Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

A very informative discussion of CF as a bike material.

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

A very informative discussion of CF as a bike material.

Old 02-16-21, 08:56 PM
  #51  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 33,731

Bikes: R3 Disc, Haanjo

Mentioned: 343 Post(s)
Tagged: 1 Thread(s)
Quoted: 16017 Post(s)
Liked 4,768 Times in 2,513 Posts
Originally Posted by Koyote View Post
I think anyone should be leery of a person on youtube, earning money from clicks, who passes himself off as an "expert" in a highly technical field without offering anything that we might find on a cv.
Ha! FWIW, looking at his views and subs, this guy isn't making any youtube money, but yes - point taken. I'd add that, personally, when the someone touts "the truth" or that they "tells it like it is," more often then not, they're saying what their audience wants to hear rather than actually being objective.
WhyFi is online now  
Likes For WhyFi:
Old 02-16-21, 10:20 PM
  #52  
Dean V
Senior Member
 
Join Date: Oct 2009
Posts: 2,730
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 984 Post(s)
Likes: 0
Liked 193 Times in 112 Posts
Rather than try and wade through the theory and science which the design engineers have already done.
Just look at the end result.
A light carbon frame is around 700gms and a light aluminium frame is at least 200gms more.
Both will use a carbon fork.
Dean V is offline  
Likes For Dean V:
Old 02-16-21, 10:59 PM
  #53  
woodcraft
Senior Member
 
woodcraft's Avatar
 
Join Date: Apr 2012
Location: Nor Cal
Posts: 5,679
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1669 Post(s)
Likes: 0
Liked 711 Times in 434 Posts
Carbon fiber fabric- somewhat stiffer than your t-shirt.


woodcraft is offline  
Old 02-16-21, 11:00 PM
  #54  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 10,094

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '05 Novara Big Buzz, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T Lab X3

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 1374 Post(s)
Liked 365 Times in 232 Posts
Originally Posted by aplcr0331 View Post
The best video I watched was the one on crank arm length, he did some very cool modeling.
Hey, that’s the one where he references Warren Buffet’s 5 hour live stream treatise on crank arm length from The Berkshire Crank Length Review of Q1 2020. [see vid from 5:36]
chaadster is offline  
Likes For chaadster:
Old 02-16-21, 11:34 PM
  #55  
Carbonfiberboy 
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 17,340

Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004

Mentioned: 106 Post(s)
Tagged: 0 Thread(s)
Quoted: 2895 Post(s)
Liked 807 Times in 605 Posts
Originally Posted by woodcraft View Post
Carbon fiber fabric- somewhat stiffer than your t-shirt.
Which has zip to do with anything. It's the tensile strength and elongation coefficient which are its valuable materials properties.
__________________
Results matter
Carbonfiberboy is offline  
Old 02-17-21, 12:06 AM
  #56  
woodcraft
Senior Member
 
woodcraft's Avatar
 
Join Date: Apr 2012
Location: Nor Cal
Posts: 5,679
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1669 Post(s)
Likes: 0
Liked 711 Times in 434 Posts
Originally Posted by Carbonfiberboy View Post
Which has zip to do with anything. It's the tensile strength and elongation coefficient which are its valuable materials properties.

I didn't make the video, but just watched part of it. He seems to be saying that carbon fiber is stiffer than aluminum,

but it's not really as stiff as they say because they're measuring the CF composite but the resin doesn't add stiffness over the fibers themselves.

This is like saying that sand and gravel are stronger than concrete because the cement doesn't add anything.

My piece of CF is about .3mm, about the same thickness as three layers of aluminum foil. The foil is stiffer.

I think watching this video puts one in danger of being stupider at worst, and more ignorant at best.
woodcraft is offline  
Old 02-17-21, 04:47 AM
  #57  
phrantic09
Fat n slow
 
Join Date: Oct 2013
Location: Saratoga, NY
Posts: 1,580

Bikes: Cervelo R3, Giant Revolt

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 1181 Post(s)
Liked 690 Times in 327 Posts
Watched video, immediately threw both of my carbon bikes in the trash. I can’t believe I thought they were nice bikes!
phrantic09 is offline  
Old 02-17-21, 01:22 PM
  #58  
aplcr0331
IMHOME
 
aplcr0331's Avatar
 
Join Date: Jul 2011
Location: Inland Northwest
Posts: 655

Bikes: 2016 Cannondale SuperSix Evo

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 253 Post(s)
Liked 143 Times in 80 Posts
I watched the full video from the OP finally, and it's not what I was expecting and certainly wasn't bagging on Carbon. I mean he rides carbon bikes anyway. But now I can tell who didn't watch the video by their crybaby comments lol.

Anyway I mentioned before that his other vids are pretty good. That one about crank length and how cool the modeling he used for that one super interesting.

I've shared his video on the Specialized SL7 release hype to all my club friends...that's a great one. My buddy in the UK didn't watch the full video on Titanium. Cause he's a *****, lol. I don't think it's as bad as he thinks.

It's weird how one guy says something you don't like about your preferred bike type or material and you throw a hissy fit?

Oh well, his other videos are interesting and I'll certainly watch those over the lame "paid promotion" GCN videos and that loud mouth Hambini guy.
aplcr0331 is online now  
Likes For aplcr0331:
Old 02-17-21, 01:38 PM
  #59  
bruce19
Senior Member
Thread Starter
 
bruce19's Avatar
 
Join Date: Jul 2006
Location: Lebanon (Liberty Hill), CT
Posts: 7,697

Bikes: CAAD 12, MASI Gran Criterium S, Colnago World Cup CX & Guru steel

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1397 Post(s)
Liked 778 Times in 467 Posts
I am watching his vid on aero positioning and he mentioned that he is a mechanical engineer.
bruce19 is offline  
Likes For bruce19:
Old 02-17-21, 01:43 PM
  #60  
Symox
Senior Member
 
Join Date: Jul 2020
Posts: 220

Bikes: '07 Specialized Roubaix Comp Triple, '12 Gravity Fixie, '21 Liv Rove 4, '06? Giant EB Spirit

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 116 Post(s)
Liked 47 Times in 35 Posts
I skimmed through most of it. The summary I got is builders need to know what they are doing to get the most out of carbon fiber. (That is true of any material btw).

he goes on to rant about generalities of carbon vs aluminum and how they are “rubbish”

I tend to think bike builders have learned a lot over the years in how to work various materials and do their best to get as much performance as they can if for no other reason than competition.

I look at bicycle frames like acoustic guitars. The builder who is skilled can use almost any material to make a great guitar/bike. The choice of material is complex and comes down to cost, performance, durability, consistency and sell ability.

I choose bikes based on which fit and feel the best within my price range. If the frame has a lifetime warranty and the builder a good reputation then I trust they know what they are doing. I don’t really care if it is CF or not.

having said that, in general I’ve found CF bikes to be more expensive and lighted than aluminum and my favorite bikes in my price range have been carbon fiber.
Symox is offline  
Old 02-17-21, 05:16 PM
  #61  
Carbonfiberboy 
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 17,340

Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004

Mentioned: 106 Post(s)
Tagged: 0 Thread(s)
Quoted: 2895 Post(s)
Liked 807 Times in 605 Posts
Originally Posted by woodcraft View Post
I didn't make the video, but just watched part of it. He seems to be saying that carbon fiber is stiffer than aluminum,

but it's not really as stiff as they say because they're measuring the CF composite but the resin doesn't add stiffness over the fibers themselves.

This is like saying that sand and gravel are stronger than concrete because the cement doesn't add anything.

My piece of CF is about .3mm, about the same thickness as three layers of aluminum foil. The foil is stiffer.

I think watching this video puts one in danger of being stupider at worst, and more ignorant at best.
The problem is that you didn't go to engineering school and take materials science and statics. Think about the concepts of tension and compression while holding a toilet paper or paper towel tube in your hands. Try to bend it without collapsing it. The tube is extremely light yet not that easy to bend. Holding it in front of you and trying to bend the ends down, the top is in tension and the bottom is in compression. That's a frame tube, hard to bend, i.e. stiff. Materials which are hard to stretch and compress like carbon fiber/epoxy laminate make a very stiff frame tube. Plus you get to vary the stiffness by the thickness of the laminate. Plus it's not carbon cloth like in the photo. It's "tows" of unidirectional fibers running lengthwise, but at some slight angle to the long dimension of the tube. Thus the tube is also stiff rotationally. Plus you can vary the rotational stiffness vs. the longitudinal stiffness just by changing the angle of the carbon tows. Carbon fiber structural design is not a simple thing, not at all. With metal, the builder is limited to what is made commercially, diameter, wall thickness, and alloy. Not so with carbon/epoxy. Pretty easy to see why carbon is such a popular material.
__________________
Results matter
Carbonfiberboy is offline  
Likes For Carbonfiberboy:
Old 02-17-21, 07:49 PM
  #62  
woodcraft
Senior Member
 
woodcraft's Avatar
 
Join Date: Apr 2012
Location: Nor Cal
Posts: 5,679
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1669 Post(s)
Likes: 0
Liked 711 Times in 434 Posts
Originally Posted by Carbonfiberboy View Post
The problem is that you didn't go to engineering school and take materials science and statics. Think about the concepts of tension and compression while holding a toilet paper or paper towel tube in your hands. Try to bend it without collapsing it. The tube is extremely light yet not that easy to bend. Holding it in front of you and trying to bend the ends down, the top is in tension and the bottom is in compression. That's a frame tube, hard to bend, i.e. stiff. Materials which are hard to stretch and compress like carbon fiber/epoxy laminate make a very stiff frame tube. Plus you get to vary the stiffness by the thickness of the laminate. Plus it's not carbon cloth like in the photo. It's "tows" of unidirectional fibers running lengthwise, but at some slight angle to the long dimension of the tube. Thus the tube is also stiff rotationally. Plus you can vary the rotational stiffness vs. the longitudinal stiffness just by changing the angle of the carbon tows. Carbon fiber structural design is not a simple thing, not at all. With metal, the builder is limited to what is made commercially, diameter, wall thickness, and alloy. Not so with carbon/epoxy. Pretty easy to see why carbon is such a popular material.

Thanks for the tutorial. I do have a working understanding of this stuff in spite of not having gone to engineering school.

The guy in the video seemed to be talking about the stiffness of CF independent of it being made into a structural composite, so I was commenting on that.

Personally, I think carbon fiber bike frames are good, but my current bike count is 1 CF, 4 aluminum, for whatever that's worth.
woodcraft is offline  
Old 02-17-21, 07:59 PM
  #63  
tomato coupe
Senior Member
 
Join Date: Jul 2009
Posts: 1,877

Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 1134 Post(s)
Liked 1,549 Times in 636 Posts
This video seems to be mostly about the host being annoyed that some people are really enamored with carbon fiber as a material, and some now use it in applications where it's cosmetic, not structural. He argues that carbon fiber isn't as stiff as everyone thinks, yet concludes that a carbon frame that's designed to be as stiff as an aluminum frame can be much lighter. Yeah, that's kind of the point dude.
tomato coupe is offline  
Likes For tomato coupe:
Old 02-17-21, 08:00 PM
  #64  
Carbonfiberboy 
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 17,340

Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004

Mentioned: 106 Post(s)
Tagged: 0 Thread(s)
Quoted: 2895 Post(s)
Liked 807 Times in 605 Posts
Originally Posted by woodcraft View Post
Thanks for the tutorial. I do have a working understanding of this stuff in spite of not having gone to engineering school.

The guy in the video seemed to be talking about the stiffness of CF independent of it being made into a structural composite, so I was commenting on that.

Personally, I think carbon fiber bike frames are good, but my current bike count is 1 CF, 4 aluminum, for whatever that's worth.
I have one carbon, 2 alu, 1 steel. I'm glad I did no harm. I worry I come on too strong sometimes.
__________________
Results matter
Carbonfiberboy is offline  
Old 02-18-21, 12:38 AM
  #65  
Seattle Forrest
Senior Member
 
Seattle Forrest's Avatar
 
Join Date: Mar 2010
Location: Seattle, WA
Posts: 21,673
Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 13777 Post(s)
Liked 4,967 Times in 2,807 Posts
Why would anyone go looking for informative on some random dude's youtube?
Seattle Forrest is offline  
Old 02-18-21, 02:27 AM
  #66  
colnago62
Senior Member
 
Join Date: Aug 2014
Posts: 2,269
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 654 Post(s)
Liked 314 Times in 187 Posts
Originally Posted by Seattle Forrest View Post
Why would anyone go looking for informative on some random dude's youtube?
Not much different than coming here.
colnago62 is offline  
Likes For colnago62:
Old 02-18-21, 04:20 AM
  #67  
downhillmaster
Senior Member
 
Join Date: May 2018
Posts: 1,245
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 719 Post(s)
Liked 489 Times in 254 Posts
Originally Posted by colnago62 View Post
Not much different than coming here.
Too perfect.
downhillmaster is offline  
Old 02-18-21, 07:16 AM
  #68  
bruce19
Senior Member
Thread Starter
 
bruce19's Avatar
 
Join Date: Jul 2006
Location: Lebanon (Liberty Hill), CT
Posts: 7,697

Bikes: CAAD 12, MASI Gran Criterium S, Colnago World Cup CX & Guru steel

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1397 Post(s)
Liked 778 Times in 467 Posts
Originally Posted by Carbonfiberboy View Post
I have one carbon, 2 alu, 1 steel. I'm glad I did no harm. I worry I come on too strong sometimes.
What makes the different grades of CF different? And, does it get down to the point where a "lower" level of CF frame is less desirable than say a good AL frame? From a materials science perspective.
bruce19 is offline  
Old 02-18-21, 07:37 AM
  #69  
Trakhak
Senior Member
 
Join Date: Jan 2005
Location: Baltimore, MD
Posts: 2,540
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 789 Post(s)
Liked 488 Times in 300 Posts
Originally Posted by woodcraft View Post
Carbon fiber fabric- somewhat stiffer than your t-shirt.


Anisotropy
Trakhak is online now  
Old 02-18-21, 10:21 AM
  #70  
Carbonfiberboy 
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 17,340

Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004

Mentioned: 106 Post(s)
Tagged: 0 Thread(s)
Quoted: 2895 Post(s)
Liked 807 Times in 605 Posts
Originally Posted by bruce19 View Post
What makes the different grades of CF different? And, does it get down to the point where a "lower" level of CF frame is less desirable than say a good AL frame? From a materials science perspective.
Different grades of CF have different yield strengths and other properties. Better costs more. Stronger CF of course means you can use less of it, and more importantly, less resin, thus a part of the same strength and stiffness is lighter, not much, but lighter. There may be other variables with the resin and layup of which I'm unaware. I'm not an expert on carbon frames! I'm just familiar with the technology and have used it a little.
__________________
Results matter
Carbonfiberboy is offline  
Old 02-22-21, 02:07 PM
  #71  
facorsig
Newbie
 
Join Date: Feb 2015
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I have a degree in materials engineering and a Professional Engineering license in metallurgical engineering. For what it's worth, my road and gravel bikes are titanium frames. There is confusion between stiffness (modulus) and yield or tensile strength. At the end of the day, you ride what you prefer, not something to impress other people.

Fred
facorsig is offline  
Old 02-22-21, 02:09 PM
  #72  
WhyFi
Senior Member
 
WhyFi's Avatar
 
Join Date: Jan 2010
Location: TC, MN
Posts: 33,731

Bikes: R3 Disc, Haanjo

Mentioned: 343 Post(s)
Tagged: 1 Thread(s)
Quoted: 16017 Post(s)
Liked 4,768 Times in 2,513 Posts
Originally Posted by facorsig View Post
I have a degree in materials engineering and a Professional Engineering license in metallurgical engineering. For what it's worth, my road and gravel bikes are titanium frames. There is confusion between stiffness (modulus) and yield or tensile strength. At the end of the day, you ride what you prefer, not something to impress other people.

Fred
Wow, 6 years between registering and your first post - kudos!
WhyFi is online now  
Old 02-22-21, 02:10 PM
  #73  
bruce19
Senior Member
Thread Starter
 
bruce19's Avatar
 
Join Date: Jul 2006
Location: Lebanon (Liberty Hill), CT
Posts: 7,697

Bikes: CAAD 12, MASI Gran Criterium S, Colnago World Cup CX & Guru steel

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1397 Post(s)
Liked 778 Times in 467 Posts
Originally Posted by facorsig View Post
I have a degree in materials engineering and a Professional Engineering license in metallurgical engineering. For what it's worth, my road and gravel bikes are titanium frames. There is confusion between stiffness (modulus) and yield or tensile strength. At the end of the day, you ride what you prefer, not something to impress other people.

Fred
Just curious....what is it about TI that you like?
bruce19 is offline  
Old 02-22-21, 02:16 PM
  #74  
edmguirk
Newbie
 
Join Date: Feb 2021
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I am new to this forum so this is a bit of a hot take but I thought this was all thrashed out back when people were comparing steel, aluminum, and titanium.

I commented on the original video a while ago because he seemed to only be interested in stiffness as if that is the only important thing. Stiffness is irrelevant unless you include strength and weight. A carpet fiber epoxy matrix might not be as stiff as the original fibers but geometry can makeup whatever loss occurred. I can make a bike of any stiffness with any material as long as you don't mind how safe or heavy it is. Sure, CF has directional strength different from steel/alu/tit but all the same arguments still apply. It's always some kind of compromise.

Whatever happened to beryllium?

And, after all, everybody also compromises on style and cost so which one is really best?
edmguirk is offline  
Old 02-22-21, 02:17 PM
  #75  
facorsig
Newbie
 
Join Date: Feb 2015
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
My road rides are endurance rides of 100km and 200km mostly over chip seal roads. I like the vibration attenuation associated with titanium. I do have an aluminum frame bike which I use on my trainer. I have limited riding experience on carbon frame bikes, mostly rentals.

Fred
facorsig is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.