Cannondale Tandem Conversion to DI2 11 Speed
I just finished my winter project; converting our 2015 Cannondale Road Tandem 2 to DI2 11 speed! I received a lot of help from this form, so I wanted to share the result. Here are a few key points to this project:
• I built the configuration around the 11-40 XT Shimano cassette since it is one the few 11 speed cassettes that work with a 10 speed wheel. This bike has DT Swiss 540 hubs and can't use a normal 11 speed road cassette.
• I used a Wolf Tooth Road Link to extend the Ultegra 6870 GS rear derailleur to 40 tooth capacity.
• I moved the 52 tooth chainring to the middle position and found a 38 tooth 74 BCD chainring on eBay to replace the granny gear. I then added a chainring guard to the outer position to make it look cool!
• I added the D-Fly DI2 wireless module, so I see the current gear selection on my Garmin display. The Garmin also shows the DI2 battery charge level and pops up a warning when the charge goes below 20%.
We are waiting for nicer weather before we take our first ride, but shifting performance on the stand is quick, clean and precise. There is no hesitation on any shifts either up or down. My configuration exceeds the chain wrap capacity so I can’t use the 52 – 40 gear, but that is not a practical gear to use anyhow, so I’m not too concerned. Thanks for everyone’s help!