The new Ultegra RX derailleur comes in mechanical RD-RX800-GS and Di2 RD-RX805-GS models. Both use the company’s Shadow technology and have the same low-profile appearance as the R8000 and R8050 ...

In this case, Shimano went off book with their DI2 groupset, leaving [kwakeham] with a reverse engineering job on his hands. [kwakeham] gives us a great example of how to approach reverse engineering.

The Selle Italia SLR Boost Superflow saddle is a treat when you’re on it too, while the shifting comes from Shimano’s Ultegra Di2 groupset, and that as it turns out is one of the highlights here.