Adding Extra Gear to Cassette

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05-06-12 | 03:50 AM

#26

Jacque Lucque

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As I said before, I've covered all other bases in terms of 9 speed compatibility. Specifically I'm going to be running DA 7700 Bar End shifters with Deore XT derailleurs.

My question about the cassette was to simply see if I could bodge compatibility out of the rather lovely, newish 8 speed cassette. I am now however just going to banish the cassette to the parts drawer for use in later years!

05-06-12 | 06:08 PM

#27

Al1943

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Quote:

Originally Posted by DannoXYZ

Then the issue of RD comes in. If the one on the Alan is an 8-spd Dura-Ace, it will not work with 9-spd Dura-Ace shifters. Shimano got rid of the unique Dura-Ace cable-pull distances when they went to 9-spd and made Dura-Ace the same as the rest of the line. You may need to get 9-spd compatible RD.

This brings up an interesting possibility. Shimano 8-speed Dura-Ace shifters have the same cable pull as all Shimano 9-speed shifters.
Because of this it is possible to use any Shimano 9-speed rear shifter with an 8-speed Dura-Ace rear derailleur to shift any 8-speed Shimano cassette. https://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946

05-06-12 | 06:21 PM

#28

DiabloScott

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Quote:

Originally Posted by Al1943

I don't think so. Shimano 8, 9, and 10 are all compatible shifter/derailleur mech EXCEPT for DA8. So you could use any Shimano 9-speed shifter with any 8-speed cassette exDA.

05-06-12 | 06:51 PM

#29

Al1943

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Quote:

Originally Posted by DiabloScott

I don't think so. Shimano 8, 9, and 10 are all compatible shifter/derailleur mech EXCEPT for DA8. So you could use any Shimano 9-speed shifter with any 8-speed cassette exDA.

No, all Shimano 8-speed cassettes have the same cog spacing. Dura-Ace 8-speed shifters and rear derailleurs are no cross-compatible with other groups. It just happens that the D-A shifter cable pull is the same as all Shimano 9-speed shifters (less one click). The 8-speed D-A rear derailleur has a unique actuation ratio. Read the info in the link I offered above. It's all there.

05-06-12 | 07:36 PM

#30

Reynolds

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Quote:

Originally Posted by FastJake

I'm not sure if I'm misunderstanding you but I think you have a slight error.

7S and 8S spacing is just a tiny bit different. 7S Shimano is 5mm and 8S Shimano is 4.8mm. So you can sometimes go back and forth with the 7/8 shifters/cassettes, but it does not always play well. It can be tricky to get it setup just right if you mismatch.

I used many 8sp minus 1 with 7sp shifters and all worked OK.

05-07-12 | 12:42 AM

#31

DannoXYZ

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Quote:

Originally Posted by Al1943

Interesting... If he's got Dura-Ace 8-spd RD, he can make it work OK on 9-spd cassette by using Shimano 10-spd shifters. Almost perfect, but not as precise as Shimano 9-spd derailleur + 9-spd shifters.

Seeing as how he's using the DA shifters with Deore RD, he's got a compatible 9-spd RD+shifter combo. However, there's no way to re-use the 8-spd cassette as 9-spd without a lot of work.

Last edited by DannoXYZ; 05-07-12 at 12:53 AM.