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01-12-21 | 07:03 PM

#1

sdodd

Junior Member

Joined: Sep 2020

Posts: 86

Likes: 43

Tandem DI2 conversion - DaVinci 3 x 11

Hi All,

I know that others have shared Shimano Di2 conversions on singles and Tandems in the past. Those posts were extremely helpful in my conversion. I just wanted to share / document what I did so that others interested could see. I have a bunch of pictures so I expect to make 4-5 posts in a row to get them all up.

We have a 1997 DaVinci Tandem that had a 4x8 shift system when we got it. The front shifts were relatively smooth due to the small 6 tooth steps, but no matter how much I played with the system I was always struggling to keep gears from clanking and make sure every shift was smooth. I played with a 4x10 setup for a while but it only exacerbated the issues as the spacings were tighter. I looked at SRAM etap/AXS systems and Di2 systems for improved precision. I REALLY liked the wireless of the AXS. But, there is only a 2x option and I wasn't quite ready to give up the gear range and short steps with the DaVinci unique front gearing. But, Shimano still makes/sells a 3x front Derailleur for Di2. So, that was my path.

The summary is that I am extremely pleased with the conversion! Shifts are crisp, adjustment can be done real-time, synchronized shifting maximizes my gears, and we can shift under power in most situations. The 3x front derailleur works well for us. And, with the display, I can see what gear I'm in without looking back through two sets of legs!
The biggest drawback is that I also had to move my primary road bike to DI2. Having one bike on Shimano shifting and the other on Campy provided too many mis-shifts for my stoker to be happy.

For reference, my go-to site for DI2 info was 'bettershifting.com'. Great info/tutorials and everything has been kept current through the generations of DI2. https://bettershifting.com/building-...hs-and-wiring/

The components I purchased were:
Shifters - ST-R8050 (Ultegra DI2) - $250
Front Der - FD-M9050 (XTR DI2 triple) - $200
Rear Der - RD-M9050-SGS (XTR DI2 long cage) - $300
Cassette - CS-HG800-11 (Ultegra 11-34 11 speed) - $80
Chain - CG-H701-11 (Ultegra 11 speed) - $30
Battery - BT-DN110A (Internal Battery) - $120
Battery Holder - SM-BTC1 (External battery mount for Internal battery) - $50
Wires - EW-SD50 (DI2 wires - 1600, 650, 400, 400, 350) - $25 each
Wire Covers - SM-EWC2 (300mm and 50mm wire covers in black) - $13
Gear Indicator / Bluetooth / power connector - SC-MT800 (XT display) - $80
Front Derailleur Eccentric - Jtek Eccentric Front Mech shim 28.6-34.9 - $20 (cheap part, shipped from UK)
Front Derailleur Hanger - SM-FD905-H - $25
3 Gear front cluster from Todd at Davinci Designs - $90

Prices are approximately what I paid - though I looked long and hard for the best prices I could find around the world. Used equipment should work too. As it was my first DI2 build I didn't want to have something weird happening with used equipment.

Here is my bike before I started and the following picture of the finished product