FC-7800 crankarm on 9speed drivetrain
 

I know this is kinda weird but the Dura Ace 10spd crankarm is just too sexy for me. I wanted to change my shimano 105 crankarm to this FC-7800 crankarm. Would anyone who use this settings please advice me? Thanks!

Crank ugly. There, I said it. :p

I believe you will have to change both the crank and bottom bracket, as the 7800 crank arms use an entirely different bottom bracket. There is no commonality between your 105 components and the 7800 crank arms

Well said. Gimme the old school look anyday, juice.

I think you get the bottom bracket when you buy a ultegra or dura ace crankarm set - anything with a part number like FC-6600 or FC-7800. the BB is available separately for those who've worn out their bearings, but i've never seen the arms sold apart from the "external" bottom bracket.

My understanding is that the crank will work fine with 9 speed. You will need the matching bottom bracket as the others have mentioned though.

ehh..i thought the FC-7800 crankarm dont use BB anymore though. I just need those 2 pieces of left and right crankarms. FC-7800 is using integrated BB right?

Yes you are correct, the FC 7800 does use an integrated BB. Your original question made it sound like you wanted to know the the 7800 crank arms could be used with your 105 BB.

If you want to replace your 105 crankset then all you need to do is buy the FC-7800 complete crankset/BB.

Oopss..sorry to create some misunderstandings earlier on. I felt a lil bit dizzy these few days. Since it's compatible, i would change this asap! Thanks for your guys help! cya!

You still have to buy the BB cups seperately too.

Sweet looking crank with a muscular look. Ok, cranksets don't have muscle or make you faster....you get my drift.

If you wanted to save some money you could sell off the 10s rings for some good coin. Those rings fetch good prices on Ebay in new condition.

Then just your regular 9s rings with it and buy ultegra or 105 9s replacemnts.

You always use the 10s rings with your 9s set-up as well.

This is correct :)

You need to order a crank set PLUS the bottom bracket bearings which are sold seperately.

I agree, too.