DA 7700/7800/7900 compatibility

[torquer]

I'm not optimistic that my DA7700 shifting problems I posted about recently(http://forums.thepaceline.net/showthread.php?t=92450) are going to be fixed.
Pricing replacement NOS 7700 shifters ($300 +/-) got me thinking that maybe I should jump into the 10-speed millenium, since Nashbar was selling DA 7900 shifters for $400. That would be fine (I need a new chain and cassette anyway, and going 10-speed isn't that much more), but I read that with 7900 shifters my old front der. won't work anymore, and braking won't be as good. (Don't know about rear der. compatibility.)
What about 7800? Any compatibilty issues there?

[rice rocket]

Nope, everything should work (except the cassette, duh).

All the RDs should be interchangeable. 7900 has it's own FD. Braking changed around, and won't be "optimal" because of different pull ratios, but they'll still brake.

[bikser]

7900 is only B compatible with 7800, so I'd think give we're talking 9 speed 7700 to 10 speed it really would not work well together. Front shifting definitely wouldn't work, different pull all together, and braking would not be very smooth. There are plenty of deals on 7900 front derailleurs, but brakes would set you back another $200+. Ultegra 6700 would be a good alternative, or mixing and matching with 7900.

[dave thompson]

Disagree with the brake statements, your existing brakes will work very well. 7900 will work better.

If you want 10-speed with full backwards compatibility with earlier 10-speed stuff; 5600/6600/7800, look at the Ultegra 6700 components. Speaking from personal experience.

[torquer]

Just to be clear, I'm asking about 7800 shifter compatibility to 7700 der.s and brakes.

[rice rocket]

Yes and yes.

[Cat3roadracer]

If you can swing it financially, upgrade the whole kit. I went from 7700 to 7900 and amazed at all of it.

[nachoman]

If you can swing it financially, upgrade the whole kit. I went from 7700 to 7900 and amazed at all of it.
I went from 7800 to 7900 (well really Di2) and was very happy too with the upgrade. Obviously the shifting on the Di2 is superior, but I was a bit amazed at how much better the braking was.

[false_Aest]

I just upgraded to 10-speed DT shifters.


Brilliant idea.

[oldpotatoe]

I went from 7800 to 7900 (well really Di2) and was very happy too with the upgrade. Obviously the shifting on the Di2 is superior, but I was a bit amazed at how much better the braking was.

I would say the FD shifting, with the 7900 crank(big ring), Di2 is amazing but the RD..you either push a button or push a lever, the RD moves, selects a gear. Di2 is not faster(actually slower if you need to select more than one lower gear), very consistent over time but I wouldn't characterize the RD shifting as 'superior', IMHO.

[Bob Loblaw]

If you're looking at 7800, all you need are brifters, chain and cassette.

On one of my bikes I am running a 7700 RD, 7800 FD, 6600 brifters, SRAM cassette and 7 speed cranks.

The only thing I'd change is the SRAM cassette to speed up the rear shifting. Other than that it works great.

BL