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DI2 7970 Question about Cassette Change

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DI2 7970 Question about Cassette Change

Old 05-14-21, 09:12 AM
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helmet4000
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DI2 7970 Question about Cassette Change

I just got a bike with 10-speed di2 (7970 version) and it has an 11-25t cassette. This is my first time with electronic shifting and I do love it. If I were to install a 11-26t (one extra tooth on the larger cog) do I need to do anything to reset the system or does it automatically detect the change when activated?
(the manual says the max is 27 teeth).

But possibly I might want to just get a 12-27t cassette which is a more distinct change.

Thank you for any help.
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Old 05-14-21, 09:33 AM
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cxwrench
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What would it 'detect'? No, you don't have to reset anything. Confirm limit screws are correctly adjusted. Your older Di2 doesn't behave differently because of different cog sizes. It moves the chain sideways just like any other derailleur.
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Old 05-14-21, 12:27 PM
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By "detect" I meant the one extra cog. Thanks for the information, greatly appreciated.

“cog” should have been “tooth” — I caused much confusion sorry. Hi

Last edited by helmet4000; 05-15-21 at 11:26 AM.
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Old 05-15-21, 08:06 AM
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Have to use 10 speed cassette. No extra gear but you can sub different geared 10 speed cassettes without issue. I have an even larger cassette w 7970 no problem. Can’t remember/find what I have

Last edited by dbf73; 05-15-21 at 08:15 AM.
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Old 05-15-21, 09:10 AM
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Originally Posted by helmet4000 View Post
By "detect" I meant the one extra cog. Thanks for the information, greatly appreciated.
You didn't say you wanted to use an 11 speed cassette. I think you're confused w/ terminology. I don't think you mean cog, you mean tooth. No, that doesn't matter.
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Old 05-15-21, 11:25 AM
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Originally Posted by cxwrench View Post
You didn't say you wanted to use an 11 speed cassette. I think you're confused w/ terminology. I don't think you mean cog, you mean tooth. No, that doesn't matter.
Yup, 10-speed cassette, 11/25t current want to use 11/26t 10-speed cassette.

Thanks for your advice and help.
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Old 05-16-21, 07:15 AM
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ps - found what I have. 11-28 works just fine
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