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-   -   HELP! Shimano Dura Ace shifter question (https://www.bikeforums.net/classic-vintage/1184857-help-shimano-dura-ace-shifter-question.html)

jdawginsc 10-01-19 06:13 PM

HELP! Shimano Dura Ace shifter question
 
Firstly, I am a Dura Ace newbie.. Okay, so I have Shimano 7700 RD/FD and 7900 shift levers for the down tube (they look intimidating to install). Dummy me bought the pair of shifters with flat boss washers instead of radius-ed ones.

<I also have a pair of bar ends that came with my Brewsmith Dura Ace package, but not sure whether I want to go bar-ends.>

My question is that there are ebay radius-ed boss washers that state Shimano 7800, and SL-6208...Will these work with them? Is the 7900 proprietary? Also will the 7900s work well enough with the 7700 derailleurs?

https://www.ebay.com/itm/Shimano-780...cAAOSwkLhaPesq
https://www.ebay.com/itm/Shimano-SL-...sAAOSw47NdUd~0

No matter what, I seem to be going in a direction where I will have extra parts due to my indecision... :(

Classtime 10-01-19 06:18 PM

Your shifters will work fine with your derailleurs. I currently use the 7900 DT shifters with 7700 derailleurs on my go fast bike. Two years ago, with same bike and derailleurs, I use the 7900 bar ends which also worked fine. I'm pretty sure that the bosses will work as I have no idea where I got mine.

rccardr 10-02-19 12:34 AM

The bosses will work fine, they haven't changed much in 30 years.

jdawginsc 10-02-19 03:45 AM

Thanks guys!

RobbieTunes 10-02-19 05:02 AM

Just remember that the 7900 L shifter is mounted at 270 from "rest." You push the shifter onto the boss until it "sets," then rotate it counterclockwise about 270 degrees to where it stops. It will not be in line with the downtube.

RiddleOfSteel 10-02-19 03:01 PM

^^^ What he said. The shifter boss washers will have that inner raised rectangular portion facing forward--in line with the downtube. The right shift lever will mount in line with the downtube. The left shift lever is spring-loaded and will mount pointing downward, 90 from the the direction of the downtube. Once you spin the bolt on (with that D-ring for your fingers to work) and snug it, then you rotate/spin the shift lever counterclockwise almost 270 where you will feel it stop. It will not stop parallel to the downtube, but will be about 20-25 "short" of it. This is to facilitate the right hand working both levers at the same time if needed (or so the logic goes).

Of course if you received instructions with the package, they should suffice.

7900 was the last Dura-Ace era to work with the standard 1.7:1 rear derailleur cable pull ratio, which began in the mid/late '80s when they introduced their SIS/indexed shifting (minus 7400-era Dura-Ace, which played on its own team). 7700 and 7800 play ball, as do many other Shimano groupsets.

ljsense 10-02-19 03:09 PM

I've run this set up many times. I used to think that the shift boss covers corresponded to indexing, but they're all the same. Everyone gave good advice above.

jdawginsc 10-02-19 03:45 PM

Awesome guys! Thank you for the instructs...!


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