Carbon stem & handle bar

[Christie]

I think looks are the best reason to buy a carbon bar. Second reason would be mass : can score 100 grams. Stiffness gets more difficult : some well designed bars can be stiffer - zipp, enve, etc. Some carbon bars like ITM kswords flex a lot, more than alu. Flex in bars are most noticeble when sprinting or climbing out of thr saddle, so most folks won't actualy notice. Cheaper carbon bars are probably worse than good alu bars. Rather stick to looks and mass.

Stem: looks only reason, no advantage to using carbon for a stem, some oversize carbon stems are very stiff, like the zipp 145 or the Pro one Cavendish used to ride, but they are heavier than good alu stems. My favourite stem is the Zipp service course sl aluminium, in beyond black colour. Stems should have 4 bolts, less than that is unwise.

The damping issue is all "mumbo jumbo", lets just say if you want more damping,, the most effective way would be to put on a double layer of tape, or some handlebar gel pads for under the tape.

[The Guy in Pink]

In the case of my road bars, they just look so good, and they have some very good hand positions

Edited March 3, 2012 by The Guy in Pink

['Dale]

Good points, Christie...

[Johan Bornman]

 

I have ridden enough bikes and handlebar/stem combinations to tell you that there is a HUGE difference in feel.

 

 

Or you can talk to Christie. He's an engineer and will talk not only mambo jumbo figures but will also be able to talk out of years of experience.

 

Just trust me on this one!

 

Oops, look like our trust was misplaced.

[Capricorn]

^{I'm not an engineer, but I cannot see how a small tube the length of a stem or even a handle bar can give any noticable difference in vibration damping. If it does, there is no way a human will be able to tell the difference.Besides, doesn't the front fork absorb all the bumps anyway.}

 

^{There is only one benefit and that is looks.}

 

if not in the weave, then the weft.

 

Very very simplistically: carbon fiber layup is composed of fibers bonded by epoxy, a matrix of materials within tiny discontinuities in the matrix. wheres in an a metal, for all intents and purposes, the material is uniform through out a cross section in any direction.

It's those discontinuities that makes carbon fiber structures that much better at dissipating vibrations. Dont underestimate a human's ability to detect the total aggregated result of micro dampenings.

Less vibrations thru the bars = less fatigue due to vibrations = more endurance.

[Minion]

if not in the weave, then the weft.

 

Very very simplistically: carbon fiber layup is composed of fibers bonded by epoxy, a matrix of materials within tiny discontinuities in the matrix. wheres in an a metal, for all intents and purposes, the material is uniform through out a cross section in any direction.

It's those discontinuities that makes carbon fiber structures that much better at dissipating vibrations. Dont underestimate a human's ability to detect the total aggregated result of micro dampenings.

Less vibrations thru the bars = less fatigue due to vibrations = more endurance.

Isn't this offset by the fact that carbon fibre is much stiffer than aluminium, which increases the overall amount of vibration transmitted?

[Berry]

^{I'm not an engineer, but I cannot see how a small tube the length of a stem or even a handle bar can give any noticable difference in vibration damping. If it does, there is no way a human will be able to tell the difference.Besides, doesn't the front fork absorb all the bumps anyway.}

 

^{There is only one benefit and that is looks.}

 

you sound like my wife carbon is the way to go

[gummibear]

In the case of my road bars, they just look so good, and they have some very good hand positions

 

Those are awesome bars.....but all i see is $$$$$$$$$$$$

[The Guy in Pink]

Those are awesome bars.....but all i see is $$$$$$$$$$$$

That's why I gotta live in a Tent in The Congo most of the year ... gotta earn some $$$ to pay for the stuff.

I lived in the first tent for six months, I now got a room built under the same roof.

[Caerus]

That's why I gotta live in a Tent in The Congo most of the year ... gotta earn some $$$ to pay for the stuff.

I lived in the first tent for six months, I now got a room built under the same roof.

Where do you ride for most of the year?

Edited March 4, 2012 by Caerus

[The Guy in Pink]

Where do you ride for most of the year?

I've got a bike here in the Congo, I get out 4 or 5 days a week for about 90 minutes.

I am on the bike at about 4:30 am and ride in the dark.

As there is no one up at that time its the best time from a security position .

I did go out in the evenings but our security guys vetoed it..

 

At home I ride in the Soutpansberg, or the roads around them. ( Think Kremetart)

Edited March 4, 2012 by The Guy in Pink

[gummibear]

Where in the Congo are you?i heard there has been a morse bomb blast in Brazzaville.

[The Guy in Pink]

Where in the Congo are you?i heard there has been a morse bomb blast in Brazzaville.

Eastern DRC Congo, near the Borders with Rwanda and Burundi . In the mountains at over 2000 metre above sea level.

So although we are almost on the equator I have 2 jerseys on now.

[Capricorn]

Isn't this offset by the fact that carbon fibre is much stiffer than aluminium, which increases the overall amount of vibration transmitted?

 

strangely enough, no. microvibrations are more easily damped, leading to an overall feel of being more damped. I've tried reading up on this a bit more, but that's generally the simply answer: the tech answer is pretty hardcore physics. I understand the apparent contradiction, because the modulus of elasticity of carbon fiber is pretty damn high compared to many metals. the Aramid composites exhibit even more stiffness, but those do not have the same level of damping.

 

i think it has to with the multidirectional weave. the vibration still requires a solid path way for distribution. in a multiweave carbon fibre matrix, micro vibrations take a multitude of directions and thus dissipate non uniformly. This is the only difference compared to metal where despite the crystal matrix that metals are comprised of, the boundaries are solid. In a carbon fibre matrix, i'm pretty sure the epoxy cement holding the matrix together does not permeate around every single strand of CF (despite the ultra high pressures the lay ups are baked at) ,and the CFs are hollow. Thus on a macro and microscopic level, the interfiber and trans-fibre transmission of vibrations is not via ultra stiff solids, leading to the cumulative damping properties I surmised earlier.

[Capricorn]

been trying to think of an analogy, but a simple one does not come to mind. One that does, but using a temperature analogy, is aerogel. It's the drastically reduced flow of air through it's porous structure that makes it such a fantastic insulator.

[Capricorn]

seems i might be on the right track as it seems a they use vibration modelling to determine the effectiveness of carbon composite depending on the method of fabrication and the epoxy used.

 

here's an extract of a technical paper on damping properties of fiber reinforced composites for stayed cables (long span bridge applications).