Bicycle Mechanics - 78/7903 Dura Ace 3X Front STI w/2X Chainring Crank

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PDA
55/Rad
08-29-11, 06:21 PM
I've been using Ultegra and 105 triple front STI shifters with double chairing setups for years but somebody claimed this wasn't possible with the newer generations of DA.

Can the triple STI's on the 7800 and 7900 series DA be set up to work with double cranks?

Thanks...

55/Rad

shelbyfv
08-30-11, 03:01 PM
And while we're at it, what about Ultegra 6603? Will they work with doubles as the previous generations did?
55/Rad
08-30-11, 10:36 PM
And while we're at it, what about Ultegra 6603? Will they work with doubles as the previous generations did?

6603 definitely does...I've done that several times.

jimc101
08-30-11, 11:55 PM
As there is no 7903 FR or triple version of the 7900 series Dura Ace available, you can't use this, the direction Shimano and SRAM appear to be going in, is for doubles with big ratio cassettes at the back, there are no DI2 triple versions of Dura Ace or Ultegra
55/Rad
08-31-11, 07:09 AM
As there is no 7903 FR or triple version of the 7900 series Dura Ace available, you can't use this, the direction Shimano and SRAM appear to be going in, is for doubles with big ratio cassettes at the back, there are no DI2 triple versions of Dura Ace or Ultegra

Good information - thanks.

How about the 7800 series?
HillRider
08-31-11, 07:54 AM
I see no reason why a double crank can't be used with a triple brifter. Set the fd's low limit screw to position the fd properly and connect the brifter so you use the outer two or three positions. That way an inadvertant shift to the non-existant granny ring just results in a slack shift cable.

The only problem can be if you set up the brifter so it shifts between the granny and middle positions and then try to shift past the high limit screw. A hard attempt to shift under those conditions can damage the brifter's ratchet.