a new bike, be sure to test-ride a recumbent
bike if possible. It's such a completely different feel ;-)

Good luck..

Mike Jacoubowsky wrote:
1. it should NEVER be the riders fault. under any circumstances.

2. i have two big tube aluminum frame bikes. [i.e. STIFF] that
absolutely will not shimmy under any circumstances.

You're saying shimmy can only be the fault of the frame, nothing else?
And that it shouldn't matter whether someone is riding no-hands or not?
That a bike should be designed in such a tame manner that it's
impossible to develop a shimmy no matter what the rider does
(positioning or whatever)?

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"jim beam" wrote in message
t...


1. it should NEVER be the riders fault. under any circumstances.
------------
I tend to agree with Jim, it's the frame design. I've fought shimmys
for years with all the black magic that rbt could dish out, and it would
help a little, but finally got a bike with a big stiff downtube, and all
that unstable crap just went away. Bikes have been designed wrong for
years, they are starting to get it right.

"sergio" wrote: By repeatedly experiencing relativistic contractions, you
stupid
idiot. (clip)
^^^^^^^^^^^^^^^^^^^^^
So now I think I understand why Albert Einstein looks so worried in the
famous photo of him riding a bicycle.

On Oct 20, 11:15*pm, "Leo Lichtman"
wrote:
Keith Parker wrote: *(clip) just recently it has developed a wobble in the

front end.(clip)
Jim, I'm curious how you figure that this frame developed skinny main tubes
as it got old.

I see it in nursing homes all the time. Some frames get skinnier as
they get older :

MD

" wrote: I see it in nursing homes
all the time. Some frames get skinnier as they get older :
^^^^^^^^^^^^^^^^^^^
And they wobble, which further confirms the premise.