Google:
A Di2 (Shimano’s electronic shifting) system on a tandem is highly praised for its reliable and consistent shifting, especially in racing and long-distance scenarios. However, the higher cost and battery dependency are key drawbacks. Some challenges include a limited selection of compatible triple chainring setups for road tandems and the complexity of maintenance and disassembly for travel.
Advantages
Shifting Performance:
Di2 offers very fast, consistent, and precise shifting that is reliable every time, a significant advantage on a tandem where consistent performance is critical.
Mechanical Advantage:
Di2 is generally considered more reliable and requires less maintenance than mechanical systems once installed.
Adjustability:
Shimano’s Di2 systems offer extensive adjustability for the shifters, allowing for a comfortable and customized setup for both the captain and stoker.
Customization:
Modern Di2 systems offer features like multishift and on-the-fly trimming, which allow riders to fine-tune the system as needed.
Disadvantages
Cost:
Di2 systems are a significant financial investment compared to mechanical systems.
Battery Dependency:
Di2 requires a rechargeable battery, making it dependent on power for shifting.
Maintenance and Complexity:
Di2 systems can be more complex to maintain and troubleshoot than mechanical systems.
Travel Issues:
For coupled tandems, disconnecting and reconnecting the wires for travel can be inconvenient, making wireless systems like SRAM AXS potentially easier for some users.
Gearing Limitations:
For traditional road tandems, getting a suitable triple chainring setup with electronic shifting can be challenging as the industry is moving away from triples.
Summary
Tandem Di2 reviews are generally positive, highlighting the system’s superior shifting performance and reliability. It is an excellent choice for serious riders who want a high-performance, low-maintenance shifting system. However, the high cost and the complexities of battery dependency and maintenance are significant drawbacks that potential buyers should consider. For those who travel frequently, the complexity of the wired system may make a wireless electronic system a more practical option.
Here are a couple of links that I found useful:
similar conversion – but on a DaVinci (lots of photos)
parts kits for tandem Di2/3 conversions