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9 Speed cassette adapted to 7 speed hub body?

Old 08-01-17, 01:29 PM
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FrenchFit 
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9 Speed cassette adapted to 7 speed hub body?

All Shimano HG, MTB wheel hubs. Shifter is Shimano 9 speed , MTB.

Is it as simple as dropping one or two largest sprockets on a 9 speed, put the remainder on a 7 speed hub body, adjust the limit on the derailleur?

I have a nice old 7 speed MTB rear wheel, might keep it if I can simply modify a used 11-34 9 speed cassette for a back-up rear wheel, 11-28 would be fine for cruising.
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Old 08-01-17, 01:36 PM
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It is common to mount "8 of 9". That was done on old 7 speed Sachs dual drive hubs.

Usually both 11T and 12T Shimano sprockets can be used as a first sprocket, although they may require different lock rings. Ultegra and Dura Ace cassettes often have common carriers for big sprockets. Otherwise, many cassettes are riveted together which would need to be separated.

Oh, also some 7 speed freehubs will not take an 11T sprocket.


The freehub on the left has a groove along the top to take a 11T sprocket. The freehub on the right doesn't have this groove, and is technically not compatible with a 11T sprocket.

If the hubs are Shimano, you may also be able to mount an 8/9/10 speed freehub, but that may mean tinkering with spacers and dishing.

Last edited by CliffordK; 08-01-17 at 01:43 PM.
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Old 08-01-17, 01:40 PM
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It's commonly called "8 of 9 on 7" if you want to search. Essentially 8 of the 9 speed cogs will fit properly on a 7 speed freehub and will shift with a 9 speed shifter. Usually a smaller cog is sacrificed since the larger ones are often connected. Easy to replace an 11t cog and lock ring with a 12t cog and ring, for example.
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Old 08-01-17, 02:04 PM
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Thanks, very useful information.
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Old 08-12-22, 05:58 PM
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In an interest of keeping similar information together I'm resurrecting this thread.

I'm planning on purchasing a 13-25 9 speed cassette and running it as an 8 speed 14-25 on my 7 speed hub.

I've seen differing opinions regarding needing a new "1st position" ring with the grooves to help the lockring hold the cassette, as opposed to just using the flat 2nd position cog as the 1st. I would like to do this on a budget, but I would also like to be safe. Thoughts?
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Old 08-12-22, 11:10 PM
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Originally Posted by Piff View Post
In an interest of keeping similar information together I'm resurrecting this thread.

I'm planning on purchasing a 13-25 9 speed cassette and running it as an 8 speed 14-25 on my 7 speed hub.

I've seen differing opinions regarding needing a new "1st position" ring with the grooves to help the lockring hold the cassette, as opposed to just using the flat 2nd position cog as the 1st. I would like to do this on a budget, but I would also like to be safe. Thoughts?
Get a 14-25 9 speed cassette.
The end cog is specific for that position since it has a built in spacer.

14-15-16-17-18-19-21-23-25
You probably want to drop the 18T.

Last edited by Bill Kapaun; 08-12-22 at 11:15 PM.
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Old 08-12-22, 11:38 PM
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Originally Posted by Bill Kapaun View Post
Get a 14-25 9 speed cassette.
The end cog is specific for that position since it has a built in spacer.

14-15-16-17-18-19-21-23-25
You probably want to drop the 18T.
Aha, that's a simpler method. Thank you.
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