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Old 04-03-06, 11:30 AM   #1
jacewb
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9 speed on a 7 speed ????

I just got a MINT Trek 6000zx bike (easton frame) for free. I was moving the grip shift and broke the shifter.
I just bought a BRAND NEW Deore shift/brake combo on Ebay ($14). These are a 9 speed shifting system, can this be used on a 7 speed system.
I thought if a adjust the limit screws so the shifter would not try and through the chain, it would be ok.

Thank you for your time and effort
Jace
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Old 04-03-06, 12:20 PM   #2
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No. You must match the number of speeds of the shifter to the number of cogs in the cassette. Your derailleur will work with 9-speed stuff though, if you decide to upgrade.
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Old 04-03-06, 12:25 PM   #3
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No,it won't work.A 9 speed shifter will move smaller distances than a 7 speed shifter,so it won't line up with a 7 speed cassette or freewheel.Your best bet would be to get a cheapo 9 speed wheel-cassette combo off ebay.Make sure your rear spacing can accomodate it-135 mm.You probably can't stuff a 135 hub in a 126mm spacing,but the rear wheels usually have a spacer you can remove(it might make the rear wheel slightly out of line with the front wheel,but it isn't a high speed motorcycle,so no big deal).Luck,Charlie

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Old 04-03-06, 12:44 PM   #4
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Actually you might be able to do this -- sort of. Sheldon Brown has a bit on using 8 out of 9 sprockets of a 9-speed cassette with 9 speed shifters, on a 7-speed freehub here. You would need to pick up a 9-speed cassette if you don't already have one.
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Old 04-03-06, 01:14 PM   #5
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so it plain won't work?

will it not pull enough cable?

whats going to happen if i do?
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Old 04-03-06, 01:22 PM   #6
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Originally Posted by jacewb
so it plain won't work?

will it not pull enough cable?

whats going to happen if i do?
It won't index over that 7-speed cassette at all (well, you'll be able to hit the smallest cog and possibly the largest one, but nothing in-between).
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Old 04-03-06, 04:33 PM   #7
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No, it just won't work.The 9 speed shifter will pull just a bit too little cable when it makes its 1st shift.This shift-say from biggest to next biggest,will probably work,but it will be making "noise" the whole time.The next shift will probably not really work-it will be constantly shifting back and forth.You won't be able to get the shifter to line up with the cogs-except for one cog on whichever end you chose.
The 9 speed shifter's cable pulls will just be too short.Luck,Charlie
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Old 04-03-06, 06:38 PM   #8
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'nother gave you the only correct answer. Follow the link he gave you. You take one cog off of a 9 speed cassette. Your new nine speed shifter will work, but you'll only have eight speeds. You'll also need a 9 speed chain.
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Old 04-03-06, 10:02 PM   #9
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Originally Posted by Dirtdrop
'nother gave you the only correct answer. Follow the link he gave you. You take one cog off of a 9 speed cassette. Your new nine speed shifter will work, but you'll only have eight speeds. You'll also need a 9 speed chain.
no, i'm pretty sure the other answers were correct, as a 9 speed shifter will absolutely never work with a 7 speed cassette...

...or you could just spend about $20 and get a new 7 speed MRX rear gripshifter, use your old chain, cassette, and wheel and call it a day.
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Old 04-03-06, 11:13 PM   #10
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no, i'm pretty sure the other answers were correct, as a 9 speed shifter will absolutely never work with a 7 speed cassette...
I think you have misunderstood. The idea is to take a 9-speed cassette, take one of the cogs off, thus making it the width of a 7-speed cassette, and use the 9-speed shifters to shift the remaining 8-cogs. That's why Sheldon calls it "8 of 9 on 7", see.

The other answers were not incorrect per se; they were just not looking at all of the options.
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Old 04-04-06, 01:17 AM   #11
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However it would be weird having sprockets 1 - 7, and not having 8 - 9. You could climb great but you would be pedaling more in the high gear for sure.
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Old 04-04-06, 06:52 AM   #12
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However it would be weird having sprockets 1 - 7, and not having 8 - 9. You could climb great but you would be pedaling more in the high gear for sure.
You won't. You will have either cogs 2-9 or 1-8. More likely 1-8 since you really need the specific top gear cog which has the built in spacer and serrations to mate with the lock ring.

BTW, you will have to get one of the "lower line" Shimano 9-speed cassettes, 105 or below, since you have to remove the largest sprocket. The Ultegra and Dura Ace cassettes have several of the largest cogs mounted on a spider and they can't be removed individually.
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Old 04-04-06, 08:46 AM   #13
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BTW, you will have to get one of the "lower line" Shimano 9-speed cassettes, 105 or below, since you have to remove the largest sprocket. The Ultegra and Dura Ace cassettes have several of the largest cogs mounted on a spider and they can't be removed individually.
This is true. You could also get a Shimano-compatible 9s cassette with individual rings from SRAM or Performance -- usually a lot more affordable than Shimano-branded.

Edit: you could also get a "mountain" 9s cassette. It doesn't need to be from a "road" group; the spacing is the same.
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Old 04-04-06, 09:12 AM   #14
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Quote:
Originally Posted by jacewb
I just got a MINT Trek 6000zx bike (easton frame) for free. I was moving the grip shift and broke the shifter.
I just bought a BRAND NEW Deore shift/brake combo on Ebay ($14). These are a 9 speed shifting system, can this be used on a 7 speed system.
I thought if a adjust the limit screws so the shifter would not try and through the chain, it would be ok.
Adjusting the limit screws will prevent overshifting, but the indexing won't be correct from sprocket to sprocket...

...however, if you use the "alternate cable routing" at the rear derailer, there's a fair chance you can get it to work OK. What have you got to lose?

See: http://sheldonbrown.com/derailer-adj...html#alternate

I would worry more about the brakes. Your Deore brifters are made for "V brakes" or similar "direct-pull" cantilevers. If your bike has the traditional center-pull style cantilevers, (as most 7-speed mtbs do) the brakes will be very feeble with the new style levers. Fortunately, suitable direct-pull cantis are also cheap.

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Old 04-05-06, 08:05 AM   #15
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Quote:
Originally Posted by jacewb
I just got a MINT Trek 6000zx bike (easton frame) for free. I was moving the grip shift and broke the shifter.
I just bought a BRAND NEW Deore shift/brake combo on Ebay ($14). These are a 9 speed shifting system, can this be used on a 7 speed system.
I thought if a adjust the limit screws so the shifter would not try and through the chain, it would be ok.

Thank you for your time and effort
Jace

Jtek Engineering makes an adapter to make mismatched shifters and cassettes work. He can modify it to suit just about any combo. He modified his stock product to allow my nine-speed shifters to index perfectly with my 8-speed cassette. Call him he may be able to help.
http://jtekengineering.com/
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