A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Carbon Forks Reliability = paranoia or truth?



 
 
Thread Tools Display Modes
  #1  
Old February 15th 09, 06:06 PM posted to rec.bicycles.tech
bfd
external usenet poster
 
Posts: 487
Default Carbon Forks Reliability = paranoia or truth?

The latest Riv Reader #41 is out online:

http://www.rivbike.com/assets/payloa...compressed.pdf

Its not a bad reader. However, what's startled me was the paranoia
about carbon forks. Grant just rails about the negatives of carbon
forks and the failure that will occur in 4 years of use. Here are some
quotes from the Reader:

"I predict that in six years nobody will be making carbon forks
anymore, because nobody will want to ride them."

"There are no drawbacks to wider fork blades, but todayʼs carbon
technology wonʼt allow them to be made safely."

"Steel forks are much safer than carbon ones.Not in the lab, but in
real life. Steel forks can break—in this issue here we show a 30-year
old fork that broke—but will any of todayʼs carbon forks last half as
long, or be safe for a fifth as long? Would you trust a five year old
carbon fork on a 30mph descent, or a thirty year old carbon fork on a
fivemile descent? "

These statements are all on page 1 and 2. Later, on page 44, under
the heading "Some things to think about when youʼre shopping for a
used bike." he states:

"A used carbon fiber bike, one that may have suffered invisibly on its
way to you, is never a good & safe choice. Carbon has some amazing
properties, but its least amazing quality is its ability to fail
catastrophically in circumstances that would barely harm, or maybe not
even harm, a steel bike. If you want carbon, fine, but buy a
new frame, not one somebody else may have already compromised."

I don't know. Back in 1997, I bought a USED carbon fiber bike (Calfee
with Kestrel fork) and have ridden it about 2K miles a year for the
last 11 years. I had my LBS inspect the frameset when I bought it.
Yes, I regularly inspect my frameset for problems. I have no problem
descending 30+mph (routine go faster) and expect both will last years.
I did have the frameset inspected and a new clearcoat put on by the
mfr about 7 years ago.

Is Grant being paranoid or are there legions of carbon forks breaking
and causing death and destruction? Thanks!
Ads
  #2  
Old February 15th 09, 08:13 PM posted to rec.bicycles.tech
Tim McNamara
external usenet poster
 
Posts: 6,945
Default Carbon Forks Reliability = paranoia or truth?

Grant's concern appears to be carbon fiber's failure mode. Notice the
experiment he reports, having a sword fight between a CF fork and a
steel fork. The CF fork dented the steel fork and showed no damage
itself. He was surprised by this (even distressed, given his firm
preference for steel as a frame and fork material as well as the design
parameters he prefers in bikes). Then he tried putting a scratch on the
CF and the fork promptly failed at the next whack. Since scratches
happen easily on a bicycle and carbon fiber has high notch sensitivity,
this is a real problem.

Also, Grant notes that there have been multiple CPSC safety recalls for
CF forks due to failure. We've discussed some of these here in the past.

My opinion is fairly consonant with Grant's on this. I think that CF is
not a suitable material for bike frames, at least the current CF
materials. Future developments may erase my objections. The problems
include low impact tolerance, high notch sensitivity and its
catastrophic failure mode. Metals, on the other hand, have high impact
tolerance, low notch sensitivity and a non-catastophic failure mode.
  #3  
Old February 15th 09, 09:00 PM posted to rec.bicycles.tech
bfd
external usenet poster
 
Posts: 487
Default Carbon Forks Reliability = paranoia or truth?

On Feb 15, 11:13*am, Tim McNamara wrote:
Grant's concern appears to be carbon fiber's failure mode. *Notice the
experiment he reports, having a sword fight between a CF fork and a
steel fork. *The CF fork dented the steel fork and showed no damage
itself. *He was surprised by this (even distressed, given his firm
preference for steel as a frame and fork material as well as the design
parameters he prefers in bikes). *Then he tried putting a scratch on the
CF and the fork promptly failed at the next whack. *Since scratches
happen easily on a bicycle and carbon fiber has high notch sensitivity,
this is a real problem.

I wonder about that test. Grant said he "notched" the carbon fork by
putting a small gouge that wouldn't hurt a steel fork. However, he
doesn't say how big a "notch" he put in the fork and it sounds like
more a "scratch." I can't speak for others, but I inspect my carbon
frameset regularly. In over 20,000 miles, I haven't noticed any
"notches or gouges." If I did, I would get it inspected immediately.
As for frames, my carbon frame had a few scratches in the clearcoat.
Not penetrated the carbon. I just put clear nailpolish and ride.

Also, Grant notes that there have been multiple CPSC safety recalls for
CF forks due to failure. *We've discussed some of these here in the past.

  #4  
Old February 15th 09, 09:58 PM posted to rec.bicycles.tech
D'ohBoy
external usenet poster
 
Posts: 548
Default Carbon Forks Reliability = paranoia or truth?

Uhhh.... I'm confused. What about that 'experiment' proves anything
heretofore unknown about CF? Where is the newly minted cautionary
tale? Anyone who rides more than 50 miles per month who doesn't
inspect his rig regularly is a fool anyway. And my experiences with
even lightweight 1" steerer carbon forks has been quite good. I have
one Alpha Q fork that I have crashed, as in taking a lot of the hit,
not once but twice at 20+ mph (gah!) that I continue to ride. While
both crashes required significant convalescences on my part, the fork
is fine. I have the replacement fork but it is clear (empirically)
that the crashed one is still safe. Ok, yeah, since I have the
replacement, it WOULD be smart to change it out, I agree....

So duud beat the crap outta a carbon fork with a steel one, or tried
to. And the steel fork failed. Okey, waitaminit.... he beat a steel
fork *hard enough to destroy the steel fork* WITH A CARBON FORK and
the carbon fork was *UNDAMAGED*?! And then, because he failed to
prove his point, he availed himself of a hacksaw and notched the
carbon. And lo and behold, it broke when struck! So what he has
proven is that a regularly inspected carbon fork is way better than a
steel one, for most applications.

Someday, if Grant's theories about bike material are challenged, say,
with a wooden fork, and once again, the non-steel fork wins, will he
resort to a comparison of the performance of the two forks after
placing both in the fireplace?

D'ohBoy
  #5  
Old February 16th 09, 12:32 AM posted to rec.bicycles.tech
A Muzi
external usenet poster
 
Posts: 4,551
Default Carbon Forks Reliability = paranoia or truth?

bfd wrote:
On Feb 15, 11:13 am, Tim McNamara wrote:
Grant's concern appears to be carbon fiber's failure mode. Notice the
experiment he reports, having a sword fight between a CF fork and a
steel fork. The CF fork dented the steel fork and showed no damage
itself. He was surprised by this (even distressed, given his firm
preference for steel as a frame and fork material as well as the design
parameters he prefers in bikes). Then he tried putting a scratch on the
CF and the fork promptly failed at the next whack. Since scratches
happen easily on a bicycle and carbon fiber has high notch sensitivity,
this is a real problem.

I wonder about that test. Grant said he "notched" the carbon fork by
putting a small gouge that wouldn't hurt a steel fork. However, he
doesn't say how big a "notch" he put in the fork and it sounds like
more a "scratch." I can't speak for others, but I inspect my carbon
frameset regularly. In over 20,000 miles, I haven't noticed any
"notches or gouges." If I did, I would get it inspected immediately.
As for frames, my carbon frame had a few scratches in the clearcoat.
Not penetrated the carbon. I just put clear nailpolish and ride.

Also, Grant notes that there have been multiple CPSC safety recalls for
CF forks due to failure. We've discussed some of these here in the past.

Didn't see Grant citing any CPSC safety recalls. Have there any
recalls on the arger carbon fork mfrs like Reynolds, True Temper/Alpha
Q, Wound Up and Easton?

My opinion is fairly consonant with Grant's on this. I think that CF is
not a suitable material for bike frames, at least the current CF
materials. Future developments may erase my objections. The problems
include low impact tolerance, high notch sensitivity and its
catastrophic failure mode. Metals, on the other hand, have high impact
tolerance, low notch sensitivity and a non-catastophic failure mode.


Again, I have a Calfee carbon frame that comes with a 25 year
warranty. This frame is very well built. Besides buying it used with
about 2500 miles on it, this frame has been crashed several times, one
causing personal injury to myself, yet the frame was not damaged and
is still going after 11 years of use (14 if you count the previous
owner). Can't speak for the new lightweight framesets coming out of
Taiwan/China, but I don't think carbon is as bad as Grant is trying to
make it.

Btw, my new cross bike is steel (Paul Taylor) and I expect it to last
as long as my Calfee....


I'm not joining a 'carbon fork bad' cult but the second search result of
"CPSC bicycle fork recall" is Reynolds:

http://www.cpsc.gov/cpscpub/prerel/prhtml08/08040.html

(Cervelo came up first of 98,00 hits, Giant TCR third)
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971
  #6  
Old February 16th 09, 06:00 AM posted to rec.bicycles.tech
Ron Ruff
external usenet poster
 
Posts: 1,304
Default Carbon Forks Reliability = paranoia or truth?

Tim McNamara wrote:
Grant's concern appears to be carbon fiber's failure mode. Notice the
experiment he reports, having a sword fight between a CF fork and a
steel fork. The CF fork dented the steel fork and showed no damage
itself. He was surprised by this (even distressed, given his firm
preference for steel as a frame and fork material as well as the design
parameters he prefers in bikes). Then he tried putting a scratch on the
CF and the fork promptly failed at the next whack. Since scratches
happen easily on a bicycle and carbon fiber has high notch sensitivity,
this is a real problem.


If sword fighting with the CF fork didn't damage it enough to cause a
failure, I'm suspicious of this "scratch" he introduced.
  #7  
Old February 16th 09, 07:36 AM posted to rec.bicycles.tech
bfd
external usenet poster
 
Posts: 487
Default Carbon Forks Reliability = paranoia or truth?

On Feb 15, 3:32*pm, A Muzi wrote:
bfd wrote:
On Feb 15, 11:13 am, Tim McNamara wrote:
Grant's concern appears to be carbon fiber's failure mode. *Notice the
experiment he reports, having a sword fight between a CF fork and a
steel fork. *The CF fork dented the steel fork and showed no damage
itself. *He was surprised by this (even distressed, given his firm
preference for steel as a frame and fork material as well as the design
parameters he prefers in bikes). *Then he tried putting a scratch on the
CF and the fork promptly failed at the next whack. *Since scratches
happen easily on a bicycle and carbon fiber has high notch sensitivity,
this is a real problem.


I wonder about that test. Grant said he "notched" the carbon fork by
putting a small gouge that wouldn't hurt a steel fork. However, he
doesn't say how big a "notch" he put in the fork and it sounds like
more a "scratch." *I can't speak for others, but I inspect my carbon
frameset regularly. In over 20,000 miles, I haven't noticed any
"notches or gouges." *If I did, I would get it inspected immediately.
As for frames, my carbon frame had a few scratches in the clearcoat.
Not penetrated the carbon. I just put clear nailpolish and ride.


Also, Grant notes that there have been multiple CPSC safety recalls for
CF forks due to failure. *We've discussed some of these here in the past.


Didn't see Grant citing any CPSC safety recalls. Have there any
recalls on the arger carbon fork mfrs like Reynolds, True Temper/Alpha
Q, Wound Up and Easton?


My opinion is fairly consonant with Grant's on this. *I think that CF is
not a suitable material for bike frames, at least the current CF
materials. *Future developments may erase my objections. *The problems
include low impact tolerance, high notch sensitivity and its
catastrophic failure mode. Metals, on the other hand, have high impact
tolerance, low notch sensitivity and a non-catastophic failure mode.


Again, I have a Calfee carbon frame that comes with a 25 year
warranty. This frame is very well built. Besides buying it used with
about 2500 miles on it, this frame has been crashed several times, one
causing personal injury to myself, yet the frame was not damaged and
is still going after 11 years of use (14 if you count the previous
owner). Can't speak for the new lightweight framesets coming out of
Taiwan/China, but I don't think carbon is as bad as Grant is trying to
make it.


Btw, my new cross bike is steel (Paul Taylor) and I expect it to last
as long as my Calfee....


I'm not joining a 'carbon fork bad' cult but the second search result of
"CPSC bicycle fork recall" *is Reynolds:

http://www.cpsc.gov/cpscpub/prerel/prhtml08/08040.html

(Cervelo came up first of 98,00 hits, Giant TCR third)
--

Thanks. The problematic Reynolds fork is the "UL" version that listed
to weigh 315g. Supposedly, only 330 of these forks had problems.
According to one retailer, all "post-recall" Reynolds UL forks are now
OK. Well, its OK for that vendor to sell it!
  #8  
Old February 16th 09, 07:54 AM posted to rec.bicycles.tech
Dan O
external usenet poster
 
Posts: 6,098
Default Carbon Forks Reliability = paranoia or truth?

On Feb 15, 9:06 am, bfd wrote:
The latest Riv Reader #41 is out online:

http://www.rivbike.com/assets/payloa...compressed.pdf

Its not a bad reader. However, what's startled me was the paranoia
about carbon forks. Grant just rails about the negatives of carbon
forks and the failure that will occur in 4 years of use. Here are some
quotes from the Reader:



"A used carbon fiber bike, one that may have suffered invisibly on its
way to you, is never a good & safe choice... "


Seen tonight on Craigslist:

"I bought this bike in 2008 for $1375. I have ridden it three times,
and found out I don't enjoy riding. It has been stored inside and is
in like new condition. I bought several extras for the bike including
a rear light, water bottle carrier, tool bag with tools, I even have
the original owner's manual with DVD. It is a great bike. Asking $975
OBO... "

(The bike being offered has carbon fiber bits all over it - probably
made as cheaply as possible in order to fill the marketing brochure
with "carbon fiber" buzzwords yet keep the overall cost down.)

Why would anybody with $1000 to spend on a bike try to save a few
hundred by buying a used one from an unaccountable third-party?
(Ooooooo.... he added a water bottle carrier... and it comes with a
DVD! Bonus! :-)

(Okay, so "tools" might be worth something, but probably nothing I
need... )

(Did I mention that I paid $109 for my bike [no DVD included, though]
- and I *love* to ride :-)
  #9  
Old February 16th 09, 08:26 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 2,041
Default Carbon Forks Reliability = paranoia or truth?

On Feb 16, 12:54*am, Dan O wrote:
On Feb 15, 9:06 am, bfd wrote:

The latest Riv Reader #41 is out online:


http://www.rivbike.com/assets/payloa...compressed.pdf


Its not a bad reader. However, what's startled me was the paranoia
about carbon forks. Grant just rails about the negatives of carbon
forks and the failure that will occur in 4 years of use. Here are some
quotes from the Reader:


"A used carbon fiber bike, one that may have suffered invisibly on its
way to you, is never a good & safe choice... "


Seen tonight on Craigslist:

"I bought this bike in 2008 for $1375. I have ridden it three times,
and found out I don't enjoy riding. It has been stored inside and is
in like new condition. I bought several extras for the bike including
a rear light, water bottle carrier, tool bag with tools, I even have
the original owner's manual with DVD. It is a great bike. Asking $975
OBO... "

(The bike being offered has carbon fiber bits all over it - probably
made as cheaply as possible in order to fill the marketing brochure
with "carbon fiber" buzzwords yet keep the overall cost down.)

Why would anybody with $1000 to spend on a bike try to save a few
hundred by buying a used one from an unaccountable third-party?
(Ooooooo.... he added a water bottle carrier... and it comes with a
DVD! *Bonus! :-)

(Okay, so "tools" might be worth something, but probably nothing I
need... )

(Did I mention that I paid $109 for my bike [no DVD included, though]
- and I *love* to ride :-)


$975 might, might be an OK price for a $1375 bike. It did say OBO so
maybe he got it for less than the $975. It is a 2008 new bike.
Supposedly only ridden three times. Or if ridden 30 times it wouldn't
make any difference. Buying used bikes is a very good thing. No
reason in the world to buy new bikes unless you have got to have the
latest and greatest whatever in the bike marketing world. Of my 7
bikes, 4 are used frames. They all work just fine and dandy. The
identical new frame would work no better.
  #10  
Old February 16th 09, 08:34 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 2,041
Default Carbon Forks Reliability = paranoia or truth?

On Feb 16, 1:26*pm, "
wrote:
On Feb 16, 12:54*am, Dan O wrote:





On Feb 15, 9:06 am, bfd wrote:


The latest Riv Reader #41 is out online:


http://www.rivbike.com/assets/payloa...compressed.pdf


Its not a bad reader. However, what's startled me was the paranoia
about carbon forks. Grant just rails about the negatives of carbon
forks and the failure that will occur in 4 years of use. Here are some
quotes from the Reader:


"A used carbon fiber bike, one that may have suffered invisibly on its
way to you, is never a good & safe choice... "


Seen tonight on Craigslist:


"I bought this bike in 2008 for $1375. I have ridden it three times,
and found out I don't enjoy riding. It has been stored inside and is
in like new condition. I bought several extras for the bike including
a rear light, water bottle carrier, tool bag with tools, I even have
the original owner's manual with DVD. It is a great bike. Asking $975
OBO... "


(The bike being offered has carbon fiber bits all over it - probably
made as cheaply as possible in order to fill the marketing brochure
with "carbon fiber" buzzwords yet keep the overall cost down.)


Why would anybody with $1000 to spend on a bike try to save a few
hundred by buying a used one from an unaccountable third-party?
(Ooooooo.... he added a water bottle carrier... and it comes with a
DVD! *Bonus! :-)


(Okay, so "tools" might be worth something, but probably nothing I
need... )


(Did I mention that I paid $109 for my bike [no DVD included, though]
- and I *love* to ride :-)


$975 might, might be an OK price for a $1375 bike. *It did say OBO so
maybe he got it for less than the $975. *It is a 2008 new bike.
Supposedly only ridden three times. *Or if ridden 30 times it wouldn't
make any difference. *Buying used bikes is a very good thing. *No
reason in the world to buy new bikes unless you have got to have the
latest and greatest whatever in the bike marketing world. *Of my 7
bikes, 4 are used frames. *They all work just fine and dandy. *The
identical new frame would work no better.- Hide quoted text -

- Show quoted text -


Forgot to comment on the statement "Why would anybody with $1000 to
spend on a bike try to save a few
hundred by buying a used one from an unaccountable third-party?"
$400, difference between new and asking price, is a healthy amount of
money. I pay attention to $400 amounts. $400/$1375 is 29%. Asking
price of $975 is 71% of new price. That may, may be an OK price for a
"new" used bike. As for the unaccountable third party, so what. You
are buying a bike. You can look at it and tell what condition its
in. Hard to hide things on bikes. You can see the wear and tear its
had, or not had. I've bought several used frames. Just from looking
at them I could easily tell how much they've been ridden and how they
were treated.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Reliability of carbon MTB frames? Dave Techniques 6 August 16th 08 05:14 PM
FS: Carbon forks Darrell Marketplace 0 June 9th 06 07:26 PM
Carbon forks again David E. Belcher UK 7 January 7th 06 10:39 AM
Carbon forks Davidm Australia 7 August 23rd 04 08:21 AM
20" (406) carbon forks? cheg Recumbent Biking 0 July 13th 04 06:32 AM


All times are GMT +1. The time now is 04:26 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.