Originally Posted by
Iride01
Assuming the rear DR can handle the front 16 tooth difference in chain ring size the 46/30 is along with the total capacity, then the Di2 should have no problem. You might not have the correct ratios and stuff represented in eTube or on your GPS devices, but it will shift when told to shift.
AFAIK, full synchro doesn't need to know the gear sizes. All you tell it to do is how many cogs to auto shift the rear up or down when when you shift the front or when to shift the front when a certain cog is reached on the back. Though please read what I mean and maybe not so much what I wrote. I don't think I explained it very well. <grin>
Been a while, but I think this is correct. I recall while using the e-tube software, the ability to define to what cog the system will shift. Thats how you set the Synchro move, but you need to look at a gear chart to determine to which cog to move to,