Which of these seatposts for a Tarmac SL4?

Considering getting the Specialized S-works Pave seatpost with the zertz inserts - what do people think of this versus the more conventional S-Works SL Carbon 2 bolt seatpost ? The seatpost has to be a layback post.
Thanks

 

Thanks CampyBob, weird you should post that pic, as I've chosen exactly the same seatpost!

 

Is carbon that terrible for seatposts and handlbars afterall?

I remember reading the CPSC website of some carbon seatposts being recalled by Giant bikes I think.

By the way, I was watching this BBC4 show yesterday, "The ride of my life, the story of the bicycle", with a guy buying top-end parts to build a frankenbike and he was opted for a "graphite handlebar". Does anyone know what this is???

 

That's only one example. Others can be found, but it's still a small sample size. I had a Campy carbon post come unglued on me. Any post can fail. Poking a hole thru the side of a seatpost...weird. Rider weight. riding style, rough roads, etc. should all be considered in choosing a structural component.

You might ride forever on the zertz model. Specialized re-designed the Pave model since that picture was taken. Re-designed due to failure rate? Who knows?

I like the Specialized 2-bolt carbon models, myself.

 

No. There has been no horrible rash of CF seat post failures, and there are many CF seat posts out there being used. It'd be big cycling news if they were failing at some alarming rate. The last seat post failure I saw involved an alloy post. The more important question is when a part fails, why did it fail?

 

"By the way, I was watching this BBC4 show yesterday, "The ride of my life, the story of the bicycle", with a guy buying top-end parts to build a frankenbike and he was opted for a "graphite handlebar". Does anyone know what this is???"

No clue.

Graphite was a model of aluminum handlebars that was maunfactured by Icon. Graphite is a term often used interchangeably with carbon fiber...as in graphite fishing rods, etc.

One of the early carbon fiber (carbon-aluminum lay-up) frames was called Graftek...for graphite. Article on graphite v. carbon fiber and the explanation of carbon fiber with graphitic structure:

"The atomic structure of carbon fiber is similar to that of graphite, consisting of sheets of carbon atoms (graphene sheets) arranged in a regular hexagonal pattern. The difference lies in the way these sheets interlock. Graphite is a crystalline material in which the sheets are stacked parallel to one another in regular fashion. The chemical bonds between the sheets are relatively weak Van der Waals forces, giving graphite its soft and brittle characteristics. Depending upon the precursor to make the fiber, carbon fiber may be turbostratic or graphitic, or have a hybrid structure with both graphitic and turbostratic parts present. In turbostratic carbon fiber the sheets of carbon atoms are haphazardly folded, or crumpled, together. Carbon fibers derived from Polyacrylonitrile (PAN) are turbostratic, whereas carbon fibers derived from mesophase pitch are graphitic after heat treatment at temperatures exceeding 2200 C. Turbostratic carbon fibers tend to have high tensile strength, whereas heat-treated mesophase-pitch-derived carbon fibers have high Young's modulus and high thermal conductivity.

A carbon fiber is a long, thin strand of material about 0.0002-0.0004 in (0.005-0.010 mm) in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber. The crystal alignment makes the fiber incredibly strong for its size. Several thousand carbon fibers are twisted together to form a yarn, which may be used by itself or woven into a fabric. The yarn or fabric is combined with epoxy and wound or molded into shape to form various composite materials. Carbon fiber-reinforced composite materials are used to make aircraft and spacecraft parts, racing car bodies, golf club shafts, bicycle frames, fishing rods, automobile springs, sailboat masts, and many other components where light weight and high strength are needed."

 

Hmmm thats interesting... I was looking at some CF stuff at some point but from bike companies websites. Havent read much about the material though.
By the way if someone wants to have a look at this show, its not too bad I think: /img/vbsmilies/smilies/smile.gif



Its made in factories like Cinelli (where the graphite handlebar was recommended), Campagnolo, Continental etc.

 

After I cracked the carbon post that came on my Giant TCR, I replaced it with a Ritchey Pro Carbon post, http://www.excelsports.com/main.asp?page=8&description=Pro+Carbon+Seatpost&vendorCode=RITCHEY&major=1&minor=19. Not terribly sexy, but rugged as any carbon post out there, and comfortable, too. I believe all Ritchey stems, bars, and posts are excellent, but this is the post I can recommend from experience.