Dura-Ace 7900 or Ultegra 6800 crankset?

[jojoma]

Hi,

I have been riding the 7900 compact crank for a few years and it has been fantastic. Stiff as concrete, and light as a feather. But, I am moving to the new Ultegra Di2 group soon, and I'm wondering if I should make it a complete overhaul and swap the 7900 crank for the 6800. Of course, I would only want to use the 6800 crank if it's better (or as good) as the 7900. Any thoughts? I don't like the 4-arm look of the new Shimano cranks, but if they are stiffer and better, I'll ride it. Thanks a lot

 

[steve]

Originally Posted by jojoma
Hi,

I have been riding the 7900 compact crank for a few years and it has been fantastic. Stiff as concrete, and light as a feather. But, I am moving to the new Ultegra Di2 group soon, and I'm wondering if I should make it a complete overhaul and swap the 7900 crank for the 6800. Of course, I would only want to use the 6800 crank if it's better (or as good) as the 7900. Any thoughts? I don't like the 4-arm look of the new Shimano cranks, but if they are stiffer and better, I'll ride it. Thanks a lot

Hi there

I'm not sure how current this is, but the dura ace crankset is 101 grams lighter.

Shimano
Dura Ace Di2 Shimano
Dura Ace 7900 Shimano
Ultegra 6700 Shimano
105 5700 Crankset 636 636 737 834 BB Cups 89 89 102 102 Shift Lever 459 448 490 492 Rear Derailleur 225 166 209 232 Front Derailleur 124 67 89 112 Chain 249 249 280 291 Cassette 163 163 204 205 Brake Calipers 293 293 330 356 Battery + Loom 137c n/a n/a n/a Group Weight in g 2375 2111 2441 2624 Group Weight in lb 5.23 4.65 5.38 5.78
above is from total cycling.

Edit: above table has weights for 6700 not 6800.

 

[oldbobcat]

Quote:

Originally Posted by jojoma .
Hi,
But, I am moving to the new Ultegra Di2 group soon,
Di2 6800 or 6700?

 

[jojoma]

I'll be installing 6870 Di2 soon. (The new Ultegra Di2.) Everything on my frame is going to be Ultegra 6870, expect perhaps for the crankset. That is what I am unsure of. My options are:

1. Keep the 7900 crank
2. Swap the 7900 for the 4-arm Ultegra 6800 crank (it would be about a wash from a cost perspective)
3. Upgrade to the 9000 crank (and continue to pay a small fortune for Dura ace chainrings)

 

[oldbobcat]

The interface between Shimano chains is tightly linked (get it?), with 7900 and 6700 cranks optimized to work best with asymmetric (directional) 10-speed Shimano chains. I'd bet, but don't have definitive data supporting, that your 11-speed setup would shift better with 6800 cranks and rings.

The question should be, Is anybody out there using 7900 cranks with a 6800 or 9000 11-speed drivetrain, and how does it shift?

 

[mike 6843]

I'm about to purchase the Ultegra 6870 Di2 as well and I'm wondering if I can continue to use my Dura Ace 7900 crank or do I have to buy a new Ultegra Crank?