I have an 6600 Ultegra 10sp triple bike that had a 12-27 in the back. I wanted the lowest gears I could get in the back.
My SO put a 10sp SRAM 12-36 on the back with a 9sp XT Shadow rear der. Works perfectly.
He set up a friends 105 10sp bike like this also. He used SLX level on hers.
The trick is to use the 9sp rear der., a 10sp one won't work.
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