I'm thinking about swapping out my Ultegra crank and bottom bracket for something lighter and stiffer and the 7800 crank came to mind. However, I'm wondering if this is a viable solution or just wasted money. Shimano's site says:
Will the new cranks (FC-7800) work with my current 9-speed set up?
The new cranks are designed to be used with the new front derailleur (FD-7800) and chain (CN-7800). The pickup pins and ramps of the new crank will work best with these new parts.

Are the current 9-speed front derailleurs compatible with the new Dura-Ace crankset (FC-7800)?
No. Only the new Dura-Ace front derailleur is designed to work with the new Dura-Ace crankset.

However, reading cyclingnews' article (link) on Chris Horner's bike it mentions he's still using 9 speed dura ace, but with the 7800 cranks. Any ideas on this possible setup?

Dont know about ShimaNo, but Campagnolo makes basically the same claims about their equipment. They say the 9 speed front changer does not work with the 10 speed cranks and that the 9 speed crank does not work with the 10 speed chain. All B.S. in order to sell new equipment. I cant imagine that ShimaNo is any different in this regard.

Doesn't R&D stand for Ripoff and Duplication in the Bike market?

i recently installed the new 2004 dura ace crankset on my klein quantum road bike.All other components are 9 sp and everything works pefectly.I have never hade any problems up to now after about 1000kms and everything works smoothly.

hi there,may i know what chain are u using? 9 or 10 speed? Does using 9 speed chain on the 7800 crankset works? How abt the FD ?? pls elaborate more,thanks

_________________
italian bikes rules!

I've used a 9sp cassette on DA10 setup to complete a race (generous friend) and the chain sat well on the 9sp cassette. I would imagine the rings would be less trouble.

I hope that helps.

Brian

i am using 9 sp dura ace chain with ultegra 9sp casette.my front derailleur is 105 for double shainring crankset.my shifters are ultegra 9sp.rear derailleur also ultegra 9sp.conclusion is that the 9sp chain sits perfectly on the 10sp dura ace cranks.

my plan is same as BigFloppyLlama mention.planing to use this crankset with my current ultegra parts. What are the other stuff that we have to bear in mind?? Does the new DA 10 sp bottom bracket have italian thread? currently now using a Colnago Dream frame.thanks again

_________________
italian bikes rules!