Hmm: http://flwrider.com/2011/12/09/frankenstein-di2/#more-47046
I ran a 7800 rear on my mountain bike for a while using a 10T upper pulley .. It's worth a try before getting a long cage to convert if you're serious ..
@Oswald started
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I ran a 7800 rear on my mountain bike for a while using a 10T upper pulley .. It's worth a try before getting a long cage to convert if you're serious ..