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Broken steel road bike fork



 
 
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  #1  
Old September 29th 09, 05:37 AM posted to rec.bicycles.tech
[email protected]
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Posts: 2
Default Broken steel road bike fork

So, I've been noticing that the front brakes of my road bike
were acting "grabby" in that the front would shimmy pretty
badly just as I'm coming to a stop. The rims felt a little
sticky, maybe some Gatorade got on them and it hasn't really
rained in a while. I cleaned the wheels last night and rode
into work today. It was still bad, but didn't seem as bad.
This has been going on for a week, I didn't think anything of
it. I decided to not ride after work and just come home, coming
down the driveway, the grabby-ness was really pronounced, so
I figure that the brake pads must be contaminated with something.
When I took the wheel off, my heart skipped a beat. Without much
effort, this is the result:

http://www.bitrealm.com/misc/fork/p1000783.jpg
http://www.bitrealm.com/misc/fork/p1000784.jpg
http://www.bitrealm.com/misc/fork/p1000785.jpg

It was hanging by no more than 2mm of steeel. I shudder when I
think of the roads I was about to go on, including one really
bad bump at the bottom. I don't think it would have held together
and when you lose the front like this, it's going to be bad.

The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. There hasn't been any accident damage since
I put this fork on the bike. The crack was almost all the way
through, starting from the BACK of the fork leg.
  #2  
Old September 29th 09, 08:23 AM posted to rec.bicycles.tech
Hank
external usenet poster
 
Posts: 887
Default Broken steel road bike fork

On Sep 28, 9:37*pm, wrote:
So, I've been noticing that the front brakes of my road bike
were acting "grabby" in that the front would shimmy pretty
badly just as I'm coming to a stop. *The rims felt a little
sticky, maybe some Gatorade got on them and it hasn't really
rained in a while. *I cleaned the wheels last night and rode
into work today. *It was still bad, but didn't seem as bad.
This has been going on for a week, I didn't think anything of
it. *I decided to not ride after work and just come home, coming
down the driveway, the grabby-ness was really pronounced, so
I figure that the brake pads must be contaminated with something.
When I took the wheel off, my heart skipped a beat. *Without much
effort, this is the result:

http://www.bitrealm.com/misc/fork/p1...k/p1000785.jpg

It was hanging by no more than 2mm of steeel. *I shudder when I
think of the roads I was about to go on, including one really
bad bump at the bottom. *I don't think it would have held together
and when you lose the front like this, it's going to be bad.

The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. *There hasn't been any accident damage since
I put this fork on the bike. *The crack was almost all the way
through, starting from the BACK of the fork leg.


Yikes. Congrats on catching that before disaster struck.
  #3  
Old September 29th 09, 01:28 PM posted to rec.bicycles.tech
semi-ambivalent[_2_]
external usenet poster
 
Posts: 126
Default Broken steel road bike fork

On Sep 28, 10:37*pm, wrote:
So, I've been noticing that the front brakes of my road bike
were acting "grabby" in that the front would shimmy pretty
badly just as I'm coming to a stop. *The rims felt a little
sticky, maybe some Gatorade got on them and it hasn't really
rained in a while. *I cleaned the wheels last night and rode
into work today. *It was still bad, but didn't seem as bad.
This has been going on for a week, I didn't think anything of
it. *I decided to not ride after work and just come home, coming
down the driveway, the grabby-ness was really pronounced, so
I figure that the brake pads must be contaminated with something.
When I took the wheel off, my heart skipped a beat. *Without much
effort, this is the result:

http://www.bitrealm.com/misc/fork/p1...k/p1000785.jpg

It was hanging by no more than 2mm of steeel. *I shudder when I
think of the roads I was about to go on, including one really
bad bump at the bottom. *I don't think it would have held together
and when you lose the front like this, it's going to be bad.

The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. *There hasn't been any accident damage since
I put this fork on the bike. *The crack was almost all the way
through, starting from the BACK of the fork leg.



You might invest in at least one lottery ticket about now. You know,
before it all wears off.
  #4  
Old September 29th 09, 01:42 PM posted to rec.bicycles.tech
jim beam[_5_]
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Posts: 941
Default Broken steel road bike fork

On 09/28/2009 09:37 PM, wrote:
So, I've been noticing that the front brakes of my road bike
were acting "grabby" in that the front would shimmy pretty
badly just as I'm coming to a stop. The rims felt a little
sticky, maybe some Gatorade got on them and it hasn't really
rained in a while. I cleaned the wheels last night and rode
into work today. It was still bad, but didn't seem as bad.
This has been going on for a week, I didn't think anything of
it. I decided to not ride after work and just come home, coming
down the driveway, the grabby-ness was really pronounced, so
I figure that the brake pads must be contaminated with something.
When I took the wheel off, my heart skipped a beat. Without much
effort, this is the result:

http://www.bitrealm.com/misc/fork/p1000783.jpg
http://www.bitrealm.com/misc/fork/p1000784.jpg
http://www.bitrealm.com/misc/fork/p1000785.jpg

It was hanging by no more than 2mm of steeel. I shudder when I
think of the roads I was about to go on, including one really
bad bump at the bottom. I don't think it would have held together
and when you lose the front like this, it's going to be bad.

The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. There hasn't been any accident damage since
I put this fork on the bike. The crack was almost all the way
through, starting from the BACK of the fork leg.


chrome plate is bad for fatigue - it contains many fatigue initiators.

for the future, consider quality cfrp - unless abused, it's pretty much
"fatigue proof".
  #5  
Old September 29th 09, 03:21 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 2
Default Broken steel road bike fork

On Sep 29, 5:42*am, jim beam wrote:
On 09/28/2009 09:37 PM, wrote:



So, I've been noticing that the front brakes of my road bike
were acting "grabby" in that the front would shimmy pretty
badly just as I'm coming to a stop. *The rims felt a little
sticky, maybe some Gatorade got on them and it hasn't really
rained in a while. *I cleaned the wheels last night and rode
into work today. *It was still bad, but didn't seem as bad.
This has been going on for a week, I didn't think anything of
it. *I decided to not ride after work and just come home, coming
down the driveway, the grabby-ness was really pronounced, so
I figure that the brake pads must be contaminated with something.
When I took the wheel off, my heart skipped a beat. *Without much
effort, this is the result:


http://www.bitrealm.com/misc/fork/p1000783.jpg
http://www.bitrealm.com/misc/fork/p1000784.jpg
http://www.bitrealm.com/misc/fork/p1000785.jpg


It was hanging by no more than 2mm of steeel. *I shudder when I
think of the roads I was about to go on, including one really
bad bump at the bottom. *I don't think it would have held together
and when you lose the front like this, it's going to be bad.


The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. *There hasn't been any accident damage since
I put this fork on the bike. *The crack was almost all the way
through, starting from the BACK of the fork leg.


chrome plate is bad for fatigue - it contains many fatigue initiators.

for the future, consider quality cfrp - unless abused, it's pretty much
"fatigue proof".


This fork was on the bike for about 8 years and had probably around
12K miles on it in that time.

I would like to find a 1" threaded replacement that has eyelets for
fenders,
but they seem pretty thin on the ground. I can find the exact same
fork
shown here (in black) that I could still buy. It was a 200 mm steerer
tube with 35mm of threading. Cut, it is 190mm with 25mm of threading.
The one shown here was made for 27" wheels and I just run long reach
calipers. I had to have the crown race cut from 27 to 26.4mm.

If not, any 1" threadless forks with eyelets and room for fenders?

Anyone, Bueller?
  #6  
Old September 29th 09, 04:29 PM posted to rec.bicycles.tech
Tim McNamara
external usenet poster
 
Posts: 6,945
Default Broken steel road bike fork

In article
,
wrote:

On Sep 29, 5:42*am, jim beam wrote:
On 09/28/2009 09:37 PM, wrote:

So, I've been noticing that the front brakes of my road bike were
acting "grabby" in that the front would shimmy pretty badly just
as I'm coming to a stop. *The rims felt a little sticky, maybe
some Gatorade got on them and it hasn't really rained in a while.
*I cleaned the wheels last night and rode into work today. *It
was still bad, but didn't seem as bad. This has been going on for
a week, I didn't think anything of it. *I decided to not ride
after work and just come home, coming down the driveway, the
grabby-ness was really pronounced, so I figure that the brake
pads must be contaminated with something. When I took the wheel
off, my heart skipped a beat. *Without much effort, this is the
result:


http://www.bitrealm.com/misc/fork/p1000783.jpg
http://www.bitrealm.com/misc/fork/p1000784.jpg
http://www.bitrealm.com/misc/fork/p1000785.jpg


It was hanging by no more than 2mm of steeel. *I shudder when I
think of the roads I was about to go on, including one really bad
bump at the bottom. *I don't think it would have held together
and when you lose the front like this, it's going to be bad.


The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. *There hasn't been any accident damage since
I put this fork on the bike. *The crack was almost all the way
through, starting from the BACK of the fork leg.


The crack initiating in the back of the leg is not unusual.

chrome plate is bad for fatigue - it contains many fatigue
initiators.


Chrome plating *can* result in embrittlement but does not necessarily do
so. Millions of bikes and other load bearing appplications are chromed
without such failures happening.

The reason for the failure seem pretty self-evident in the photo. Note
how the crack followed the shore line of the socket so perfectly, and
note the relative thicknesses of the metal. Note also the lack on a
reinforcement tang on the inside of the fork leg.

for the future, consider quality cfrp - unless abused, it's pretty
much "fatigue proof".


More clueless advice from "jim beam."

This fork was on the bike for about 8 years and had probably around
12K miles on it in that time.

I would like to find a 1" threaded replacement that has eyelets for
fenders, but they seem pretty thin on the ground. I can find the
exact same fork shown here (in black) that I could still buy. It was
a 200 mm steerer tube with 35mm of threading. Cut, it is 190mm with
25mm of threading. The one shown here was made for 27" wheels and I
just run long reach calipers. I had to have the crown race cut from
27 to 26.4mm.

If not, any 1" threadless forks with eyelets and room for fenders?


Harder to find these days since most aftermarket forks are aluminum or
CF, lack eyelets and are for 700C wheels (if the bike was made for 27"
wheels, going to a 700C fork will affect the geometry). But I would
think that any bike shop with a QBP account could order you a fork to
fit. Or you could have one made, but that would be expensive.
  #7  
Old September 29th 09, 10:00 PM posted to rec.bicycles.tech
someone
external usenet poster
 
Posts: 2,340
Default Broken steel road bike fork

On 29 Sep, 16:29, Tim McNamara wrote:

Chrome plating *can* result in embrittlement but does not necessarily do
so. *Millions of bikes and other load bearing appplications are chromed
without such failures happening.


More likely the cause of embrittlement is what causes it with non-
chromed forks. Overbrazed.

Current common practice is to use oxy-acetylene torch and spelter wire
because it is quicker overall. I suspect the higher temperatures
obtainable with oxy-acet ensure a deeper penetration of the spelter,
alloying with the steel, causing the embrittlement. In skilled
experienced hands, oxy-acet does produce excellent results when there
are no distractions. I would certainly favour a builder which had the
certification of qualification from a technical college in the use of
oxy-acetylene for brazing if I was unable to locate one with historic
recommendation. That (college cetificate) does not necessarily
qualify him to braze cycle forks. And be careful that builders
although say they do the work, leave spotty Nigel to do the
preperation.

Hearth brazed forks heated with natural gas may also suffer with
brass embrittlement due to excessive duration in the flame. Good
preparation is the key. No cutting with abrasive grit, only by file,
plenty of flux in the joint and the use of granular spelter inside the
end of the fork reduce the heat exposure of the steel so keeping the
alloying depth to a minimum at the edge of the crown. I think it be
the filling from the end of the crown rather the end of the fork to be
the killer.

Nigel, may of course used carbarundum instead of the file and scraper
to prepare the forks and crown and if he's applied a paste flux, how
much water?


The reason for the failure seem pretty self-evident in the photo. *Note
how the crack followed the shore line of the socket so perfectly, and
note the relative thicknesses of the metal. *Note also the lack on a
reinforcement tang on the inside of the fork leg.


Overbrazed.


for the future, consider quality cfrp - unless abused, it's pretty
much "fatigue proof".


More clueless advice from "jim beam."


overbrazed.
  #8  
Old September 30th 09, 03:42 AM posted to rec.bicycles.tech
jim beam[_5_]
external usenet poster
 
Posts: 941
Default Broken steel road bike fork

On 09/29/2009 08:29 AM, Tim McNamara wrote:
In article
,
wrote:

On Sep 29, 5:42�am, jim wrote:
On 09/28/2009 09:37 PM, wrote:

So, I've been noticing that the front brakes of my road bike were
acting "grabby" in that the front would shimmy pretty badly just
as I'm coming to a stop. �The rims felt a little sticky, maybe
some Gatorade got on them and it hasn't really rained in a while.
�I cleaned the wheels last night and rode into work today. �It
was still bad, but didn't seem as bad. This has been going on for
a week, I didn't think anything of it. �I decided to not ride
after work and just come home, coming down the driveway, the
grabby-ness was really pronounced, so I figure that the brake
pads must be contaminated with something. When I took the wheel
off, my heart skipped a beat. �Without much effort, this is the
result:

http://www.bitrealm.com/misc/fork/p1000783.jpg
http://www.bitrealm.com/misc/fork/p1000784.jpg
http://www.bitrealm.com/misc/fork/p1000785.jpg

It was hanging by no more than 2mm of steeel. �I shudder when I
think of the roads I was about to go on, including one really bad
bump at the bottom. �I don't think it would have held together
and when you lose the front like this, it's going to be bad.

The shimmy was the wheel moving back and forth due to the fork
leg being fatigued. �There hasn't been any accident damage since
I put this fork on the bike. �The crack was almost all the way
through, starting from the BACK of the fork leg.


The crack initiating in the back of the leg is not unusual.

chrome plate is bad for fatigue - it contains many fatigue
initiators.


Chrome plating *can* result in embrittlement but does not necessarily do
so. Millions of bikes and other load bearing appplications are chromed
without such failures happening.

The reason for the failure seem pretty self-evident in the photo. Note
how the crack followed the shore line of the socket so perfectly, and
note the relative thicknesses of the metal. Note also the lack on a
reinforcement tang on the inside of the fork leg.


oh, timmy the retard is now a fatigue expert!!! tell us timmy, which
end of the microscope did you cram up your ass when you learned all this
bull****?



for the future, consider quality cfrp - unless abused, it's pretty
much "fatigue proof".


More clueless advice from "jim beam."


which is the larger force timmy - 1600N or 5000N?



This fork was on the bike for about 8 years and had probably around
12K miles on it in that time.

I would like to find a 1" threaded replacement that has eyelets for
fenders, but they seem pretty thin on the ground. I can find the
exact same fork shown here (in black) that I could still buy. It was
a 200 mm steerer tube with 35mm of threading. Cut, it is 190mm with
25mm of threading. The one shown here was made for 27" wheels and I
just run long reach calipers. I had to have the crown race cut from
27 to 26.4mm.

If not, any 1" threadless forks with eyelets and room for fenders?


Harder to find these days since most aftermarket forks are aluminum or
CF, lack eyelets and are for 700C wheels (if the bike was made for 27"
wheels, going to a 700C fork will affect the geometry). But I would
think that any bike shop with a QBP account could order you a fork to
fit. Or you could have one made, but that would be expensive.


what ridiculous retardation.
  #9  
Old September 30th 09, 03:47 AM posted to rec.bicycles.tech
jim beam[_5_]
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Posts: 941
Default Broken steel road bike fork

On 09/29/2009 02:16 PM, Still Just Me! wrote:
On Tue, 29 Sep 2009 05:42:51 -0700, jim wrote:

for the future, consider quality cfrp - unless abused, it's pretty much
"fatigue proof".


The fact that it was steel and demonstrated fatigue instead of just
failing catastrophically (like crappy fiber does when it fails) is the
only thing that saved him.


er, so a failure is better than a non-failure??? because you're
confused between fatigue and over-load or abuse??? jeepers dude, you're
winning that stupidity contest again!



As always, your advice is useless.


no, i cast pearls before ignorant incapable swine.
 




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