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Monday, 17 October 2011

Specialized Shiv DI2

Last week I picked up my 2011 Specialized Shiv.  My old bike had Shimano DI2 Electronic Groupset that I wanted to install on the new bike.

The Shiv uses plastic tubes inside the frame for all cable routing.  Additionally the bottom bracket area is a sealed tube making access to the area impossible.  When I removed the forks/stem though I could see I had access to inside the frame and the cable guide tubing

First step was to run a battery wire from the seat tube to the head stem tubing.  This involved passing a gear cable through the frame to then pull the wire through.  The cable had to go to the bottom bracket area and then up the main tube as there was no access to the top tube area.  A connector was soldered and heat shrunk to the end of the wire to allow the battery/seat post to be removed.

The battery is from a radio control model car.  It is the same voltage as the standard Shimano battery but a higher amperage meaning more time between recharges.  A corresponding connector was soldered and heat shrunk to the battery leads.  The other connector is to connect to a charger

The only modification to the frame was to cut holes in the cable guide tubing to allow the cables to exit into the head stem area. (they can still be used for manual cables as the tubing wasn't cut completely through)  The cables to the front and rear derailleurs use four wires so black alarm 4 core cable was used.  This fit snuggly into the tubing.  The main control wire from the DI2 wiring kit was passed through the top cable entry point and pulled through the same hole so that all cables could be accessed via the head stem tube.

Another view of access to the cables.

At the cable exit points the wires were stripped and soldered onto the standard DI2 connectors.  The soldered joints were heat shrunk.

Once connected the joins were pushed back inside the frame for a neat appearance.  No joins were visible outside of the bike.

The standard wiring junction box was quite large.  The small square on the right is the circuit board to replace it.

Thanks to the patent database I found the circuit design from Shimano which specified the wiring in the connector that I needed to replicate

Using a 5x4 grid all of the wires were soldered into the board.  Each row was one connection/wire, each column was a colour

All wires were securely cable tied together and, after testing, the connector was wrapped in heat shrink tubing and then wedged into the main tube.

Stage II - wiring of the aerobars to come.....