# Dura-Ace FC-7800 and 7900 Crankset Compatibility



## beetz12 (Aug 14, 2008)

I am getting the Dura-Ace 7800 double crankset. 

Does anyone know if it's compatible with the Dura ace 7900 BB.


----------



## Dr_John (Oct 11, 2005)

Yes. Here's the compatibility chart:

http://dura-ace.com/start.htm (sorry, since it's buried in Flash, you'll have to click to find it. It's under downloads).

And watch out for those DA cranks on Chainlove. The one's I've seen there have had odd sized chain rings. And if you intend to buy it and change the chain rings, do look at what Dura Ace chain rings cost. You won't be saving any money.


----------



## Dr_John (Oct 11, 2005)

What the heck. He's a screen cap of the 1-page PDF:


----------



## beetz12 (Aug 14, 2008)

Amazing! Thanks for the awesome chart. This one is definitely a keeper!

Sorry this may be a dumb question. I really don't know much about bike repair - so I have to ask: What constitutes an 'odd-sized' chain ring and what's a common size that most people use?

It's funny you mentioned chainlove because that's exactly where I was going to get the DA crankset. Hopefully they have another deal on this soon. 

Thanks for your help!


----------



## Dr_John (Oct 11, 2005)

> It's funny you mentioned chainlove because that's exactly where I was going to get the DA crankset


Wasn't that in your original post before you edited it? 

I believe the inner ring was 42, and the crank length was a bit unusual. Of course you replace the inner ring with a cheaper alternative.


----------



## Dr_John (Oct 11, 2005)

Actually it was a 54/42:

http://forums.roadbikereview.com/showthread.php?t=141785


----------



## beetz12 (Aug 14, 2008)

lol I thought no one saw it.

You are right about the chain ring size from CL. I'm guessing most people usually go with a smaller inner chain ring.


----------



## beetz12 (Aug 14, 2008)

Someone on bikeforums.net referred me to PBK for the dura-ace crank. 

http://www.probikekit.com/display.php?code=D1039

After you add it to your cart, the price falls to 130GBP (or about 230 USD). 

They also provide sizes that are probably more common. 

Good deal?


----------



## iliveonnitro (Feb 19, 2006)

So does this mean I cannot use ST-7900 front/rear shifters with my 7800 derailleurs?


----------



## beetz12 (Aug 14, 2008)

iliveonnitro said:


> So does this mean I cannot use ST-7900 front/rear shifters with my 7800 derailleurs?


It sure does from the looks of it.


----------



## Dr_John (Oct 11, 2005)

> So does this mean I cannot use ST-7900 front/rear shifters with my 7800 derailleurs?


Yes, and I've read that somewhere before. What's more odd to me is that the 7900 brakes are not compatible with 7801 STI's. Shimano's typical very conservative with their compatibility, but that one I just can't understand.


----------



## HammerTime-TheOriginal (Mar 29, 2006)

Dr_John said:


> What's more odd to me is that the 7900 brakes are not compatible with 7801 STI's. Shimano's typical very conservative with their compatibility, but that one I just can't understand.


The answer is here http://www.fairwheelbikes.com/forum/viewtopic.php?t=4624&start=46


Also, the above chart says that 7900 chain is not compatible with 7800, 66xx chainwheels. Does this mean that 7900 chain "can't" be used with non-Shimano cranks such as Campy 10 speed?


----------



## Dr_John (Oct 11, 2005)

> The answer is here http://www.fairwheelbikes.com/forum/...=4624&start=46


 Thanks. :thumbsup:


----------

