To carbon fork or not to carbon fork...

On Oct 17, 5:43*pm, AMuzi wrote:
On 10/17/2012 10:56 AM, Duane Hébert wrote:

On 10/17/2012 10:17 AM, landotter wrote:
On Oct 13, 9:05 pm, piscesboy wrote:
I'm considering getting a road bike and considering
whether to get the "standard" model or the same model
with a carbon fork for $100 or so more. It's supposed to
make for a more stable ride on rougher roads, but what
are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****.
Get a carbon
fork if it comes with a bike you like, or if you're racing
and it'll
help you drop some grams. Otherwise, it doesn't matter.
For comfort,
large tires and cockpit details are far more important.

You don't think that a carbon fork would be more comfortable
than an aluminum fork on the same frame with 125 psi 700 x
23c tires?

I don't.
They are probably both adequately strong and of the same
geometry as far as handling but I bet you could not tell
them apart if similarly painted.

I agree with Andrew. While I don't own a carbon fork bike, I've
ridden several of my friends' carbon bikes. I don't think carbon has
any magic effect on comfort, and AFAIK neither do the friends who
bought those bikes.

The first couple of guys to buy carbon seem to have done it before
claims of magic comfort came out - at least, I don't recall such
claims in the 1990s - and they never mentioned any such comfort. One
woman even bought a Zertz-equipped carbon bike a few years ago, and
she specifically said she couldn't tell any comfort difference between
her steel bikes.

But to get technical, as we do here from time to time: What would
cause the difference? As far as I know, once fit is dialed in, the
main "comfort" effect (i.e. reduction in road shock) comes from
flexibility in the vertical direction. There's no way a typical
carbon fork flexes significantly more in the vertical than a typical
steel or aluminum fork. Any difference is far, far smaller than the
deflection of the tire.

There might be a small effect from the reduction in fork mass that
comes from using carbon fiber. That is, once the fork mass has been
accelerated upward by a bump, a massier fork will transmit more force
to the rider's hands than a fork with less mass. But the mass of the
fork is a small percentage of the total mass being moved upward, so
any difference due directly to fork mass reduction should be small, I
think. And it occurs to me, the smoothest riding cars and motorcycles
tend to have larger sprung masses and smaller unsprung masses; for
smooth ride, it's considered more beneficial to reduce the upward
motion of the sprung mass, rather than to lessen that mass and thus
allow more upward motion. (We could discuss this, I suppose.)

In any case, I think the claims for carbon forks put us back into "The
princess and the pea" territory.

You want comfort? Fit a fatter tire - if your fork will allow it, that
is. A great many carbon forks won't allow fatter tires. Today's
weird fashion is carbon plus near-zero tire clearance. And there's no
accounting for fashion. Or for its sales pitches.

- Frank Krygowski

On 10/17/2012 8:38 PM, Frank Krygowski wrote:
On Oct 17, 5:43 pm, AMuzi wrote:
On 10/17/2012 10:56 AM, Duane Hébert wrote:

On 10/17/2012 10:17 AM, landotter wrote:
On Oct 13, 9:05 pm, piscesboy wrote:
I'm considering getting a road bike and considering
whether to get the "standard" model or the same model
with a carbon fork for $100 or so more. It's supposed to
make for a more stable ride on rougher roads, but what
are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****.
Get a carbon
fork if it comes with a bike you like, or if you're racing
and it'll
help you drop some grams. Otherwise, it doesn't matter.
For comfort,
large tires and cockpit details are far more important.

You don't think that a carbon fork would be more comfortable
than an aluminum fork on the same frame with 125 psi 700 x
23c tires?

I don't.
They are probably both adequately strong and of the same
geometry as far as handling but I bet you could not tell
them apart if similarly painted.

I agree with Andrew. While I don't own a carbon fork bike, I've
ridden several of my friends' carbon bikes. I don't think carbon has
any magic effect on comfort, and AFAIK neither do the friends who
bought those bikes.

The first couple of guys to buy carbon seem to have done it before
claims of magic comfort came out - at least, I don't recall such
claims in the 1990s - and they never mentioned any such comfort. One
woman even bought a Zertz-equipped carbon bike a few years ago, and
she specifically said she couldn't tell any comfort difference between
her steel bikes.

But to get technical, as we do here from time to time: What would
cause the difference? As far as I know, once fit is dialed in, the
main "comfort" effect (i.e. reduction in road shock) comes from
flexibility in the vertical direction. There's no way a typical
carbon fork flexes significantly more in the vertical than a typical
steel or aluminum fork. Any difference is far, far smaller than the
deflection of the tire.

There might be a small effect from the reduction in fork mass that
comes from using carbon fiber. That is, once the fork mass has been
accelerated upward by a bump, a massier fork will transmit more force
to the rider's hands than a fork with less mass. But the mass of the
fork is a small percentage of the total mass being moved upward, so
any difference due directly to fork mass reduction should be small, I
think. And it occurs to me, the smoothest riding cars and motorcycles
tend to have larger sprung masses and smaller unsprung masses; for
smooth ride, it's considered more beneficial to reduce the upward
motion of the sprung mass, rather than to lessen that mass and thus
allow more upward motion. (We could discuss this, I suppose.)

In any case, I think the claims for carbon forks put us back into "The
princess and the pea" territory.

You want comfort? Fit a fatter tire - if your fork will allow it, that
is. A great many carbon forks won't allow fatter tires. Today's
weird fashion is carbon plus near-zero tire clearance. And there's no
accounting for fashion. Or for its sales pitches.

- Frank Krygowski


I recently did a floor pump rebuild. Customer wanted
assurance that he could get his preferred 130psi from it so
I did just that on my own front wheel, which was nearby.

I sure did notice that running errands an hour later!

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Thursday, October 18, 2012 12:38:13 PM UTC+11, Frank Krygowski wrote:
On Oct 17, 5:43*pm, AMuzi wrote:

On 10/17/2012 10:56 AM, Duane Hébert wrote:



On 10/17/2012 10:17 AM, landotter wrote:

On Oct 13, 9:05 pm, piscesboy wrote:

I'm considering getting a road bike and considering

whether to get the "standard" model or the same model

with a carbon fork for $100 or so more. It's supposed to

make for a more stable ride on rougher roads, but what

are your conclusions/reviews/recommendations on this claim?



Did the bike shop make this claim? Because it's bull****.

Get a carbon

fork if it comes with a bike you like, or if you're racing

and it'll

help you drop some grams. Otherwise, it doesn't matter.

For comfort,

large tires and cockpit details are far more important.



You don't think that a carbon fork would be more comfortable

than an aluminum fork on the same frame with 125 psi 700 x

23c tires?



I don't.

They are probably both adequately strong and of the same

geometry as far as handling but I bet you could not tell

them apart if similarly painted.



I agree with Andrew. While I don't own a carbon fork bike, I've

ridden several of my friends' carbon bikes. I don't think carbon has

any magic effect on comfort, and AFAIK neither do the friends who

bought those bikes.



The first couple of guys to buy carbon seem to have done it before

claims of magic comfort came out - at least, I don't recall such

claims in the 1990s - and they never mentioned any such comfort. One

woman even bought a Zertz-equipped carbon bike a few years ago, and

she specifically said she couldn't tell any comfort difference between

her steel bikes.

I do not disbelieve those who complained about earlier all Al frames being harsh. They had a bicycle (or more likely several bicycles) before their Al bike, and consequently had something to compare too. It was because of these complaints that manufacturers have taken measures to improve comfort.

Not all Al bikes are (were) harsh though, and certainly steel and CRFP can be made to be every bit as harsh or more if you want.

Wheel design can also have some effect on perceived comfort.

A mate and I swapped bikes while warming up before a race not long ago. We both concluded that my steel frame felt stiffer than his Ti frame, though they are about the same size, have a CFRP fork, oversize tubes, hard saddle - and even though his wheels are (presumably) very rigid Zipp 404s. When we swapped back, he mentioned it first, but I was already thinking it. Materials can make perceivable differences in feel - even when outside dimensions look quite similar.

Of course, my steel frame weighs about 500 g more and cost less than half as much ;-)

But to get technical, as we do here from time to time: What would

cause the difference? As far as I know, once fit is dialed in, the

main "comfort" effect (i.e. reduction in road shock) comes from

flexibility in the vertical direction. There's no way a typical

carbon fork flexes significantly more in the vertical than a typical

steel or aluminum fork. Any difference is far, far smaller than the

deflection of the tire.



There might be a small effect from the reduction in fork mass that

comes from using carbon fiber. That is, once the fork mass has been

accelerated upward by a bump, a massier fork will transmit more force

to the rider's hands than a fork with less mass. But the mass of the

"Massier"? What was wrong with heavier, or "a fork with more mass"?

fork is a small percentage of the total mass being moved upward, so

any difference due directly to fork mass reduction should be small, I

think. And it occurs to me, the smoothest riding cars and motorcycles

tend to have larger sprung masses and smaller unsprung masses; for

smooth ride, it's considered more beneficial to reduce the upward

motion of the sprung mass, rather than to lessen that mass and thus

allow more upward motion. (We could discuss this, I suppose.)

I guess one question is where do you consider the spring? A 23 mm tyre at 125 psi with little load on it doesn't deflect much.

Perhaps the spring is in the wrists and arms. Having a lighter front end is easier for these "suspension components" to absorb the movement and shock..

One other thing is that some of the movement in a fork as you ride over bumps is backward and forward (rather than up and down). This may contribute to the road "buzz" you feel. CFRP will possibly damp that buzz more than metal.

In any case, I think the claims for carbon forks put us back into "The

princess and the pea" territory.



You want comfort? Fit a fatter tire - if your fork will allow it, that

is. A great many carbon forks won't allow fatter tires.

OTOH, if you look it is not so difficult to find CFRP forks that do have adequate tyre clearance and eyelets for mudguards. A quick search yields...

http://www.ribblecycles.co.uk/sp/roa...es/DEDAFORW200

http://www.kinesisbikes.co.uk/products/forks/road/dc07

http://www.kinesisbikes.co.uk/products/forks/road/dc21

The cyclocross world offers more range.

--
JS

On 10/17/2012 08:32 PM, John B. wrote:
On Wed, 17 Oct 2012 11:56:11 -0400, Duane Hébert
wrote:

On 10/17/2012 10:17 AM, landotter wrote:
On Oct 13, 9:05 pm, piscesboy wrote:
I'm considering getting a road bike and considering whether to get the "standard" model or the same model with a carbon fork for $100 or so more. It's supposed to make for a more stable ride on rougher roads, but what are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****. Get a carbon
fork if it comes with a bike you like, or if you're racing and it'll
help you drop some grams. Otherwise, it doesn't matter. For comfort,
large tires and cockpit details are far more important.


You don't think that a carbon fork would be more comfortable than an
aluminum fork on the same frame with 125 psi 700 x 23c tires?

I can't say for the aluminum but certainly my Giant TCR2 with a carbon
fork and 300C 23 tires (or smaller) didn't feel any different, at
least nothing that could be attributed to the fork, then a light steel
bike road bike with the usual curved steel fork.

So if there is a difference it is not memorable enough that one can
notice it riding the same route on different days.

I'm not saying that there is a difference. Only that most of the bike
shops seem to be saying that.

On Wednesday, October 17, 2012 9:54:15 PM UTC-4, AMuzi wrote:
On 10/17/2012 8:38 PM, Frank Krygowski wrote:

On Oct 17, 5:43 pm, AMuzi wrote:

On 10/17/2012 10:56 AM, Duane H�bert wrote:



On 10/17/2012 10:17 AM, landotter wrote:

On Oct 13, 9:05 pm, piscesboy wrote:

I'm considering getting a road bike and considering

whether to get the "standard" model or the same model

with a carbon fork for $100 or so more. It's supposed to

make for a more stable ride on rougher roads, but what

are your conclusions/reviews/recommendations on this claim?



Did the bike shop make this claim? Because it's bull****.

Get a carbon

fork if it comes with a bike you like, or if you're racing

and it'll

help you drop some grams. Otherwise, it doesn't matter.

For comfort,

large tires and cockpit details are far more important.



You don't think that a carbon fork would be more comfortable

than an aluminum fork on the same frame with 125 psi 700 x

23c tires?



I don't.

They are probably both adequately strong and of the same

geometry as far as handling but I bet you could not tell

them apart if similarly painted.



I agree with Andrew. While I don't own a carbon fork bike, I've

ridden several of my friends' carbon bikes. I don't think carbon has

any magic effect on comfort, and AFAIK neither do the friends who

bought those bikes.



The first couple of guys to buy carbon seem to have done it before

claims of magic comfort came out - at least, I don't recall such

claims in the 1990s - and they never mentioned any such comfort. One

woman even bought a Zertz-equipped carbon bike a few years ago, and

she specifically said she couldn't tell any comfort difference between

her steel bikes.



But to get technical, as we do here from time to time: What would

cause the difference? As far as I know, once fit is dialed in, the

main "comfort" effect (i.e. reduction in road shock) comes from

flexibility in the vertical direction. There's no way a typical

carbon fork flexes significantly more in the vertical than a typical

steel or aluminum fork. Any difference is far, far smaller than the

deflection of the tire.



There might be a small effect from the reduction in fork mass that

comes from using carbon fiber. That is, once the fork mass has been

accelerated upward by a bump, a massier fork will transmit more force

to the rider's hands than a fork with less mass. But the mass of the

fork is a small percentage of the total mass being moved upward, so

any difference due directly to fork mass reduction should be small, I

think. And it occurs to me, the smoothest riding cars and motorcycles

tend to have larger sprung masses and smaller unsprung masses; for

smooth ride, it's considered more beneficial to reduce the upward

motion of the sprung mass, rather than to lessen that mass and thus

allow more upward motion. (We could discuss this, I suppose.)



In any case, I think the claims for carbon forks put us back into "The

princess and the pea" territory.



You want comfort? Fit a fatter tire - if your fork will allow it, that

is. A great many carbon forks won't allow fatter tires. Today's

weird fashion is carbon plus near-zero tire clearance. And there's no

accounting for fashion. Or for its sales pitches.



- Frank Krygowski





I recently did a floor pump rebuild. Customer wanted

assurance that he could get his preferred 130psi from it so

I did just that on my own front wheel, which was nearby.



I sure did notice that running errands an hour later!

I'm not surprised. The difference in vertical deflection of a tire varies a _lot_ with tire pressure.

The 3 speed bike I built last year gets used only for short utility rides, seldom more than five miles. It's got 32mm tires on it, and I don't bother to pump them until they get quite soft, like 50 psi. The cushy low pressure ride is kind of nice, but then I get worried about pinch flats. 130 psi would rattle out my tooth fillings, if the tires didn't blow off first.

- Frank Krygowski

On Wednesday, October 17, 2012 10:37:52 PM UTC-4, James wrote:
On Thursday, October 18, 2012 12:38:13 PM UTC+11, Frank Krygowski wrote:

There might be a small effect from the reduction in fork mass that



comes from using carbon fiber. That is, once the fork mass has been



accelerated upward by a bump, a massier fork will transmit more force



to the rider's hands than a fork with less mass. But the mass of the



"Massier"? What was wrong with heavier, or "a fork with more mass"?

Well, there's the extra typing (although that's moot if someone complains). There's also the fact that "heavier" implies more weight, but strictly speaking it's the mass, not the weight, that's responsible for the effect I was describing. I spent many years teaching engineering mechanics & physics, so I tend to pay attention to the difference.,




fork is a small percentage of the total mass being moved upward, so



any difference due directly to fork mass reduction should be small, I



think. And it occurs to me, the smoothest riding cars and motorcycles



tend to have larger sprung masses and smaller unsprung masses; for



smooth ride, it's considered more beneficial to reduce the upward



motion of the sprung mass, rather than to lessen that mass and thus



allow more upward motion. (We could discuss this, I suppose.)



I guess one question is where do you consider the spring? A 23 mm tyre at 125 psi with little load on it doesn't deflect much.

True! That's why they're the first thing to change for rough road use.


Perhaps the spring is in the wrists and arms. Having a lighter front end is easier for these "suspension components" to absorb the movement and shock.

If you're after comfort (in the sense of less perceived shock) I think you want to stop the shock _before_ it gets to your wrists and arms.




One other thing is that some of the movement in a fork as you ride over bumps is backward and forward (rather than up and down). This may contribute to the road "buzz" you feel. CFRP will possibly damp that buzz more than metal.



In any case, I think the claims for carbon forks put us back into "The



princess and the pea" territory.







You want comfort? Fit a fatter tire - if your fork will allow it, that



is. A great many carbon forks won't allow fatter tires.



OTOH, if you look it is not so difficult to find CFRP forks that do have adequate tyre clearance and eyelets for mudguards. A quick search yields....



http://www.ribblecycles.co.uk/sp/roa...es/DEDAFORW200



http://www.kinesisbikes.co.uk/products/forks/road/dc07



http://www.kinesisbikes.co.uk/products/forks/road/dc21



The cyclocross world offers more range.

It's good there are some out there. It would be better if there were more, and if they all specified enough dimensions so one could be sure what would fit.

- Frank Krygowski

On Oct 18, 4:44*pm, wrote:
On Wednesday, October 17, 2012 9:54:15 PM UTC-4, AMuzi wrote:
On 10/17/2012 8:38 PM, Frank Krygowski wrote:

On Oct 17, 5:43 pm, AMuzi wrote:

On 10/17/2012 10:56 AM, Duane H bert wrote:

On 10/17/2012 10:17 AM, landotter wrote:

On Oct 13, 9:05 pm, piscesboy wrote:

I'm considering getting a road bike and considering

whether to get the "standard" model or the same model

with a carbon fork for $100 or so more. It's supposed to

make for a more stable ride on rougher roads, but what

are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****.

Get a carbon

fork if it comes with a bike you like, or if you're racing

and it'll

help you drop some grams. Otherwise, it doesn't matter.

For comfort,

large tires and cockpit details are far more important.

You don't think that a carbon fork would be more comfortable

than an aluminum fork on the same frame with 125 psi 700 x

23c tires?

I don't.

They are probably both adequately strong and of the same

geometry as far as handling but I bet you could not tell

them apart if similarly painted.

I agree with Andrew. *While I don't own a carbon fork bike, I've

ridden several of my friends' carbon bikes. *I don't think carbon has

any magic effect on comfort, and AFAIK neither do the friends who

bought those bikes.

The first couple of guys to buy carbon seem to have done it before

claims of magic comfort came out - at least, I don't recall such

claims in the 1990s - and they never mentioned any such comfort. *One

woman even bought a Zertz-equipped carbon bike a few years ago, and

she specifically said she couldn't tell any comfort difference between

her steel bikes.

But to get technical, as we do here from time to time: *What would

cause the difference? *As far as I know, once fit is dialed in, the

main "comfort" effect (i.e. reduction in road shock) comes from

flexibility in the vertical direction. *There's no way a typical

carbon fork flexes significantly more in the vertical than a typical

steel or aluminum fork. *Any difference is far, far smaller than the

deflection of the tire.

There might be a small effect from the reduction in fork mass that

comes from using carbon fiber. *That is, once the fork mass has been

accelerated upward by a bump, a massier fork will transmit more force

to the rider's hands than a fork with less mass. *But the mass of the

fork is a small percentage of the total mass being moved upward, so

any difference due directly to fork mass reduction should be small, I

think. *And it occurs to me, the smoothest riding cars and motorcycles

tend to have larger sprung masses and smaller unsprung masses; for

smooth ride, it's considered more beneficial to reduce the upward

motion of the sprung mass, rather than to lessen that mass and thus

allow more upward motion. *(We could discuss this, I suppose.)

In any case, I think the claims for carbon forks put us back into "The

princess and the pea" territory.

You want comfort? Fit a fatter tire - if your fork will allow it, that

is. *A great many carbon forks won't allow fatter tires. *Today's

weird fashion is carbon plus near-zero tire clearance. *And there's no

accounting for fashion. *Or for its sales pitches.

- Frank Krygowski

I recently did a floor pump rebuild. Customer wanted

assurance that he could get his preferred 130psi from it so

I did just that on my own front wheel, which was nearby.

I sure did notice that running errands an hour later!

I'm not surprised. *The difference in vertical deflection of a tire varies a _lot_ with tire pressure.

The 3 speed bike I built last year gets used only for short utility rides, seldom more than five miles. *It's got 32mm tires on it, and I don't bother to pump them until they get quite soft, like 50 psi. *The cushy low pressure ride is kind of nice, but then I get worried about pinch flats. *130 psi would rattle out my tooth fillings, if the tires didn't blow off first.

- Frank Krygowski

Just make sure you spit out any amalgam fillings.

Frank Krygowski wrote:
On Oct 17, 5:43 pm, AMuzi wrote:
On 10/17/2012 10:56 AM, Duane Hébert wrote:

On 10/17/2012 10:17 AM, landotter wrote:
On Oct 13, 9:05 pm, piscesboy wrote:
I'm considering getting a road bike and considering
whether to get the "standard" model or the same model
with a carbon fork for $100 or so more. It's supposed to
make for a more stable ride on rougher roads, but what
are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****.
Get a carbon
fork if it comes with a bike you like, or if you're racing
and it'll
help you drop some grams. Otherwise, it doesn't matter.
For comfort,
large tires and cockpit details are far more important.

You don't think that a carbon fork would be more comfortable
than an aluminum fork on the same frame with 125 psi 700 x
23c tires?

I don't.
They are probably both adequately strong and of the same
geometry as far as handling but I bet you could not tell
them apart if similarly painted.

I agree with Andrew. While I don't own a carbon fork bike, I've
ridden several of my friends' carbon bikes. I don't think carbon has
any magic effect on comfort, and AFAIK neither do the friends who
bought those bikes.

The first couple of guys to buy carbon seem to have done it before
claims of magic comfort came out - at least, I don't recall such
claims in the 1990s - and they never mentioned any such comfort. One
woman even bought a Zertz-equipped carbon bike a few years ago, and
she specifically said she couldn't tell any comfort difference between
her steel bikes.

But to get technical, as we do here from time to time: What would
cause the difference? As far as I know, once fit is dialed in, the
main "comfort" effect (i.e. reduction in road shock) comes from
flexibility in the vertical direction. There's no way a typical
carbon fork flexes significantly more in the vertical than a typical
steel or aluminum fork. Any difference is far, far smaller than the
deflection of the tire.

There might be a small effect from the reduction in fork mass that
comes from using carbon fiber. That is, once the fork mass has been
accelerated upward by a bump, a massier fork will transmit more force
to the rider's hands than a fork with less mass. But the mass of the
fork is a small percentage of the total mass being moved upward, so
any difference due directly to fork mass reduction should be small, I
think. And it occurs to me, the smoothest riding cars and motorcycles
tend to have larger sprung masses and smaller unsprung masses; for
smooth ride, it's considered more beneficial to reduce the upward
motion of the sprung mass, rather than to lessen that mass and thus
allow more upward motion. (We could discuss this, I suppose.)

In any case, I think the claims for carbon forks put us back into "The
princess and the pea" territory.

You want comfort? Fit a fatter tire - if your fork will allow it, that
is. A great many carbon forks won't allow fatter tires. Today's
weird fashion is carbon plus near-zero tire clearance. And there's no
accounting for fashion. Or for its sales pitches.

-
Frank Krygowski,
There may be differences in damping as well.
Kerry

On Oct 18, 3:37*am, James wrote:
On Thursday, October 18, 2012 12:38:13 PM UTC+11, Frank Krygowski wrote:
On Oct 17, 5:43*pm, AMuzi wrote:

On 10/17/2012 10:56 AM, Duane Hébert wrote:

On 10/17/2012 10:17 AM, landotter wrote:

On Oct 13, 9:05 pm, piscesboy wrote:

I'm considering getting a road bike and considering

whether to get the "standard" model or the same model

with a carbon fork for $100 or so more. It's supposed to

make for a more stable ride on rougher roads, but what

are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****.

Get a carbon

fork if it comes with a bike you like, or if you're racing

and it'll

help you drop some grams. Otherwise, it doesn't matter.

For comfort,

large tires and cockpit details are far more important.

You don't think that a carbon fork would be more comfortable

than an aluminum fork on the same frame with 125 psi 700 x

23c tires?

I don't.

They are probably both adequately strong and of the same

geometry as far as handling but I bet you could not tell

them apart if similarly painted.

I agree with Andrew. *While I don't own a carbon fork bike, I've

ridden several of my friends' carbon bikes. *I don't think carbon has

any magic effect on comfort, and AFAIK neither do the friends who

bought those bikes.

The first couple of guys to buy carbon seem to have done it before

claims of magic comfort came out - at least, I don't recall such

claims in the 1990s - and they never mentioned any such comfort. *One

woman even bought a Zertz-equipped carbon bike a few years ago, and

she specifically said she couldn't tell any comfort difference between

her steel bikes.

I do not disbelieve those who complained about earlier all Al frames being harsh. *They had a bicycle (or more likely several bicycles) before their Al bike, and consequently had something to compare too. *It was because of these complaints that manufacturers have taken measures to improve comfort.

Not all Al bikes are (were) harsh though, and certainly steel and CRFP can be made to be every bit as harsh or more if you want.

Wheel design can also have some effect on perceived comfort.

A mate and I swapped bikes while warming up before a race not long ago. *We both concluded that my steel frame felt stiffer than his Ti frame, though they are about the same size, have a CFRP fork, oversize tubes, hard saddle - and even though his wheels are (presumably) very rigid Zipp 404s. *When we swapped back, he mentioned it first, but I was already thinking it. *Materials can make perceivable differences in feel - even when outside dimensions look quite similar.

Of course, my steel frame weighs about 500 g more and cost less than half as much ;-)









But to get technical, as we do here from time to time: *What would

cause the difference? *As far as I know, once fit is dialed in, the

main "comfort" effect (i.e. reduction in road shock) comes from

flexibility in the vertical direction. *There's no way a typical

carbon fork flexes significantly more in the vertical than a typical

steel or aluminum fork. *Any difference is far, far smaller than the

deflection of the tire.

There might be a small effect from the reduction in fork mass that

comes from using carbon fiber. *That is, once the fork mass has been

accelerated upward by a bump, a massier fork will transmit more force

to the rider's hands than a fork with less mass. *But the mass of the

"Massier"? *What was wrong with heavier, or "a fork with more mass"?

fork is a small percentage of the total mass being moved upward, so

any difference due directly to fork mass reduction should be small, I

think. *And it occurs to me, the smoothest riding cars and motorcycles

tend to have larger sprung masses and smaller unsprung masses; for

smooth ride, it's considered more beneficial to reduce the upward

motion of the sprung mass, rather than to lessen that mass and thus

allow more upward motion. *(We could discuss this, I suppose.)

I guess one question is where do you consider the spring? *A 23 mm tyre at 125 psi with little load on it doesn't deflect much.

Perhaps the spring is in the wrists and arms. *Having a lighter front end is easier for these "suspension components" to absorb the movement and shock.

One other thing is that some of the movement in a fork as you ride over bumps is backward and forward (rather than up and down). *This may contribute to the road "buzz" you feel. *CFRP will possibly damp that buzz more than metal.

In any case, I think the claims for carbon forks put us back into "The

princess and the pea" territory.

You want comfort? Fit a fatter tire - if your fork will allow it, that

is. *A great many carbon forks won't allow fatter tires.

OTOH, if you look it is not so difficult to find CFRP forks that do have adequate tyre clearance and eyelets for mudguards. *A quick search yields....

http://www.ribblecycles.co.uk/sp/roa...lack-Rain-Wint...
"
RIBBLE Price Online price, a saving of 20% on Ribble prices.
1 1/8" ITS £109.95 £87.96 out of stock "

They didn't last long. You do realise that in NW England it was, and
maybe still is, for racing men to ride 120 miles in winter between
8:30 and 3:30 with either 2 cafe stops or a prolonged lunch stop? If
that fork survives simple falls it is no surprise they are popular at
the price. I like the fork I have on my racing bike, SL blades, with
the spokes tensioned to provide minimal shock transmission to the
rider at 20mph over some local cobbles.

One may improve the ride comfort using any forks by modifying
spokeline and tension but an overly stiff fork will overstress the
wheel, possibly leading to early failure, or at the minimum a lesser
accuracy in tracking and speed wobbles (although these mostly
originate from the rear wheel, a low spoke count or thin gauge, as may
be expected on a front wheel, will also encourage it).

http://www.kinesisbikes.co.uk/products/forks/road/dc07

http://www.kinesisbikes.co.uk/products/forks/road/dc21

The cyclocross world offers more range.

--
JS

On Oct 18, 2:13*pm, Duane Hébert wrote:
On 10/17/2012 08:32 PM, John B. wrote:









On Wed, 17 Oct 2012 11:56:11 -0400, Duane Hébert
wrote:

On 10/17/2012 10:17 AM, landotter wrote:
On Oct 13, 9:05 pm, piscesboy wrote:
I'm considering getting a road bike and considering whether to get the "standard" model or the same model with a carbon fork for $100 or so more. It's supposed to make for a more stable ride on rougher roads, but what are your conclusions/reviews/recommendations on this claim?

Did the bike shop make this claim? Because it's bull****. Get a carbon
fork if it comes with a bike you like, or if you're racing and it'll
help you drop some grams. Otherwise, it doesn't matter. For comfort,
large tires and cockpit details are far more important.

You don't think that a carbon fork would be more comfortable than an
aluminum fork on the same frame with 125 psi 700 x 23c tires?

I can't say for the aluminum but certainly my Giant TCR2 with a carbon
fork and 300C 23 tires (or smaller) didn't feel any different, at
least nothing that could be attributed to the fork, then a light steel
bike road bike with the usual curved steel fork.

So if there is a difference it is not memorable enough that one can
notice it riding the same route on different days.

I'm not saying that there is a difference. *Only that most of the bike
shops seem to be saying that.

Well, if you are doing the rounds, perhaps you can get them to be
specific about differences.