Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Carbon seatpost strength

Notices
General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Carbon seatpost strength

Old 12-13-05, 08:41 PM
  #26  
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Posts: 16,681

Bikes: 8 bikes - one for each day of the week!

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Welcome back, by the way.
Brian is offline  
Old 12-14-05, 09:14 AM
  #27  
Senior Member
 
Join Date: Oct 2004
Posts: 5,250
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 7 Times in 7 Posts
Carbon posts, handlebars, and forks do very well under routine stress. But, tighten a seat clamp too much, tighten a stem bolt too much, hit a pothole at high speed...carbon fails, and it fails instantly.

But, carbon is light, cool, and your neighbor can't afford it. Aren't those things more important than your health or life?
alanbikehouston is offline  
Old 12-14-05, 10:18 AM
  #28  
Senior Member
Thread Starter
 
Join Date: Feb 2004
Location: Cleveland, OH
Posts: 2,304

Bikes: 2004 Trek 4600 SS, 2016 Cannondale Cujo 2 SS

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by Machka
The snapped forks I saw broke under a guy who wasn't very big ... and who was riding downhill on a very smooth road. He was hospitalized.


That's two carbon failures (my seatpost and his forks) I've seen in less than a year ... and enough for me to consider carbon as a non-viable material for a bicycle.
The seemingly sporadic faliure of carbon fiber has got to be either misuse or manufacturing defects, not a flaw with the material itself.
trekkie820 is offline  
Old 12-14-05, 11:04 AM
  #29  
Senior Member
 
Join Date: Feb 2002
Posts: 1,175
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 117 Post(s)
Liked 70 Times in 50 Posts
Think of it this way--carbon is a material you're not supposed to a.) Clamp, and b.) Grease. What sense does it make to use it for a part whose basic function means wrapping a clamp around it and will only stop creaking in many frames if you smear grease on it? Carbon seatposts are an example of consumer stupidity and manufacturer dishonesty.
Feldman is offline  
Old 12-14-05, 01:45 PM
  #30  
Senior Member
 
Join Date: Sep 2005
Posts: 190
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I just replaced my seatpost on my Trek 7.5 FX disc with a carbon one. The carbon didn't really feel any lighter even though it's about 6 inches shorter. It does look better though.
jonbth is offline  
Old 12-14-05, 01:56 PM
  #31  
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Posts: 16,681

Bikes: 8 bikes - one for each day of the week!

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Originally Posted by trekkie820
The seemingly sporadic faliure of carbon fiber has got to be either misuse or manufacturing defects, not a flaw with the material itself.
But you don't really get to pick which. That's the fun of it.
Brian is offline  
Old 12-14-05, 02:55 PM
  #32  
Up on the Down Side
 
CyLowe97's Avatar
 
Join Date: Mar 2005
Location: Chicago(ish)
Posts: 6,334
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 5 Times in 4 Posts
How about a carbon/aluminum post? My Felt has a 'carbon' seatpost, but also says 6061 on it... is this just an aluminum post wrapped in carbon to look 'blingy?'
CyLowe97 is offline  
Old 12-14-05, 03:08 PM
  #33  
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Posts: 16,681

Bikes: 8 bikes - one for each day of the week!

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
CR-wrapped Alu is a good thing. Wasn't that how the early bars were done? And a lot of CF forks? That seems to be an ok combination. Take the best qualities of both materials, and combine them into one strong and light part that offers damping.
Brian is offline  
Old 12-14-05, 03:13 PM
  #34  
Somewhere in CA
 
Join Date: Jul 2004
Posts: 816
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked 4 Times in 1 Post
Im 5'11 155lbs. broke a very expensive selcof. was replaced under warranty. its sitting on my desk now. do i dare put it back in I'm pretty sure I will......
Jim Bonnet is offline  
Old 12-14-05, 03:26 PM
  #35  
Senior Member
 
Brian's Avatar
 
Join Date: Nov 2004
Location: Between the mountains and the lake.
Posts: 16,681

Bikes: 8 bikes - one for each day of the week!

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Originally Posted by Jim Bonnet
Im 5'11 155lbs. broke a very expensive selcof. was replaced under warranty. its sitting on my desk now. do i dare put it back in I'm pretty sure I will......
Core sample candidate. What would Darwin say?
Brian is offline  
Old 12-14-05, 03:41 PM
  #36  
You know you want to.
 
Eatadonut's Avatar
 
Join Date: Jun 2005
Location: Norman, Oklahoma
Posts: 1,894

Bikes: Pinarello Prince, 1980's 531 steel fixie commuter, FrankenMTB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by MERTON
you don't know about carbon wheels? where have you been?
i think she's been out of town
__________________
Weather today: Hot. Humid. Potholes.
Eatadonut is offline  

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.