# 7800 and 7900 cassette, REAL difference?



## MerlinDS (May 21, 2004)

Any real difference in the two, weight, durability, anything? I did a search couldn't find anything here.


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## bdaghisallo1 (Sep 25, 2007)

Not really. I ran 7900 for a year and have been running DI2 for two and a half years, all with 7800 cassettes. They work just great with the 7900 chains.


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## tihsepa (Nov 27, 2008)

MerlinDS said:


> Any real difference in the two, weight, durability, anything? I did a search couldn't find anything here.


Price maybe?


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## marathon marke (Nov 14, 2011)

bdaghisallo1 said:


> Not really. I ran 7900 for a year and have been running DI2 for two and a half years, all with 7800 cassettes. They work just great with the 7900 chains.


So it's okay to use a 7900 chain with either 7800 or 7900 cassette, but the 7800 chain won't work properly with a 7900 cassette?


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## bdaghisallo1 (Sep 25, 2007)

I haven't run a 7800 chain with a 7900 cassette since I don't have any 7900 cassettes. But I would imagine that, as with most Shimano compatibility dictates, it will work only about 98% as well as a full 7900 combination. I am a big Shimano fan, but most of their compatibility statements, within a given family of product lines (ie 10sp road groups) are more about boosting sales by getting consumers to go whole hog on like numbered components.


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## Cut.Aussie (Mar 19, 2011)

I have 7800 on one set of wheels and 7900 on the other and chop and change wheels depending on expected winds and number of hills, I could not pick the difference between the two cassettes.


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## alanw2007 (Jan 4, 2009)

7900 has one more titanium cog than 7800, so should be marginally lighter.


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