# # Teeth Cassette Capacity



## mmpotash (Apr 2, 2008)

I have 10 year old 9-speed Ultegra 6500 components on my bike with a standard double crank and a 12-27 cassette. Except for chainrings, chains and cassette I haven't replaced any of the components. I now live in Colorado and am riding Ride The Rockies in June. I want a lower gear and have 2 questions:

1. Is it possible to put a rear cog with more teeth then the 27t? Currently I'm using a RD-6500 SS derailleur but have a spare RD-6500 GS, so I believe that will not be an issue. Does Shimano make a 12-29t cassette or is a mountain bike cassette possible?

2. I thought about converting to a compact crankset but since I believe I have an Octalink BB and a 9-speed system I didn't know if that was workable. Has anyone done this successfully without creating shifting problems? How?


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## mmpotash (Apr 2, 2008)

I see that the SRAM PG-970 Mountain 9-Speed Cassette comes in 11-32 and 11-34 sizes. Would the Road RD-6500 SS or GS derailleur work or would I need a mountain bike derailleur? Would my Ultegra 6500 road shifters work with a Shimano mountain bike derailleur?


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## Al1943 (Jun 23, 2003)

The 6500 SS and the 6500 GS have the same large cog limit of 27 teeth but that limit can usually be extended up to 30 or possibly in some cased up to 32 teeth. The 6500 GS has a long cage and a greater chain wrap capacity. A Shimano mountain bike 9-speed rear derailleur will work perfectly with the 6500 shifter and will definitely work with a big cog up to 34 teeth. A Shimano 10-speed rear derailleur is not compatible with your 9-speed shifters due to a change in actuation ratio. A 9-speed Shimano rear derailleur and 12-32 or 12-34 9-speed cassette would work well for you. The ratio jumps and cadence jumps with each shift will be pretty big but for a serious mountain ride it may be the best choice. A 9-speed SRAM cassette will also work with the Shimano 9-s mountain RD.
With a mountain cassette you will also need a longer chain.


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## mmpotash (Apr 2, 2008)

Thanks! After more research that is what I thought but wasn't sure.


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## ericm979 (Jun 26, 2005)

A Shimano 9sp MTB derailleur will work with your shifters. The road triple may not be able to shift to the 32 or 34t cog.


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## aclinjury (Sep 12, 2011)

I believe FSA makes compact crank for the Octalink BB. I remember seeing them on Ebay. But 9-spd mtb cassette and derailleur will work too.

for example,
RITCHEY WCS Compact Crankset 175mm 50 34 Octalink 110 BCD Road or Cyclocross | eBay


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## mmpotash (Apr 2, 2008)

I ordered a Shimano XT derailleur/cassette (11-32) and a new chain. That way I get a higher gear, get a lower gear, but lose some increments between gears.
Thanks for the advice!


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