[ANNOUNCE] New bicycle shopping guide web site

Mike Jacoubowsky wrote in message ...
My apology if this is off topic.

I just launched a new bicycle web site that has the following goals:

- Help people shopping for a new bicycle
- Give basic mechanic skills that will be helpful to keep your bicycles
in
good shape over time

Here are the current sections I cover:

-The basics
-Major types of bicycles
-Choosing the right bicycle
-After you buy

I hope you like it. Your feedback will be appreciated.

http://bikes.jump-gate.com/

from http://bikes.jump-gate.com/basics.shtml-

"The frame of a bicycle is one of the most important component we will look
at. It defines the comportment of the bicycle on the road. The frame being
a
great amount of the overall material making the bicycle, it also affects
its
weight quite noticeably. Some lower-cost bicycles still use steel tubing.
You should avoid this type of frame as much as possible. Nowadays, most
frames are made of various alloys. The most current one is aluminum. When
the first aluminum bicycles were put on market, many exhibited soldering
problem and were subject to break under heavy usage. This is not a concern
anymore . You can safely buy an aluminum frame in all confidence. Aluminum
as become the common frame material for mid to high end bicycles. At the
end
of the spectrum, we are seeing carbon frames. Carbon frames have many
advantages. They are very strong (resistant), and at the same time, more
flexible than aluminum tubes. What does it implies? While they are more
robust, the small flexion they allow creates a frame that is more
comfortable to ride. That is because the high energy found in small
vibrations coming from the road imperfections is dissipated by these
flexion, instead of being fully transmitted to the cyclist. What is good
for
the comfort of the cyclist is unfortunately bad for the energy efficiency
of
the bicycle. As the cyclist pushes on the pedals, the frame absorbs a
percentage of the cyclist energy. That energy will never get transmitted in
the transmission system of the bicycle. Many high-end race bicycles uses
carbon forks to provide some sort of high-frequency shocks absorption, to
the detriment of some performance. This is a far lighter way to provide
shock absorption than using real shock absorbers, which would be
unpractical
on race bicycles. "

#1: Aluminum is not the "most current" frame material. It's been around
for ages.

#2: You cannot "safely" by a frame made of aluminum, any more than you can
any other material. It's not the material, it's how it's used that makes
the difference. There are aluminum frames that will outlive the owner, and
there are aluminum frames whose lack of a warranty is for very good reason.

#3: Carbon frame are "...unfortunately bad for the energy efficeincy of
the
bicycle" and carbon forks "..provide some sort of high-frequency shocks
absorption, to the detriment of some performance." ??? Somebody better
have a conversation with the Grand Tour racers about this one; apparently,
they could all ride a lot faster if they ditched their carbon frames &
forks?

#4: Reading through the site, the type of grammatical errors make it seem
that it's not original, but has been translated from a different language
(and not always very well).

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where you
discover, I think, that a "road bike" is different from a "racing bike"
because it has a taller head tube and, most likely, a sloping top tube.

I could swear I've seen this all before, but don't remember where.
Whatever
the case, it's very unfortunate that people might read some of the
information and believe it. As is often the case, there's some practical
info that makes sense, and perhaps just enough of it to make someone
believe
the rest of it.

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


I've heard three water bottles are required on fleecy frames to dampen
oscillatory motion about the gravitational exception tubulerosity which
exists in all traditional frame design. A good reason for using recumbents.
You can die of thirst.

Trevor

Contrary to what you assumed, the totality of the content found on this
site was written by me. Nothing was taken from somewhere else. It is all
based on my own experience only.

Marc: I was probably a bit too strident in my comments, and apologize that
I came across a bit too strongly.

Unfortunately, yes, there are still a lot of grammatical errors. I am
working on it. English is not my native language. That may explain it. I
will do my best to better polish the text.

Which explains the sense of familiarity I had when reading it. It reads a
bit like a translation from French, but much cleaner than what Google would
have done (which can sometimes be quite amusing).

I think one red flag that went up was the lack of personaliztion; instead,
the first thing you see are the Google ads on the side of the page, and get
the idea that somebody might have thrown up a page with the sole intent of
generating advertising revenue. I think a brief "about me" section when
somebody comes to the page would be a good thing.

#1: Aluminum is not the "most current" frame material. It's been
around for ages.

To my point of view, aluminum is the most currently sold frame material
for
the general public type of bikes. Carbon is close-by, but still a notch on
the high-end market.

Here the language thing is causing a bit of trouble. "Most current" would
typically mean that it's the most-recent type of material used. "Most
common" would be the choice to describe something that's used on most bikes.

#3: Carbon frame are "...unfortunately bad for the energy efficeincy
of the bicycle" and carbon forks "..provide some sort of
high-frequency shocks absorption, to the detriment of some
performance." ??? Somebody better have a conversation with the Grand
Tour racers about this one; apparently, they could all ride a lot
faster if they ditched their carbon frames & forks?

Carbon does flex a bit more than an equivalent-made aluminum frame or fork
I believe (I use a racer bike that has a carbon fork). It does not make
carbon a bad material for bikes. If I said that, please let me know so I
can rectify. I may have forgot to emphasizes that structural flexion is
not
the only factor. Weight is also playing big for the Grand Tour racers like
you said. Any other important factor I should add? Let me know.

That was probably the section that caused the most trouble for me. Carbon
fiber works so well in bicycles because it's incredibly light, very strong
and doesn't carry vibration the way metals do. That gives it a different
"feel" but it has nothing to do with efficiency. In fact, no material
presently used in bicycle frames flexes in a way that it actually absorbs
energy, at least not on a scale that's meaningful. What does happen is that
a particular design might flex in a manner that's annoying or might cause
handling difficulties. But even that is more a function of design than it
is the material used.

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where
you discover, I think, that a "road bike" is different from a "racing
bike" because it has a taller head tube and, most likely, a sloping
top tube.

This site is for casual cyclist at first. I did not go in detail on that
section I agree. I can add more details you may provide on what
differentiate race bikes from road bikes.

The issue is at least partly definitional. "Road bike" is an
all-encompassing term that generally includes any bike with downturned (or
"drop") handlebars. Within the "Road bike" category are various
sub-categories, such as-

Criterium bike (very steep angles, twitchy handling, feels really fast but
often delivers a rather punishing ride, probably a result of the very short
wheelbase and position over the rear wheel)

Classic road bike (more moderate angles & wheelbase, and suitable for
day-after-day racing and often the best choice for high-performance sport
riding, such as doing centuries. This category represents the largest
number of road bikes sold, and for good reason. The same things that a
racer wants are what many others do- high-performance, light weight, and
reasonable comfort).

"Comfort" road bike (a relatively new category, designed to allow for a
higher handlebar relative to the saddle, and often a shorter distance from
seat to handlebars. Sometimes these bikes will even have extra brake levers
across the top of the handlebars, to allow braking when you're in a more
upright position).

Touring bike (longer wheelbase to distribute the load over the wheels better
and enhance stability & comfort, plus components & frame chosen for
durability over light weight).

CycloCross (something between a touring and road bike)

etc etc

Again, sorry that I came across a bit too strongly.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
IMBA, BikesBelong, NBDA member

"Marc B" wrote in message
...
Mike, thanks for your critical feedback. I am taking your remarks
seriously
and will look into these issues. First off, let me just precise that this
site is targeting people with little experience in bikes that want some
help to make better decisions as they shop. This of course is not an
excuse
for inaccuracies found on the site, which I should of course correct. This
site will probably look very pale for experts, and it is not my intention
to target these people as such... They know as good as me (or better) how
to pick a good bike! That being said, read my comments below...

Regards.

"Mike Jacoubowsky" wrote in
om:


#1: Aluminum is not the "most current" frame material. It's been
around for ages.

To my point of view, aluminum is the most currently sold frame material
for
the general public type of bikes. Carbon is close-by, but still a notch on
the high-end market.

#2: You cannot "safely" by a frame made of aluminum, any more than
you can any other material. It's not the material, it's how it's used
that makes the difference. There are aluminum frames that will
outlive the owner, and there are aluminum frames whose lack of a
warranty is for very good reason.

I was referring to older generations, back in time, when aluminum was the
new big thing, but even then, you may have a point.


#3: Carbon frame are "...unfortunately bad for the energy efficeincy
of the bicycle" and carbon forks "..provide some sort of
high-frequency shocks absorption, to the detriment of some
performance." ??? Somebody better have a conversation with the Grand
Tour racers about this one; apparently, they could all ride a lot
faster if they ditched their carbon frames & forks?

Carbon does flex a bit more than an equivalent-made aluminum frame or fork
I believe (I use a racer bike that has a carbon fork). It does not make
carbon a bad material for bikes. If I said that, please let me know so I
can rectify. I may have forgot to emphasizes that structural flexion is
not
the only factor. Weight is also playing big for the Grand Tour racers like
you said. Any other important factor I should add? Let me know.

#4: Reading through the site, the type of grammatical errors make it
seem that it's not original, but has been translated from a different
language (and not always very well).

Unfortunately, yes, there are still a lot of grammatical errors. I am
working on it. English is not my native language. That may explain it. I
will do my best to better polish the text.

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where
you discover, I think, that a "road bike" is different from a "racing
bike" because it has a taller head tube and, most likely, a sloping
top tube.

This site is for casual cyclist at first. I did not go in detail on that
section I agree. I can add more details you may provide on what
differentiate race bikes from road bikes.

I could swear I've seen this all before, but don't remember where.
Whatever the case, it's very unfortunate that people might read some
of the information and believe it. As is often the case, there's some
practical info that makes sense, and perhaps just enough of it to make
someone believe the rest of it.

Contrary to what you assumed, the totality of the content found on this
site was written by me. Nothing was taken from somewhere else. It is all
based on my own experience only.


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



Thanks for your valuable inputs mike. If you would like to suggest text
corrections, I will gladly consider your suggestions.

Regards.
Marc B.

Contrary to what you assumed, the totality of the content found on this
site was written by me. Nothing was taken from somewhere else. It is all
based on my own experience only.

Marc: I was probably a bit too strident in my comments, and apologize that
I came across a bit too strongly.

Unfortunately, yes, there are still a lot of grammatical errors. I am
working on it. English is not my native language. That may explain it. I
will do my best to better polish the text.

Which explains the sense of familiarity I had when reading it. It reads a
bit like a translation from French, but much cleaner than what Google would
have done (which can sometimes be quite amusing).

I think one red flag that went up was the lack of personaliztion; instead,
the first thing you see are the Google ads on the side of the page, and get
the idea that somebody might have thrown up a page with the sole intent of
generating advertising revenue. I think a brief "about me" section when
somebody comes to the page would be a good thing.

#1: Aluminum is not the "most current" frame material. It's been
around for ages.

To my point of view, aluminum is the most currently sold frame material
for
the general public type of bikes. Carbon is close-by, but still a notch on
the high-end market.

Here the language thing is causing a bit of trouble. "Most current" would
typically mean that it's the most-recent type of material used. "Most
common" would be the choice to describe something that's used on most bikes.

#3: Carbon frame are "...unfortunately bad for the energy efficeincy
of the bicycle" and carbon forks "..provide some sort of
high-frequency shocks absorption, to the detriment of some
performance." ??? Somebody better have a conversation with the Grand
Tour racers about this one; apparently, they could all ride a lot
faster if they ditched their carbon frames & forks?

Carbon does flex a bit more than an equivalent-made aluminum frame or fork
I believe (I use a racer bike that has a carbon fork). It does not make
carbon a bad material for bikes. If I said that, please let me know so I
can rectify. I may have forgot to emphasizes that structural flexion is
not
the only factor. Weight is also playing big for the Grand Tour racers like
you said. Any other important factor I should add? Let me know.

That was probably the section that caused the most trouble for me. Carbon
fiber works so well in bicycles because it's incredibly light, very strong
and doesn't carry vibration the way metals do. That gives it a different
"feel" but it has nothing to do with efficiency. In fact, no material
presently used in bicycle frames flexes in a way that it actually absorbs
energy, at least not on a scale that's meaningful. What does happen is that
a particular design might flex in a manner that's annoying or might cause
handling difficulties. But even that is more a function of design than it
is the material used.

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where
you discover, I think, that a "road bike" is different from a "racing
bike" because it has a taller head tube and, most likely, a sloping
top tube.

This site is for casual cyclist at first. I did not go in detail on that
section I agree. I can add more details you may provide on what
differentiate race bikes from road bikes.

The issue is at least partly definitional. "Road bike" is an
all-encompassing term that generally includes any bike with downturned (or
"drop") handlebars. Within the "Road bike" category are various
sub-categories, such as-

Criterium bike (very steep angles, twitchy handling, feels really fast but
often delivers a rather punishing ride, probably a result of the very short
wheelbase and position over the rear wheel)

Classic road bike (more moderate angles & wheelbase, and suitable for
day-after-day racing and often the best choice for high-performance sport
riding, such as doing centuries. This category represents the largest
number of road bikes sold, and for good reason. The same things that a
racer wants are what many others do- high-performance, light weight, and
reasonable comfort).

"Comfort" road bike (a relatively new category, designed to allow for a
higher handlebar relative to the saddle, and often a shorter distance from
seat to handlebars. Sometimes these bikes will even have extra brake levers
across the top of the handlebars, to allow braking when you're in a more
upright position).

Touring bike (longer wheelbase to distribute the load over the wheels better
and enhance stability & comfort, plus components & frame chosen for
durability over light weight).

CycloCross (something between a touring and road bike)

etc etc

Again, sorry that I came across a bit too strongly.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
IMBA, BikesBelong, NBDA member

"Marc B" wrote in message
...
Mike, thanks for your critical feedback. I am taking your remarks
seriously
and will look into these issues. First off, let me just precise that this
site is targeting people with little experience in bikes that want some
help to make better decisions as they shop. This of course is not an
excuse
for inaccuracies found on the site, which I should of course correct. This
site will probably look very pale for experts, and it is not my intention
to target these people as such... They know as good as me (or better) how
to pick a good bike! That being said, read my comments below...

Regards.

"Mike Jacoubowsky" wrote in
om:


#1: Aluminum is not the "most current" frame material. It's been
around for ages.

To my point of view, aluminum is the most currently sold frame material
for
the general public type of bikes. Carbon is close-by, but still a notch on
the high-end market.

#2: You cannot "safely" by a frame made of aluminum, any more than
you can any other material. It's not the material, it's how it's used
that makes the difference. There are aluminum frames that will
outlive the owner, and there are aluminum frames whose lack of a
warranty is for very good reason.

I was referring to older generations, back in time, when aluminum was the
new big thing, but even then, you may have a point.


#3: Carbon frame are "...unfortunately bad for the energy efficeincy
of the bicycle" and carbon forks "..provide some sort of
high-frequency shocks absorption, to the detriment of some
performance." ??? Somebody better have a conversation with the Grand
Tour racers about this one; apparently, they could all ride a lot
faster if they ditched their carbon frames & forks?

Carbon does flex a bit more than an equivalent-made aluminum frame or fork
I believe (I use a racer bike that has a carbon fork). It does not make
carbon a bad material for bikes. If I said that, please let me know so I
can rectify. I may have forgot to emphasizes that structural flexion is
not
the only factor. Weight is also playing big for the Grand Tour racers like
you said. Any other important factor I should add? Let me know.

#4: Reading through the site, the type of grammatical errors make it
seem that it's not original, but has been translated from a different
language (and not always very well).

Unfortunately, yes, there are still a lot of grammatical errors. I am
working on it. English is not my native language. That may explain it. I
will do my best to better polish the text.

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where
you discover, I think, that a "road bike" is different from a "racing
bike" because it has a taller head tube and, most likely, a sloping
top tube.

This site is for casual cyclist at first. I did not go in detail on that
section I agree. I can add more details you may provide on what
differentiate race bikes from road bikes.

I could swear I've seen this all before, but don't remember where.
Whatever the case, it's very unfortunate that people might read some
of the information and believe it. As is often the case, there's some
practical info that makes sense, and perhaps just enough of it to make
someone believe the rest of it.

Contrary to what you assumed, the totality of the content found on this
site was written by me. Nothing was taken from somewhere else. It is all
based on my own experience only.


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



Thanks for your valuable inputs mike. If you would like to suggest text
corrections, I will gladly consider your suggestions.

Regards.
Marc B.

"Mike Jacoubowsky/Chain Reaction Bicycles"
wrote in m:

Contrary to what you assumed, the totality of the content found on
this site was written by me. Nothing was taken from somewhere else.
It is all based on my own experience only.

Marc: I was probably a bit too strident in my comments, and apologize
that I came across a bit too strongly.

Thanks for your comprehension Mike, I appreciate.

Unfortunately, yes, there are still a lot of grammatical errors. I am
working on it. English is not my native language. That may explain
it. I will do my best to better polish the text.

Which explains the sense of familiarity I had when reading it. It
reads a bit like a translation from French, but much cleaner than what
Google would have done (which can sometimes be quite amusing).

I know what you mean. Google is quite poor, as many computer-based
translators, to well translate the initial meaning twist of a text.

I think one red flag that went up was the lack of personaliztion;
instead, the first thing you see are the Google ads on the side of the
page, and get the idea that somebody might have thrown up a page with
the sole intent of generating advertising revenue. I think a brief
"about me" section when somebody comes to the page would be a good
thing.

There is actually an "About the author" section on the site. The text I
put there is very sort and does not say much. I will try to add some
more info to it.


#1: Aluminum is not the "most current" frame material. It's been
around for ages.

To my point of view, aluminum is the most currently sold frame
material for
the general public type of bikes. Carbon is close-by, but still a
notch on the high-end market.

Here the language thing is causing a bit of trouble. "Most current"
would typically mean that it's the most-recent type of material used.
"Most common" would be the choice to describe something that's used on
most bikes.

Granted. I had the feeling this word was not appropriate seing your
comments. I will use "common" instead.

#3: Carbon frame are "...unfortunately bad for the energy
efficeincy of the bicycle" and carbon forks "..provide some sort of
high-frequency shocks absorption, to the detriment of some
performance." ??? Somebody better have a conversation with the
Grand Tour racers about this one; apparently, they could all ride a
lot faster if they ditched their carbon frames & forks?

Carbon does flex a bit more than an equivalent-made aluminum frame or
fork I believe (I use a racer bike that has a carbon fork). It does
not make carbon a bad material for bikes. If I said that, please let
me know so I can rectify. I may have forgot to emphasizes that
structural flexion is not
the only factor. Weight is also playing big for the Grand Tour racers
like you said. Any other important factor I should add? Let me know.

That was probably the section that caused the most trouble for me.
Carbon fiber works so well in bicycles because it's incredibly light,
very strong and doesn't carry vibration the way metals do. That gives
it a different "feel" but it has nothing to do with efficiency. In
fact, no material presently used in bicycle frames flexes in a way
that it actually absorbs energy, at least not on a scale that's
meaningful. What does happen is that a particular design might flex
in a manner that's annoying or might cause handling difficulties. But
even that is more a function of design than it is the material used.

Yes. Actually, we kind of were saying similar things from a different
angle perhaps. The fact that carbon allows some flexing is probably what
makes it "absorb" some of the vibration. An infinitely strong material,
based on the little I know, would transfer all vibration without any
loss.

Here is my theory (which may be totally wrong). The key thing here is
"fiber". The carbon fibers will be indeed very strong if you try to
elongate it for example. However, if you apply pressure sideways of the
fibers, then it will probably allow quite some flexion before it breaks.
So the spring or shock absorber propriety it displays is indeed
dependent of the structure, i.e., it depends from where the vibration
shock comes from and how it is aligned with the carbon fibers.

Still, it remains a very strong and, most importantly, light material
for high-end bikes. When I say that it "flexes", I guess I refer to the
overall frame structure... not a small region of the frame that you
would zoom on. For instance, when I put my race bike (aluminum frame in
this case) on my Cateye 1000 platform, as I push on the pedals, I can
easily see the torsion of the lower part of the frame, the bottom
bracket I think it is called in English, where the cranks links on the
frame. This torsion is there because, even if the frame is strong, it
flexes under the force I apply to the pedal, which does a lever effect
on the bottom bracket and the frame. It is easier to see on such a setup
as the front fork of the bike is clamped firmly on the platform,
limiting global bike movements.

From my experience with a few bikes, I think that it is an unavoidable
compromise situation. The lighter you want to make the bike, the more
you will lose in overall stiffness of the frame and other parts.
However, in the end, weight probably brings way more benefits than the
little flexing you add to the bike. Going from steel tubing, to aluminum
and carbon, we can feel that performance progression with the weight
reduction it brings.

It is very probable that the flexing is more a question of the design
than the material indeed. Perhaps I should remove this point from my
text altogether, in lack of having sufficient data on the carbon vs
other materials proprieties. This is an interesting discussion thought.
If anyone else in this forum has expertise with these material
proprieties, please let us know.

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where
you discover, I think, that a "road bike" is different from a
"racing bike" because it has a taller head tube and, most likely, a
sloping top tube.

This site is for casual cyclist at first. I did not go in detail on
that section I agree. I can add more details you may provide on what
differentiate race bikes from road bikes.

The issue is at least partly definitional. "Road bike" is an
all-encompassing term that generally includes any bike with downturned
(or "drop") handlebars. Within the "Road bike" category are various
sub-categories, such as-

Criterium bike (very steep angles, twitchy handling, feels really fast
but often delivers a rather punishing ride, probably a result of the
very short wheelbase and position over the rear wheel)

Classic road bike (more moderate angles & wheelbase, and suitable for
day-after-day racing and often the best choice for high-performance
sport riding, such as doing centuries. This category represents the
largest number of road bikes sold, and for good reason. The same
things that a racer wants are what many others do- high-performance,
light weight, and reasonable comfort).

"Comfort" road bike (a relatively new category, designed to allow for
a higher handlebar relative to the saddle, and often a shorter
distance from seat to handlebars. Sometimes these bikes will even
have extra brake levers across the top of the handlebars, to allow
braking when you're in a more upright position).

Touring bike (longer wheelbase to distribute the load over the wheels
better and enhance stability & comfort, plus components & frame chosen
for durability over light weight).

CycloCross (something between a touring and road bike)

etc etc


Interesting. I will try to incorporate these comments into the related
sections. Thanks.


Again, sorry that I came across a bit too strongly.

That is okay :-) I do appreciate your inputs.
Regards.

MarcB

"Mike Jacoubowsky/Chain Reaction Bicycles"
wrote in m:

Contrary to what you assumed, the totality of the content found on
this site was written by me. Nothing was taken from somewhere else.
It is all based on my own experience only.

Marc: I was probably a bit too strident in my comments, and apologize
that I came across a bit too strongly.

Thanks for your comprehension Mike, I appreciate.

Unfortunately, yes, there are still a lot of grammatical errors. I am
working on it. English is not my native language. That may explain
it. I will do my best to better polish the text.

Which explains the sense of familiarity I had when reading it. It
reads a bit like a translation from French, but much cleaner than what
Google would have done (which can sometimes be quite amusing).

I know what you mean. Google is quite poor, as many computer-based
translators, to well translate the initial meaning twist of a text.

I think one red flag that went up was the lack of personaliztion;
instead, the first thing you see are the Google ads on the side of the
page, and get the idea that somebody might have thrown up a page with
the sole intent of generating advertising revenue. I think a brief
"about me" section when somebody comes to the page would be a good
thing.

There is actually an "About the author" section on the site. The text I
put there is very sort and does not say much. I will try to add some
more info to it.


#1: Aluminum is not the "most current" frame material. It's been
around for ages.

To my point of view, aluminum is the most currently sold frame
material for
the general public type of bikes. Carbon is close-by, but still a
notch on the high-end market.

Here the language thing is causing a bit of trouble. "Most current"
would typically mean that it's the most-recent type of material used.
"Most common" would be the choice to describe something that's used on
most bikes.

Granted. I had the feeling this word was not appropriate seing your
comments. I will use "common" instead.

#3: Carbon frame are "...unfortunately bad for the energy
efficeincy of the bicycle" and carbon forks "..provide some sort of
high-frequency shocks absorption, to the detriment of some
performance." ??? Somebody better have a conversation with the
Grand Tour racers about this one; apparently, they could all ride a
lot faster if they ditched their carbon frames & forks?

Carbon does flex a bit more than an equivalent-made aluminum frame or
fork I believe (I use a racer bike that has a carbon fork). It does
not make carbon a bad material for bikes. If I said that, please let
me know so I can rectify. I may have forgot to emphasizes that
structural flexion is not
the only factor. Weight is also playing big for the Grand Tour racers
like you said. Any other important factor I should add? Let me know.

That was probably the section that caused the most trouble for me.
Carbon fiber works so well in bicycles because it's incredibly light,
very strong and doesn't carry vibration the way metals do. That gives
it a different "feel" but it has nothing to do with efficiency. In
fact, no material presently used in bicycle frames flexes in a way
that it actually absorbs energy, at least not on a scale that's
meaningful. What does happen is that a particular design might flex
in a manner that's annoying or might cause handling difficulties. But
even that is more a function of design than it is the material used.

Yes. Actually, we kind of were saying similar things from a different
angle perhaps. The fact that carbon allows some flexing is probably what
makes it "absorb" some of the vibration. An infinitely strong material,
based on the little I know, would transfer all vibration without any
loss.

Here is my theory (which may be totally wrong). The key thing here is
"fiber". The carbon fibers will be indeed very strong if you try to
elongate it for example. However, if you apply pressure sideways of the
fibers, then it will probably allow quite some flexion before it breaks.
So the spring or shock absorber propriety it displays is indeed
dependent of the structure, i.e., it depends from where the vibration
shock comes from and how it is aligned with the carbon fibers.

Still, it remains a very strong and, most importantly, light material
for high-end bikes. When I say that it "flexes", I guess I refer to the
overall frame structure... not a small region of the frame that you
would zoom on. For instance, when I put my race bike (aluminum frame in
this case) on my Cateye 1000 platform, as I push on the pedals, I can
easily see the torsion of the lower part of the frame, the bottom
bracket I think it is called in English, where the cranks links on the
frame. This torsion is there because, even if the frame is strong, it
flexes under the force I apply to the pedal, which does a lever effect
on the bottom bracket and the frame. It is easier to see on such a setup
as the front fork of the bike is clamped firmly on the platform,
limiting global bike movements.

From my experience with a few bikes, I think that it is an unavoidable
compromise situation. The lighter you want to make the bike, the more
you will lose in overall stiffness of the frame and other parts.
However, in the end, weight probably brings way more benefits than the
little flexing you add to the bike. Going from steel tubing, to aluminum
and carbon, we can feel that performance progression with the weight
reduction it brings.

It is very probable that the flexing is more a question of the design
than the material indeed. Perhaps I should remove this point from my
text altogether, in lack of having sufficient data on the carbon vs
other materials proprieties. This is an interesting discussion thought.
If anyone else in this forum has expertise with these material
proprieties, please let us know.

Next, check out http://bikes.jump-gate.com/types_bikes.shtml, where
you discover, I think, that a "road bike" is different from a
"racing bike" because it has a taller head tube and, most likely, a
sloping top tube.

This site is for casual cyclist at first. I did not go in detail on
that section I agree. I can add more details you may provide on what
differentiate race bikes from road bikes.

The issue is at least partly definitional. "Road bike" is an
all-encompassing term that generally includes any bike with downturned
(or "drop") handlebars. Within the "Road bike" category are various
sub-categories, such as-

Criterium bike (very steep angles, twitchy handling, feels really fast
but often delivers a rather punishing ride, probably a result of the
very short wheelbase and position over the rear wheel)

Classic road bike (more moderate angles & wheelbase, and suitable for
day-after-day racing and often the best choice for high-performance
sport riding, such as doing centuries. This category represents the
largest number of road bikes sold, and for good reason. The same
things that a racer wants are what many others do- high-performance,
light weight, and reasonable comfort).

"Comfort" road bike (a relatively new category, designed to allow for
a higher handlebar relative to the saddle, and often a shorter
distance from seat to handlebars. Sometimes these bikes will even
have extra brake levers across the top of the handlebars, to allow
braking when you're in a more upright position).

Touring bike (longer wheelbase to distribute the load over the wheels
better and enhance stability & comfort, plus components & frame chosen
for durability over light weight).

CycloCross (something between a touring and road bike)

etc etc


Interesting. I will try to incorporate these comments into the related
sections. Thanks.


Again, sorry that I came across a bit too strongly.

That is okay :-) I do appreciate your inputs.
Regards.

MarcB