I'd like to convert my mechanical 6800-based S3 2014 to 6870 Di2.
The internal battery option is very appealing, and has been covered multiple times, but there is one important unanswered question: does it apply to frames of all sizes?
If you look at my 48 cm S3, the seat tube is pretty short:
Do you know if it fits? Does the internal battery fit into the lowest (narrowest) part of the seat tube? If it only fits on the top part, I fear it might be a no-go.