We recently completed our first official Shimano Ultegra Di2 build with internal cable routing and a hidden battery. Being a bicycle company that custom paints every bike that leaves our headquarters, aesthetics are pretty important. Thus, hiding the electronic wiring and reducing wire clutter was a priority, while maintaining practicality. Plus, we wanted to hide the bulky battery!
The removable battery door was placed in the down tube closer to the bottom bracket junction. Given all the stresses and forces that the bottom bracket must withstand, the down tube is completely reinforced past the water bottle cage screws. We used a rigid AB expanding polyurethane foam (think material inside a surf board – super light, very stiff and strong). Inside the battery door, we created a female carbon mold for the battery to pop into to prevent any rattling. The battery pack is essentially in Fort Knox.
In regards to the electrical wiring, we internally routed tubes inside the frame to protect and guide the wires.
The bike still only weighs in at 16lbs 2oz (as pictured with Ultegra road tubeless wheels). Switch to some lighter wheels and this is a light Ultegra Di2 bicycle!
Done drooling? Well, you’ll have to keep drooling because this bike has been sold. But, we can build one for you.