Originally Posted by
Jeff Wills
*Snork*!! He said "trivial software problem"... hee- hee!!
Well, maybe- in the sense that the tools are out there and there are apparently people with the skills to use them to who could make this happen. (See the Fairwheel Bikes link above.) That doesn't mean that reverse-engineering the software/middleware/firmware of the Di2 system is easy and/or straightforward. It takes people with talent and persistence to rewrite this stuff.
I didn't say it would be easy, especially as Shimano isn't know for their straightforward and open policies. However, software issues are much easier for a hobbyist with far too much time on their hands to work through than hardware. However, as the Fairwheel bike shows it can be done, and that there are people with talent and persistence working on it.
Or else, someone can just hack it together using an arduino, for street cred.