Originally Posted by
ReneV
I've converted a 2016 Synapse Carbon: all internal, including the new handlebar junction box, which I would argue is a must. If you can find the Cannondale page for your year, the key term is "Di2 Ready". If you look amongst your spare parts from the original installation, in case you still have them, rubber plugs for the gear-cable holes should indicate "Di2 ready", too.
Was yours a disc or non-disc version?
I also went to the Cannondale page. The current model year Ultegra does list the frame as "Di2 Ready" but when I looked at the Archive Catalogue (2015), it does not mention "Di2 ready" but the catalogue seems quite limited on specs.
If I visit the shop website where I bought my bike, they still have 2015's listed for sale. The specs do show Di2 ready.