[XTR]

Limited edition Shimano Dura-Ace FC-7800C hollow Carbon crankset originally retailed at £699.99. This limited FC-7800C chainset was developed specifically for the 7900 series 10-speed current generation groupset. This chainset was briefly fitted to my bike covering approximately 300 miles of use and is in excellent un-worn condition, but is now back in its original box. This carbon chainset looks much the same as the aluminium version, almost as though they just wrapped a layer of carbon over the top, this is not the case. Shimano’s Dura Ace FC-7800C is carefully wrapped leaving hollow arms around aluminium inserts at key interfaces, the spider, the pedal threads, and the left arm’s clamping area. In testing Shimano found this maximised the strength to weight ratio and also helped increase the rigidity they demand while still decreasing weight. The right hand crank is fixed to a steel billet spindle (the steel spindle has been found to be lighter and stiffer than aluminium options). This chainset is compatible with all of Shimano’s proven current road HollowTech II external bottom bracket cups including press fit. Weight for the complete chainset and bottom bracket is a svelte 709g (external BB); the chainset on its own comes in at 609g. Even with this weight loss the end result is a chainset that is a full 10% stiffer than the aluminium version, which was already well known for its exceptional stiffness. This state-of-the-art chainset has anodized black CNC-machined 53/39T chainrings with a crank arm length of 172.5 mm.
£399.99 (plus postage if mailed £12.00, UK only) Please contact Peter on email: petergriffiths020@btinternet.com

Topic

[Thegirlsdad]

Did you manage to sell your
Did you manage to sell your chainset?

I’ve got one as well that I’m contemplating selling as I’ve decided to switch to a compact chainset.

[XTR]

Thank you for your comments
Thank you for your comments on my chainset but let me just clarify some of your remarks.

Firstly the chainrings are not worn but in fact the close up you are looking up clearly shows where Shimano’s patented tooth profile has been developed to specifically aid shifting under load up the chainring.
Secondly as I originally stated this chainset Shimano gave the model name FC-7800C but in fact was only designed for use with the 7900 series drivetrain / groupset. Like you correctly stated this is for use only with the CN-7900 / CN7901 (revised pin structure) directional chains however CN-7900 / 7901 Series directional chains should not be used with the older generation 7800 series groupsets (as your comment would suggest), these should only be used with CN-7800 / CN-7801 (or equivalent era Ultegra / 105 chains). As this is effectively (but not in name) to all intent and purposes a 7900 series chainset it should not be mixed with the 7800 groupset as not only should it use a 7900 series chain but it is developed for the spacing of the FD-7900 front derailleur which in turn requires the ST-7900 shifter.
Finally Regarding the crank arms , again as I stated in my advert this is not as you suggest wrapped alloy arms like a lot of brands on the market but in fact carefully layered up Hollow carbon arms around forged and machined alloy inserts at the spider and pedal tread interfaces. Please follow this link to an image of this in cross section: http://www.bikeradar.com/gallery/article/shimano-launches-carbon-dura-ace-crankset-12255/3

[Gkam84]

Also, just looking through
Also, just looking through some of my info, I think you might need to look again at what it was designed for. You say

“This limited FC-7800C chainset was developed specifically for the 7900 series 10-speed current generation groupset.”

I believe, it was only designed specifically with a 7900 chain in mind, as it will work with all Shimano 10 speed groupsets 7800, 7900 and Di2.

The other part i query is – “This carbon chainset looks much the same as the aluminium version, almost as though they just wrapped a layer of carbon over the top, this is not the case.”

I believe this to be wrong aswell, as the 7800-C was cold forged aluminum wrapped core with visible carbon, Meaning it is pretty much just wrapped in a layer of carbon over the top.

I know all this because i got all the info on it, but couldn’t get my hands on one as only 50 were sold in the UK around Xmas 08 and i was out of the country. :&

[Gkam84]

Woow, If this had been in
Woow, If this had been in “excellent un-worn condition” i would have snapped your arm off to add it to my collection of Limited Edition Shimano stuff, but its clear for all to see the wear on the outer ring’s teeth. :& :”(

As they say in dragon’s den……i’m out.

P.s. why would you fit something that nice with it being limited edition to your bike and only use it a little, it should be all or nothing 😉

[Author]

Replies